MadModder
Gallery, Projects and General => Project Logs => Topic started by: kvom on April 28, 2009, 08:10:32 PM
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I have abandoned the CO2 engine, as I have come to believe that the laws of physics will prevent me from getting it running. Some things don't scale up well. :scratch:
I think I will have a go at the Paddleduck plan Bogs posted on HMEM. I'l let this thread be a placeholder until I actually make some parts.
My current idea is to scale it up by 1.5 times and use Imperial threads and fasteners (I have a lot of 5-40 and 6-32 screws and nuts). I will also use non-metric drill rod in places where that's called for. Otherwise I will just multiply the dimensions by 1.5 and convert to inches. I have a DRO on both the mill and the lathe, so odd numbered lengths shouldn't be a problem.
I will also go somewhat for the "bling" look. I probably won't try the separated cylinders as I don't yet have a good rotary table, and as I will be running it on air and not steam I think I can skip the displacement oiler. I'm pretty sure I have enough scraps lying around for most of the pieces (I plan to do the block in steel rather than cast).
I've skimmed through the "book" once, but now I'm going to read it more carefully before starting out. The printer is going as I type.
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Why go up? Scale it down 1:3...that'll be fun! :thumbup:
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K,
John S did a double sized V twin, the same as yours. He had a little trouble getting it to run. A change to running on high pressure actually got it turning over OK. The lift pin lengths are super critical.
Shred over on HMEM is building one of my engines at this moment, and he is doing the Imperial conversion as well, but he isn't finding it too difficult, except metric has a better range in the smaller sizes of screws, so he is basically sticking to two Imperial ones.
Darren on here is getting along fine as well, but he is doing the metric version using purely marking out and manual handle settings on the machines. So you having DRO's is a distinct advantage.
If you are enlarging it, you should find no problems, as the engine has lots of adjustments in critical areas, and on the valve gear itself, you make the spools to the correct spacings by measuring between your drilled holes.
Good luck with your project, and if you have any troubles, you have the correct person reading your postings about it, and will help if it is needed.
Because you are running on air, you can make it out of almost anything you have in your scrap box. As long as it will take the pressures involved, use it.
Bogstandard
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John S did a double sized V twin, the same as yours.
Unfortunately mine is 3x, as I was seduced by a cube of aluminum that was "just the right size" for the crankcase. :bang:
My other build was Elmer's bream engine in double size, with the plans that Brian Rupinow provided. I followed his dimensions but varied the style quite a bit. It ran fairly quickly after I finished the assembly. Your engine has more parts, but I don't see any that are significantly more complex. I'm used to making the harder ones over and over anyway. ::)
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Kvom,
There is only really one difficult part to make, and that is the crosshead, but if time is taken to think about it as it is being made, even that becomes a simple job. The normally difficult bits, like the crankshaft, uses the method of, a few simple things, that when brought together, make one complicated part.
With your experience, I don't see you having any problems at all.
When finished, it is a lovely runner, even more so if it was to be made larger.
Bogs
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Hi Kvom
Look forward to seeing your build, I'm planning on building one of those engines later in the year as a break for my loco build, (when I start on it again)
Have fun
Stew
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I might try to make the crossheads first to get the harder parts done first. The other parts that are new to me are the eccentrics and silver soldering. I made the eccentric on the beam engine in two pieces, but I should bite the bullet and get the 4-jaw chuck on the lathe. Not rocket science, but tedious to adjust.
A question to make sure I understand the workings:
The writeup on the crank webs states that the dimensions are critical. I believe that this is because the distance between the two holes determines the total displacement of the piston in the block and hence must match the location of the steam inlet/outlet holes. Is this correct? Assuming this, are the diameters of the two rods that comprise the crankshaft also critical? Or in other words, can the shaft and the journals use the same diameter rod?
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The diameters should make no difference to the throw as this is measured center to center of the rods.....within reason you should be able to make them whatever you like.
Just bear in mind, bigger dia, bigger surface area, friction/load bearing surface area the two main criteria to be concerned with here.
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Thanks for the quick reply Darren. I was just reading through your thread, and hadn't realized you were now building to John's plans as well. Looking good!
I now realize I will need a slitting saw and arbor for the mill to make the crank webs. Luckily Enco has a free shipping deal going on.
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In that case this may be of interest :thumbup:
http://madmodder.net/index.php?topic=646.0
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Kvom,
If you read the writeup on making the eccentrics, you don't need to use the four jaw, but your mill.
With regards to being critical with the dimensions on the crankwebs. That is because if you don't get the hole centres the same as each other, either the crank won't turn or will wobble all over the place.
If you follow the writeups in the book, it shows exactly how to obtain the correct results, no guessing, no magical solutions, just the correct way to get what is required. Plus with you having DRO's, you should be able to do it with your eyes closed.
Bogs
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My question was the "engineering" that went into the design. Since you made the block first, did the dimensions for the webs come from the inlet/outlet spacing? My assumption is that the offset of the eccentric is likewise tied to hole spacing in the steam chest. The entire subject of valving in steam/air engines is fascinating. When building the Elmer engine, I just went along blindly following the plans, drilling holes wherever indicated, happy as a clam. It wasn't until I actually looked at the cross-section of the valve and cylinder bore in Elmer's original plan that I had any inkling how it was supposed to work.
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I don't have an inkling how this all works either, I'm hoping my build will show me the way it all fits :ddb:
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Now I understand where you are coming from Kvom.
In fact, when I designed this engine, I had never worked on a piston valve one before, and I asked around for any formulae, and Sandy (in the book) made some suggestions about timing and porting. From that information I worked everything out myself.
The relationship is the total eccentric lift (6mm), the spool lengths (3mm) (the length of the thick bits on the spindle that goes up and down in the valve block) and the diameter of the holes (3mm) that the thick bits open and close.
When I get a bit more time in the next couple of days, I will knock up a sketch how it all works in unison.
Bogs
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OK, I have one part made to justify this thread. I decided to tackle the eccentrics, as the technique in the book is interesting. I also had some suitable sized steel cutoffs.
In interpreting the plans I calculated that 1.5mm = .059", so any dimension needed is quickly calculated needing to remember only one number. So the diameter of the eccentric is 18mm -> 1.06".
The initial turning to length and cutting the end flange and groove were not too difficult. I recently acquired a very veteran B&S height gauge and a cheap ENCO granite surface plate, so that I was able to measure the lengths and face to the desired dimension fairly easily, if slowly.
I don't have a rotary table, but I used the following setup clamp the disc in the mill vise and to find the center quite rapidly:
(http://www.pbase.com/kvom/image/111927048/medium.jpg)
The indicated 5mm hole defines the diameter of the crankshaft, and so would fall between 1/4 and 5/16 inches. I happened to have some 1/4" drill rod, so that's the size it will be. That said, I can always enlarge the hole should a thicker crankshaft be needed.
Then my trouble of the day started, as my run-of-the-mill automotive class die was incapable of cutting a 1/4-20 thread in the end of the hardened rod. So I had to resort to trying to thread the rod using the lathe. Once the threading tool cuts through the hard layer the interior of the rod is a rather gummy steel that resists cutting cleanly. So after any number of tries I finally got some partial threads cut and was able to finish them with the die. Then it was a matter of bolting the eccentric piece against the face of the 5C collet/block as shown here:
(http://www.pbase.com/kvom/image/111927037/large.jpg)
The reason for this setup is that the 6-jaw vise won't tighten on a 1/4" rod, so this is my "collet chuck" setup for small rods. The chuck is very accurate, so that the runout with this setup is quite low. It's necessary to really tighten the collet when taking the interrupted cut or else the rod will just turn in the collet jaw. My turning technique was to touch the lathe tool to the innermost point of the boss and set the DRO y-axis to zero. Then when turning I could watch the DRO count down and would know when to stop the cross feed, which was running at the lathe's slowest speed of .0006/revolution.
So after 4 hours work I have 1 part to show:
(http://www.pbase.com/kvom/image/111927039/large.jpg)
I used a lock washer under the bolt, which scratched the surface a bit. For the next one a flat washer might be better.
And of course as soon as I was finished I remembered that I had a piece of 1/4-20 threaded rod that I could have used instead of threading the drill rod.
At least I'm "underwauy" :proj:
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Very nicely done Kvom, I had forgotten I had used the RT, but you soon cured it by finding the centre in the vice.
Doing it this way saves all the hassle of setting up in the 4 jaw.
Bogs
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Well done that Man :clap: :clap:
That six jaw chuck looks an andy beast :thumbup:
Stew
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Today I fabricated the other eccentric using the threaded rod. It went much faster, about an hour start to finish.
I then went through the book noting the dimensions, calculating the 1.5x dimensions and writing them on the pages, and comparing these to the brass material I have on hand. It seems I either have pieces that are too small, much too big, or else I need to make a part to fit another part that gets made first.
However I do have a number of pieces of 1/4" thick brass sheet that was originally 3" wide. Since I now had the eccentrics made it seemed logical to make the straps next. I found two pieces that were reasonably close to the top and bottom sections, squared the sides on the mill, measured each with the height gauge to calculate how much needed to be milled off, and then milled both to the calculated size.
The only point of interest to a reader might be this "technique" for clamping a part in the mill that is thinner than your parallels:
(http://www.pbase.com/kvom/image/111965691/large.jpg)
These hardened precise cylinders are also useful in ensuring proper clamping when the surface against the moveable jaw is not flat.
Once both pieces were sized and precisely squared, I drilled the holes for the screws. I am using 6-32 screws. Once the top piece was drilled and tapped, and the mounting surfaces deburred, I screwed the two tightly together and camped in the vise in order to bore the hole.
The diameter of the groove in the eccentrics is ~.830, so I wasn't going to be able to find a "lucky fit" drill bit as Bogs did. So after edge finding to locate the center of the bore, I center drilled and drilled through with the 1/2" drill bit. Then I remembered that I have a .75" end mill, and used this to enlarge the hole further. Then I had to resort to the boring head to reach the final dimension. I recently acquired a set of bore gauges, and these were immensely useful in measuring the bore with the piece still in the vise. I used Bogs' tolerance of .05mm, which is ~.002.
Next I used a 1/2" endmill to reduce the thickness of the strap (still screwed together) to fit the width of the groove in the eccentric, taking equal amounts on both sides. This also cleaned up the surface on the sides.
When assembled onto the eccentric it turned, albeit stiffly. Some lapping and run-in should take care of the fit (I hope).
Then I reclamped the top portion in the vise to drill the holes for the coupling. It seems that 3/16" rod would be a bit too big, so I drilled it 5/32. Then drilling the oil hole completed the day's shop activity. Here's the result of about 5 hour's work:
(http://www.pbase.com/kvom/image/111965694/large.jpg)
(http://www.pbase.com/kvom/image/111965697/large.jpg)
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On your way sir!
I want to do this one... hell, my list keeps getting longer and longer!
Eric
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I went through the book and made a list of all the parts, compiling them into a spreadsheet. Here's the results. Useful as a checklist:
Parts List for Bogstandard Paddleduck Engine
Part Qty Dimensions "Page #"
"Main Block" 1 54x32x18 3
Top Cap 2 18x2.5+ 11
Packing Gland 2 18x8 11
Packing Gland Adjusting screw 2 8x8 11
Piston 2 10x5 12
Crosshead 2 27x22x16 12
Piston Rod 2 3x10 12
Top Plate 1 64x50 16
Crosshead Guide Bars 2 4x39 18
Bearing Block 4 20x15x10 19
Baseplate 1 110x50 22
Crankwebs 4 28x5 24
Flywheel 1 32x10 24
Eccentric 2 18x10 30
Support Columns 4 6x10.5 32
Support Pin (if needed) 6 4x12 32
Connecting Rod 2 35x6.5x6.5 32
Steam Chest 2 40x18x16 35
Steam Chest Blanking Plate 2 32x18x2 42
Spool Valve 2 6x45 48
Eccentric Strap Bottom 2 21x10 53
Eccentric Strap Top 2 21x15 53
Eccentric Coupling Block 2 10x6x4 53
Eccentric Coupling Fork 2 6x4x4 53
Piston Valve Packing Gland 2 12x9 55
Piston Valve Screw 2 8x8 55
Steam Flange 4 12x6 57
Steam Flange Base 4 12x4 58
Steam Control Block 1 25x25x10 65
Steam Control Spool 1 10x23 70
Steam Control Bottom Plate 1 22x7 70
Steam Control Top Plate 1 22x10 70
Steam Control Arm 1 26x7x5 70
Lubricator Body 1 15x30 73
Lubricator Top 1 15x14 73
Lubricator Screw Cap 1 8x8+ 73
74 parts in all. I didn't include rods, tubing, or fasteners that don't require fabrication other than cutting to length.
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I've done 11 of them :)
Only 63 to go, see nearly finished :lol: :lol: :lol:
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Just to make a bit of a suggestion.
You don't need to go too tight on your tolerances. If you can do it, then great, but it is not absolutely necessary. The engine was designed with a beginner in mind that wouldn't be able to hold fine measurements and fits, so adjustments are in there to help with, and cure any problems. Plus as they gain more experience and confidence during the build, they will start to get better at making tighter tolerances.
I am not talking about being sloppy, but if the bits fit together without too much rattle, then it will run.
The critical bits are the spools in the steam chest, the piston to bore and the spool in the control valve.
Bogs
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I have just started learning to bore on the mill, so trying to "hit the number" was a challenge that I didn't need here, as you say. For the next one I'll likely save some effort and go for a looser fit.
I had some distractions today, mainly fixing up a new bicycle for one daughter. With the shop time I had this afternoon, and knowing the number of parts to be made on the mill, I decided to cobble together a vise-stop.
At school I made a clamp-type stop that clamps to the fixed jaw of a Kurt vise. However the jaws on a Bridgeport vise are slanted, so I can't use it. I do plan to replace this vise with a Kurt, as a friend just bought a BP with no vise and has agreed to buy mine. In the meantime, I made this one out of a few pieces of steel I had lying about:
(http://www.pbase.com/kvom/image/111998736/large.jpg)
Should be OK for the shortterm.
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kvom,
I'll bet you'll keep that one around fro sometime to come. :)
Did you tap all the way through that block or do you have a nut on either side?
Bernd
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Did you tap all the way through that block or do you have a nut on either side?
The round shaft is 5/8" diameter. I used a 5/8" end mill to cut a pocket 2/3 of the way through the plate. On the bottom is a hole for a 1/4-20 flat-head screw that is countersunk. I drilled and tapped the bottom of the shaft to accept the screw.
There is a jam nut on the other side of the threaded rod; that hole isn't tapped.
I used the stop after dinner to make the other eccentric strap. It definitely saved time, as I was able to finish it in about 2.5 hours. I also used the abs/incr feature of the DRO for the first time. I set the abs (0,0) coordinate to the stop and the fixed jaw, but then I was also able to switch to incr mode without losing that abs coordinate. Once I had the abs dialed in, I needed to use the edge finder only once more, so find the center for boring (I could have calculated it, but wanted it to be exactly on the seam).
This time I bored it .004 over the eccentric groove and it turns very freely. I still need to drill the two holes though, and also drill and tap the holes for the setscrews on the eccentrics.
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I did a few calculations around the crank webs and the connecting rod. I have access to a goodly amount of .25" thick brass plate, so I'm planning to cut the webs from that, although proportionally it's undersized. Given the spacing between the pillow blocks, the crank end of the connecting rod would need to be increased somewhat, to ~.45". Since I just ordered a stick of .5" square brass rod, that seems the way to go.
So this morning I cut out a roughly 1.8" square of the plate with a hacksaw, drilled a 1/4" hole in the center, and turned it down on the lathe using the same clamping method as for the eccentric. It took a few tries to figure out the best clamping method, but eventually I arrived. It would be quicker all around just to mill out the discs with a rotab, however.
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Kvom,
I couldn't understand the way you are going to take up the missing space, so either make the crank blocks longer (expensive), or put a spacer in between the crank webs and blocks to take up the side slack.
John
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On the plan, webs are 5mm and conrod is 6.5, so 16.5mm. Scaling up this gives .974" of material. If my webs are .25" each, then the conrod end would be .474" to give the same spacing. This is opposed to the .384" it would normally be. Since I'm starting with a .5" square bar, I won't need to add a spacer.
***edit***
I made the second disc using the Palmgren (copy)? rotab, cutting it out using a 1/8" 4-flute endmill, the smallest I own. No real problems, other than the usual hassle of clamping small pieces with big clamps and bolts.
I'm now out of pieces large enough, so will need to resupply on Monday night. I think I know a better way to do the other two.
I'm wondering if the 1/8 endmill is too wide for slitting the webs? Opinions?
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Try a 1/16" slitting saw if you've got one, it would look more in scale.
Stew
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I spent a couple of hours in the shop after dinner starting on the packing gland.
For the screws, I decided to use a diameter of 15/32 so that later, when I need to turn the flange to fit the cylinders and drill for the piston rods, I will be able to hold the glamd in a collet rather than the chuck. The thread is 3/8-16. I had no real issues turning the screws as I had a piece of 1/2" brass rod to start with.
I then turned the gland itself, with the inner diameter 15/32 to match the screw, and the outer diameter 1", turned from a piece of 1" brass rod (took .001 off for finish). Then drilled and tapped to match the screw. After parting there is enough extra length left to turn the inner boss for the cylinder bore.
My only "problem" is that the screw won't go in all the way, because the tap won't cut enough threads (pointed part is too long). If I can find a bottoming tap at school I'll fix it that way; otherwise I can always shorted the screw portion.
Thoughts?
I finished only one gland, so the other is on the agenda for next time.
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I ground the tip off the tap and was able to get the threads deeper into the gland.
Unfortunately I discovered that one of the screws goes in slightly crooked, so I'm pretty sure that means a redo on that one. And then I screwed up the straight one milling the side flats, so that's a redo as well. :hammer: I think it's going to be preferable to mill the flats before parting off the screw, as then I can mount the rod in a 5c collet in the square collet block for milling.
I did find one more piece of brass big enough for a crank web, so now I have three - one to go.
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A little progress this afternoon:
Reading through the book I noticed that the valve packing gland is almost identical to the piston gland (flange is a bit smaller). So since the 1" round stock was still chucked in the lathe, I turned two of these. I left the flange diameters to be turned down when the boss for the bore is turned.
I found out that my class is cancelled for tonight, so I won't be able to get any more brass material until Thursday, unless UPS arrives with the 1/2" bar I ordered.
I decided I could make the plain pipe flange from the 1" round stock. I chucked the bar in the billing vise using v-blocks and cut the flats wide wide enough for two flanges. Then I chucked the bar in the lathe and drilled it assuming 1/4" pipe.
(http://www.pbase.com/kvom/image/112135197/large.jpg)
Then it was just a matter of turning it down to the correct diameter and parting off.
(http://www.pbase.com/kvom/image/112135199/large.jpg)
Looking at the photo it seems they're slighly unbalanced, but I can correct that when it's time to drill the mounting holes.
Given the larger size, I'm wondering if brass will be strong enough to make the long flanges. I may try to make a couple.
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Spent the evening making 4 identical packing gland screws. Mounted a 1/2" brass rod securely in the square collet block in the milling vise. This allowed me to mill flats on opposite sides for all 4 screws. The flats fit a 3/8" wrench.
(http://www.pbase.com/kvom/image/112150688/large.jpg)
Then I chucked the bar in the lathe and turned the OD to 15/32. Then for each screw:
- turn the end section to be threaded to .370" for 3/8-16 threads
- undercut the end of the threaded section at the head
- single point the threaded section on the lathe to a thread depth of .06"
- finish the thread form with a die
- test fit to a gland for good measure
- part off
Took about 1:15 for the 4 pieces
(http://www.pbase.com/kvom/image/112150694/large.jpg)
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After lookomng at the drawings and measurements once more, it looks as if the 1.5x goal has put me into the "expensive materials" category, as the block will be just over 3" long and 2" high. Trying to find brass with those dimensions doesn't appear straightforward.
I am thinking it should be possible to make two separate cylinder blocks. Any reason that won't work?
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Kvom,
I'm building the same engine in approximate 1-1 scale with colonial imperial threads.
Perhaps cast iron for the block would be possible using 1 inch thick bar stock which is a little thin
http://www.mcmaster.com/#cast-ductile-iron/=1qzvag
or use brass or bronze liners in an aluminum block.
Dave
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Kvom,
Are you going for steam or air driven?
I keep asking this question, but it does mean that if you are only going to run on air, then almost anything will do for the main cylinders, even something like nylon could be used if you can get nice smooth bores. I would suggest a nice cheap material like free cutting mild steel. EN1a here in the UK, or ali.
But if going for steam, then cast iron, bronze or brass should be your first choices.
I have included a C-o-C for perusal.
The central mounting bolts do play an important part in the makeup of the engine, in that they stabilise the central portion of the top mounting plate.
But if you can get the hole pattern in like is shown in the bottom sketch, that will do almost the same job, and I wouldn't envisage any flexing problems.
If running on steam, in fact, having a gap between the cylinders will help in the steaming qualities of the engine. It will allow the engine to warm up a lot quicker and produce less condensate. Have a look at how I have seperated the cylinders on the 'blinged' one. That reduces the mass for the steam to warm up, but still retains the one block principle.
Before doing all your final 'exact' calculations for the cylinder bores, settle on a size that matches generally available o-rings. The engine will run quite happily without rings on either steam or air if a couple or three fine oil grooves are put around the piston, but again, if you want to fit rings, if just air, anything will do, but again, with steam, the choice is limited to either Viton (recommended) or silicon (not recommended if WD40 or most other spirits are coming into contact with the engine for cleaning).
I hope this helps you in some way.
Bogs
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John I am building this too. but am have truoble getting a good finish on the bore. I am using imperial and made my cyl 3/8, how big can I ream them and not effect performance?
Ron
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I will be running strictly on air, and using an oiler-regulator for lube rather than the displacement oiler. For that reason I also plan to make the handle on the control block more like a manual one. I plan to make the pistons from aluminum with oil grooves rather than rings.
I am really wanting to have an "all brass" engine for the look. I could definitely change the mounting hole pattern for more stability. I do have a block of a reddish brass alloy at school that might work, but will have to wait until tomorrow night to get a measurement. It's the same material from which I made the cylinder for my beam engine; someone thought it might be beryllium-copper.
In the meantime I got my 1/2" brass bar yesterday and now have plenty to do making the connecting rods and couplings. Especially since we are having a nice thuderstorm at the moment, so outdoor activites are off for the day.
Thanks for all the ideas.
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I will be running strictly on air, and using an oiler-regulator for lube rather than the displacement oiler.
Just out of interest whats an oiler-regulator :scratch: its a term I've not come across before.
Thanks
Stew
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Stew,
Trying to figure out how to tell this. It's sort of a small container that is added on after the one that removes water from an air compressor. The unit allows you to adjust the drops of oil into an air line to lubricate air powered tools. I'm sure you've seen them before, it's just our two languages again causing the problem. :)
regards,
Bernd
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Thanks Bernd
That sorted me out :thumbup:
Stew
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Ron,
You can go as large as you need to, but keep an eye on the flange mounting screws at the end of each bore, don't go too close to the screw holes as they might weaken and strip out if you get too close. Just make the spigots on the flanges to fit the larger bores and of course, the pistons.
Kvom,
Be very careful machining it if it is beryllium copper, it releases some nasty things when machined under certain circumstances. I would have a look on the web for info on how to treat it while machining. It is always better to be on the safe side.
John
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I don't have much to show for 4+ hours of work.
(http://www.pbase.com/kvom/image/112225787/large.jpg)
My first goal was to mill the brass to size for the conrods, but I was having all sort of problems with the finish. After changing endmills a few times without success, I noticed a little light on the control panel of the VFD : rev. I had been running the spindle in reverse. :hammer: This is not something that would be likely to happen using the normal mill switch. Either I left it in reverse after boring the eccentric straps in back gear, or I fat-fingered the button (which is right above the run button. As I was running the mill at 2000 RPM I didn't really notice that it was turning back-asswards.
So after wating a fair amount of time I did manage to mill the brass to size, center drill the ends, and drill/ream the holes at 1/4". My intention is to turn the conrod like John's, between centers. Since I need to borrow a lathe dog from school to do this I'm leaving the rest of the milling for afterwards.
I then decided to make the crosshead guide bars from some 1/4" drill rod. After some calculations on dimensions I settled on drilling and tapping the ends for 6-32 screws. Rather than mess around with the collet blocks to hold the rod, I switched to the rubberflex collet chuck. Drilling the rods was not much of a problem. However, when I attempted to tap the first one still chucked, I broke my automotive-quality tap off in the hole. I was able to extract the tap, and decided to tap the rods later using the mill as a tapping station. This rod didn't take will to parting either, as once the parting bit is halfway through the rod snaps off, and also causes the chucked end to bend at the chuck jaws. So after the first one, I just used the DRO to mark the length, parted just enough to show where to cut, and cut it off with a hacksaw.
Now that I had the 4 drilled pieces, I proceeded to tap them at the mill. The first two went fine, but on the third I snapped off my only remaining, good quality, 6-32 tap. So that was then end of that for now. :bang:
I decided it was time to take a break.
Perhaps I need to anneal these rods before tapping!?
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Thank you for posting that, I was feeling quite left out.......... :ddb:
Amaizing how it still mills backwards.... :doh: But you look like you are winning :clap:
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This morning I attempted to machine an eccentric coupling fork. Unfortunately when I started to mill the slot I discovered that a 1/4" slot is too wide. It scales to .236. And in addition my 1/4" end mill is slightly oversize as well. So on to a redo with the 1/8" endmill. On the bright side I came to undestand that it's quicker to square off the stock for both forks at the same time and then cut them apart. :smart:
I had an excellent trip to school this afternoon to discuss my engine issues with the instructor, and to borrow some needed gear. So to total it all up:
- He recommended that for tapping the drill rod for the crosshead guides, I should drill the hole with 1 or 2 sizes up on the drill bit and somewhat deeper. That will lessen the chance that I will break the tap (and I got a new tap to try it with).
- borrowed a 1/16" slitting saw on an R8 arbor for slitting the crankwebs. Here he suggested that clamping all 4 of the discs together and slitting them at one time might make for a more rigid setup. By leaving the pins in the holes used for milling level, the setup can be the same, and the pins removed as the saw blade nears the hole. He suggested slow RPM and slow feed.
- Borrowed 2 lathe dogs for turning the conrods between centers (looks as if either will work). I also got a piece of steel from which I plan to make an adjustable dog that fits my chuck.
- scored a piece of brass plate 1/4" x 3" x 8" that will serve to make the bottom plate, the 4th crankweb, and some of the other smaller plates as well.
- Found that the block of mystery brass alloy in my lockers is large enough for the block, and possibly even two of them. Another piece of the same allow can make all 4 bearing blocks.
- The 2" round silver brass that Cedge gave me will get a slice cut off for the flywheel.
So it looks as if I am set for material except for the top plate. But there is a fellow on eBay who sells pieces that will be suitable.
Nothing stopping me at the moment but lack of energy. :whip:
Here's the result of the evening's efforts. Two forks for the eccwentric coupling. Haven't drilled the holes for the pins as yet.
(http://www.pbase.com/kvom/image/112271362/large.jpg)
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I can't seem to find a description of the threaded adjuster that connects the eccentric fork to the spool valve. Can you point me to the right spot in the book? Or is iit just a length of threaded rod with a jam nut?
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Kvom,
Here is the description, not much, so that might be why you couldn't find it.
Yes it is just a bit of threaded rod and a locknut.
Bogs
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I did some measurements and discovered that I indeed have enough brass for both the top and bottom plates, so as of now the only material I am missing, AFAIK, is the correct diameter drill rod for the spool valves.
My first task this morning was to cut the ~6"x3" bottom plate blank out of a 9x4 piece of 1/4" brass. I could have done this on the bandsaw, but decided to mill it out with a 1/8" endmill. It took longer, but in the end I wasted less material. From the cutoff, I then cut out a piece big enough to turn the disc for the 4th crankweb. My boo-boo was to crank it a little too hard and broke the endmill. Luckily it's a double ended mill, so I still have one to go.
I was going to post in detail about another fubar I did, but I'll just summarize it by stating that when tapping a hole, look to see that you do indeed have the correct size tap in the tap wrench. :hammer:
After lunch I tackled the crankwebs, now that I had all 4 discs cut out. Drilled the holes and pressed in the drill rod. I am using 1/4" for both shaft and pin:
(http://www.pbase.com/kvom/image/112295101/medium.jpg)
My little arbor press was handy here. Milled the first side:
(http://www.pbase.com/kvom/image/112295102/medium.jpg)
I used a 3/8" ball-end mill to get the rounded inner corner. Then the other side:
(http://www.pbase.com/kvom/image/112295103/medium.jpg)
All ready to be slit:
(http://www.pbase.com/kvom/image/112295104/medium.jpg)
I'm not sure whether to drill and tap the lock screw before slitting.
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Kvom,
Wait until after slitting, then just drill all the way thru with your tapping drill, then using your clearance drill, go down until it reaches the slot. Then cut the thread. It save lots of trouble finding the correct depths to drill to.
Bogs
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Yesterday evening I had squared up the base plate and flycut the top surface. As it was still in the vise this evening I continued to drill the holes in the plate. After center drilling all of them, I came to the conclusion that the scaled metric screw for the bearing blocks was between a 6-32 and an 8-32 SAE. Since these are not visible, I decided to go with the larger screw. I used a #20 drill bit for the 8 inner holes, leaving ~.003" clearance. Since my parallels were under the points for the perimeter holes I decided to defer drilling these. I'm not sure how I will be mounting the finished engine.
I then proceeded to slit yesterdays crank webs using the borrowed slitting saw/arbor. This went nicely and quick fast. I used the same drill rods in the holes to clamp the webs parallel to the top of the vise jaws. The mill was running in back gear at 200 rpm with a feed rate < 1ft/min. The exposed radius of the saw was "just" enough to reach the small end hole.
Having been out and about in the sun all day I decided I was sufficiently tired to call it an evening, before I did something silly.
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As Sunday was Mother's Day here, most of the day was spent on family doings. Plus I was starting a minor repair to reweld the fenders on my car hauler trailer. However, at the end of the day I decided to cut off the metal for the block using the big horizontal bandsaw from the 1940s that I recently restored.
The metal was a chunk of 1x2x7" bar of coppery alloy. When cut the surface looks like a new shiny penny, but the patina is a dark brown chocolate color. My goal was to cut a 3.25" piece. This was the first time I tried to use the saw on anything other than a test on some 1/2" brass bar (which took 2 seconds to cut through).
The first and second attempts to start the cut saw the blade pop off of the drive wheels. I finally got the tension tight enough and was able to start the cut, but had the feed adjusted too slow. I left it to run while sweeping up a weeks' worth of swarf, but after 20 minutes it was only halfway through. I let off on the hydraulic cylinder a touch and it sawed through the next inch or so in a couple of seconds, then slowed. Another touch off and it cut through. In conclusion, these old saws need a lot of manual adjusting to cut, but once it's right they can really rip through the material. The resulting cut was quite straight as well.
I need to do some measuring, but I am hoping to get the steam chests and bearing blocks from whats left over.
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I spent a few hours today starting on the engine block. It took some time to square it all up as the material doesn't like big cuts or fast feeds. Too fast and it throws off dark chips and smoke. In addition it creates a lot of tough burrs, so lots of filing to debur the edges after milling each side was necessary.
The dimensions ended up right on for thickness, and about .100" large on height and width. Based on the material I have, the steam chests may be somewhat thinner than spec, so I am planning not to adjust the block width until I can measure them.
In any case, the cylinder bores are positioned relative to the center lines, so I proceeded to drill these. I am going to leave the bore at .500, which although somewhat less than scaled, is the size of my largest reamer. Were I to bore it to .590, the displacement would be 3.375 times greater than the original. As it is, the displacement will be 1.907 times.
(http://www.pbase.com/kvom/image/112413046/medium.jpg)
I was concerned that scaling up the steam holes from 1.6 mm might not work, as I would presumably want the area of the opening to be approx. twice as large. Since a hole with twice the area is .089" in diameter and a hole 1.5 times 1.6mm is .094", it seems irrelevant.
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After milling the main block, I was determined to make the rest of that bar serve for the steam chests and bearing blocks, as I have no other thick brass.
The piece destined for the steam chests was just wide enough for two, but I was afraid that if cut on the bandsaw one piece would be too small. So I used the slitting saw to slide it in two on the mill. I can say that the level of "chatter" was more like a scream, but feeding at less than 1 ft/min at 300 rpm finally got the job done. After squaring the two resulting bars, I found that the height would be less than scale, but still enough for the computed valve bore with a decent amount to spare. I then milled one side to the proper width, but left the depths unchanged. Given that the datum lines are center lines, I can drill all the holes and clean up the depths at the end (I might possibly need to reduce the depth of the block slightly as well).
The remainder of the material was 1x1", meaning that the depth of the bearing blocks will be slightly smaller than scale. Before I mill the width I need to calculate an allowance for the smaller than scale crankwebs.
So not a lot to show in finished parts, but a lot of time spent on the mill.
The scale for the valve bore is between 5/16 and 3/8, so I will need to order some drill rod. Luckily Enco is running a free shipping + 10% discount the next two days. :beer:
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Not having any bar stock large enough for milling the crossheads, I did some calculations and found that I could get a block cut from some 2" round stock. I still has a chunk of mystery brass alloy that Cedge gave me, so I cut off a 1" slice on the bandsaw and milled it into an ablong block. This was yesterday; today I decided to continue. I didn't get far. :bang: As I was drilling one of the holes for the guides, I noticed a hot spot on the side of the block. Seems this metal gets hot when drilled, and actually melted at the bottom of the hole:
(http://www.pbase.com/kvom/image/112527645/large.jpg)
Since I also had a piece of 360 brass 2" rod, I went to Plan B and repeated the milling operation. Once I had the first block, I calculated that it was 62% of the original disc:
(http://www.pbase.com/kvom/image/112527644/large.jpg)
Here's the machining sequence for anyone that's interested. First, since the sides of the disc are reasonably straight, I chuck the disc in the vise with one side flat against the fixed jaw and mill one face flat to remove saw marks. Next I reverse the disc with the flat face on parallels and mill the other face. Now I can clamp the two flat faces on the vise jaws and mill one side (after calculating how much to cut). This flat side is then clamped flat on parallels to mill the opposite face. I now have something that looks like this:
(http://www.pbase.com/kvom/image/112527646/medium.jpg)
I then use a square to clamp it vertically.
(http://www.pbase.com/kvom/image/112527647/medium.jpg)
Once I had an oblong block it was a matter of carefully drilling and milling the crosshead out of it. I didn't find the optimum milling sequence, but all was fine in the end.
(http://www.pbase.com/kvom/image/112527648/large.jpg)
Hopefully I'll finish the other one the next time in the shop.
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Rather than finish the other crosshead, I decided to work on the bearing blocks that I had roughed out last week. It was tedious work, but nothing fancy. The vise stop saves a lot of time in repetitive operations on multiple parts. I did drill the oil holes before reaming the bores so as to avoid burrs.
For turning the bosses on each side, I used the same fixture I used for the eccentrics: a piece of aluminum round drilled and tapped 1/4-20. The first one turned out poorly, with a lot of tearing. I was using a medium speed and slow machine feed on the crossfeed. This alloy needed just the opposite: lots of RPMs and fast feed. Here's the results:
(http://www.pbase.com/kvom/image/112597137/large.jpg)
I did discover a potential problem. I drilled the holes for mounting the blocks on the base plate according to the plan. However, the material I had for the blocks was smaller than spec, so the blocks ended up .18" shorter in the longest dimension. Fortunately the blocks cover the holes, but using the planned 8-32 screws to attach them will mean that the tapped holes in the base of the block will be extremely close to the edges. I think I will just use 5-40 screws, leaving more "meat" around the holes. However, I'm going to sleep on it before making any decision. I could conceivably drill a second set of holes in the plate inside the ones I already drilled. In any case, I have not drilled mounting holes in the base of the blocks.
Any other ideas are welcome.
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You don't need to use large mountings, anything just to hold the blocks in position so they can do their job of supporting the crankshaft. Even tiny screws would have enough strength to hold them in position.
It will be the same for any fixings that hold pieces together, they don't have to be large just for the sake of being at the same scale. Use what you have.
Bogs
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Thanks, John.
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It's getting there. This is a nice build to watch!
Eric
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My first goal of the afternoon was to finish milling the second crosshead. I did it in a different sequence, and although it required an extra reclamp in the vise, I was able to clamp solidly against the jaws more often. The first operation was to expose the conrod bracket (three cuts in one vise position):
(http://www.pbase.com/kvom/image/112651546/medium.jpg)
Then two cuts on the "cheeks":
(http://www.pbase.com/kvom/image/112651548/medium.jpg)
Afterwards it was just the cross cut on the Y-axis and milling the slot.
(http://www.pbase.com/kvom/image/112651551/medium.jpg)
After patting myself on the back and enjoying a soft drink, I drilled and tapped the bearing blocks.
(http://www.pbase.com/kvom/image/112651553/medium.jpg)
There was just enough room for the 5-40 screws. Right now the bores are a tight fit on some 1/4" drill rod that I lapped with some fine sandpaper. I need to do the same thing with a longer piece to lap out the bores and align the blocks precisely on the plate, as shown in John's writeup. I'd like to get the base cutouts done next so that I can trial fit the eccentrics and cranks.
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Kvom,
The crossheads are the most difficult part to machine because of all the operation and position changes that needed to be done.
Now you have got those out of the way, most other jobs should be plain sailing for you.
Very nicely done.
John
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John,
The machining was not really a big concern in starting out on this build, (knock on wood) especially with the details you provided. My big concern is the silver soldering, which will be completely new to me when I get there.
Kirk
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Kirk,
Nice work on the cross heads. You made it sound very simple.
I see Bogs is keeping an eye on you while you build. One of these days I'd like to build one of these engines too.
Bernd
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Kirk,
I go fairly deeply into silver soldering the parts on the build sheets, purely for the reason you have said, it can be a very daunting task when you have never done it before.
If you can get it mastered, it will open up a totally new area of model engineering to you, by allowing you to make joints that are stronger than the parent metals.
It is a shame I cannot send you the items I use, but I don't know how customs would react to little packets of a very fine white dust. But I will see what I can do for you.
The flux and the fine silver solder wire are the two things that would make it so easy for you.
Let me have a root in my box of tricks, and I will PM you.
John
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Kirk
You'll be ok with the silver soldering Johns instruction will put you right, newbies struggle getting the temperature right try it on a bit of scrap first, when you hit the correct temperature the solder just flows like water. Keep the bits clean and use plenty of flux.
I used a small plumbers gas blow lamp for a long time, and got good results, see my loco build post for the last month, for pics of heat source.
Good luck
Stew
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I have read the soldering techniques in John's writeup, and will certainly try it out on scrap first.
I asked about firebrick at Lowes and was told they don't carry it. I need to visit a shop that builds fireplaces to get a few. I have a "mapp gas" torch that I think will generate enough heat, as that is what we used to silver solder the joints on the linesets for my AC lines. I'll look for citric acid one of these days. There are some eBay vendors selling silver solder wire that looks appropriate: 56% silver.
In any case I still have weeks of machining to go.
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Bogs gave me a demo on silver soldering when I was over there.
He made it look so easy...but I imagine not having seen him do it then I would mess up myself at first.
What surprised me was just how much heat was put into the part to make the solder melt. You need to get it really hot.
Been following your build with keen interest, nicely shown and looking good :thumbup:
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I'll look for citric acid one of these days.
Coke Cola/Pepsi or lemon juice will do the trick you just have to leave it in a bit longer.
Stew
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Kirk,
Check out a place that carries welding supplies. They should also carry silver solder and flux. I use Harris Saftey-silv 45. It melts at 1370 degrees F. The flux is Harris Stay-silv white braxing flux.
Make sure both parts are clean of dirt and oil. Put flux on both parts. Put the two parts together. Put a small piece of silver solder on the joint and heat till a dull red. At that point you should see the solder start to turn to a fluid. Let cool before moving. When still hot to the touch put in acid bath.
I use sulfirc acid. I get that at the hardware store. They sell it as drain cleaner. This is concentrated stuff. I dilute with water. Always pour the acid into the water, never the other way around.
Bogs explained all that in his section on building the engine as you have already said.
Good luck with the soldering. I see it as nothing more than soft soldering but using more heat.
Regards,
Bernd
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Thanks for all the advice. I'm actually looking foward to trying it. I'll use the citric acid as it sounds simpler and safer.
Today I had a couple of hours in the shop before going off to school. Ny task today was the cutouts on the base plate. I started by measuring the faces of each of the bearing blocks with an edge finder. I then used my height gauge scribe to make very faint marks on the plate. These were just as checks on where the cutout corners are supposed to go. Since I was going to use a 1/4" endmill, I spot drilled each corner 1/8" in from the computed dimensions, using the scribed lines as a check. I then drilled 1/4" holes (end mill is the type with the small hole in the center, hence not useable as a dril).
Here's the result:
(http://www.pbase.com/kvom/image/112686404/medium.jpg)
Next I made all the horizontal cuts using the table feed:
(http://www.pbase.com/kvom/image/112686408/medium.jpg)
The Y-axis slots I had to do by hand.
(http://www.pbase.com/kvom/image/112686412/medium.jpg)
After deburring the edges I remounted the bearings to check my work. I looks as if I will need to slightly enlarge under one of the bearings a bit.
(http://www.pbase.com/kvom/image/112686416/medium.jpg)
I had a little time left, so I drilled and tapped the lock screws for the crank webs (did I ever mention I hate tapping?)
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Looking good kvom :thumbup:
CC
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Kirk,
PM sent to you.
John
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The welding supply place I went to did have silver solder, but what they had available was pretty thick stuff that didn't do so well for little parts. The flux they had was ok. If you've got a few days, I'd surf on over to http://store.sra-solder.com/section.php/89/1 and get some 0.031" dia BAg-1 wire or the like (they have Cd-free if you prefer). $20 will get you plenty for more than 10 of these engines and the thin diameter works well for pre-formed rings (silver soldering with pre-formed rings like John says below is highly recommended)
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If you go down about half way on this post, it shows what you should be aiming for, and how I achieved it.
http://www.homemodelenginemachinist.com/index.php?topic=1500.msg13808#msg13808
I hate wastage and extra work. Use only enough materials to complete the job. Any excess and you will be trying to clean it off to a satisfactory condition for hours. You should be able to pickle the part, a quick rub over with wire wool or scothbrite, and the soldered assembly should look presentable and ready to use. Not like most silver soldering you see, like a bird has crapped all over it, with flux and excess solder dripping all over the place. I only hand feed flux and rod in dire circumstances, all other times I do it as shown.
OK, it is a bit like a black art, but once you have mastered it, a little bell rings in your head, and from then on, you should be making perfect silver soldered joints whenever you want them.
A special little trick to use. If you can't get the bits to hold together while you solder it up, deform the end of the tubing slightly so that when pushed into the hole, it stays where it is put. With soft copper tube, that is maybe pinching between your fingers to get the effect you want. For larger bits that fit together, use centre pops on the joint areas to expand the metal so they become a slight interferance rather than a slip fit. Once it is all done, you will never see you little 'bodges' ever again.
John
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kvom,
Here's a link to a guy that has silver soldering down pat. Scroll to the bottom of the page and you'll see one or two of his drawings showing his method of silver soldering.
http://www.craftsmanshipmuseum.com/Hiraoka.htm (http://www.craftsmanshipmuseum.com/Hiraoka.htm)
Bernd
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I had a few hours today interupted by several honey-dos. Got the steam chest holes drilled. I am going to hold off on reaming the valve bore until I'm ready to fit the valves. I decided to go with a .375" bore and ordered some drill rod of that size today. In any case I drilled the bore 1/32 smaller. The steam ports are .177". The flange mounting screws will be 5-40. I didn't tap these yet (did I mention I dislike tapping?). For mounting the steam chest to the block I will use 8-32 screws, hence the mounting holes are drilled accordingly.
(http://www.pbase.com/kvom/image/112738482/large.jpg)
I also made a flywheel from the Cedge mystery alloy (silver bronze). It's hard to work with, but is very "pretty" when polished. I used the badsaw to cut off a 5/8" slice from the 2" diameter rod, but since the saw didn't cut straight the wheel ended up .55" thick rather than the scale .59". I wanted to machine a rim/hub recess, and normally would use a parting tool. However because the cross slide on my lathe has a very short travel, the parting tool in the QCTP holder won't go close enough to the center. So I needed to grind a HSS tool blank into an appropriate cutter. That took quite a while, but gave me a chance to use the new 46-grit grinding wheel for the first time. I plan to bling it up a bit, but here's the first version mounted up for a trial fit:
(http://www.pbase.com/kvom/image/112738483/large.jpg)
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Looking good.... :thumbup:
Which reminds me, I must get back to mine......just letting you show me how... :ddb:
I believe Shred who has just joined us is building one too?
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Kirk,
I have got the bits for you, and will get them away next time the wife takes me out.
It is starting to look very impressive and well made. It is a fairly large engine at normal size, but yours will be a monster.
John
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I have two questions about the slots that connect the steam ports in the steam chest and cylinder.
1) There are dire warnings about going over the "line". I know the cylinder ports are close to the top/bottom of the block, but as long as the slot doesn't exceed the bottom edge it doesn't seem there would be a "leak". Am I missing something?
2) Would it not be equivalent to mill slots in the block?
I plan to follow the plans, but am interested in the whys/wherefores from curiosity.
On another topic, I am currently taking an evening course in CNC lathe programming. I will be making an actual part on the Haas SL-1 lathe lather this week as the culmination of the coursework. Over the summer I will be continuing, taking a course that will involve more programming and making more parts. Rather than use the canned exercises, I have the opportunity to design my own class projects, and so will be making the columns during the class. I should be able to come up with simething that would be hard to do manually.
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Kirk,
You are quite right, you could cut the slots in the block. You have to visualise how I made this engine. There were no designs or plans for it, it was a matter if making the next bit to fit onto the previous piece made, only going forwards, with very little planned for going back to a previously made piece, hence the slots were put onto the part that was made at the time.
With regards to coming close to the edge. I made this engine to be an easy exercise, so no complicated gaskets to cut, with everything being sealed with a liquid gasket compound, which works much better when no very thin lands are used, so hence, don't go beyond the line as you will start to get into 'blowout' territory.
If you think that by cutting slots into the block would be better for your build, then please do it. Nothing is written in stone, and as I said, I was making it on the run, and as such some things will defy general logic.
You are quite right in querying some of the ways I did things, and proves you are thinking about what you are doing rather than doing a 'lemming' build. But as proved by myself, and other people, the engine will run if built as directed.
I think if I went back to it, and really looked at the design, I suppose I would have done a few things a little differently, but hey!, it works!, so being as lazy as I usually am, I left it as it was.
It was the same when I did the refurb on that Marcher steam engine, I found some glaring mistakes in John Bertinat's plans for it, but the engine works if built from plans, but would run a lot better if some slight modifications were done to his instructions and plans.
John
John
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John,
Thanks for confirming my thoughts. Personally I think the design is really interesting, and I believe I can see how you developed things as you went along. That said, there was obviously a great amount of looking ahead, and certainly your experience in both engines and machining went into the process, whether conscious or not.
It seems to me that the slot in the block will be better/easier/safer. You can start the slot at the height of the steam chest port and use the inlet hole on the block as the "stop point".
One other factor that makes this build enjoyable is the nice mix of milling and turning.
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Today I decided to make the upper plate, as I had limited shop time available. I started with a 4"x4" piece of .25" thick brass plate that had been flycut on one face. After squaring the sides I used a 1/8" endmill to saw the short side, then used an endmill to bring to the final dimensions.
Since all of the holes are or can be referenced from the center, drilling them was an exercise in cranking the handles and watching the DRO. I drilled all of the mounting holes to take 6-32 screws. The large holes for the glands needed to be slightly over 1" in diameter. I used a 3/4" end mill (my largest) to make the initial hole, and then the boring head enlarged them to ~1.05 (loose fit arounf the gland).
I didn't make any cutouts as I want to see how the plate looks when mounted before deciding on any blingification.
(http://www.pbase.com/kvom/image/112803110/large.jpg)
As I was taking the photo UPS arrived with my 3/8" drill rod, so machining the valves may be the next task.
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One other factor that makes this build enjoyable is the nice mix of milling and turning.
Actually Kirk, the first proviso on the build was that it could be machined completely on a lathe with a vertical slide. Having a mill would be a definite advantage, but not essential. Hence no difficult angular port drilling normally associated with an engine of this type.
On your last post, don't forget to give yourself a bit of 'wobble' clearance on the crosshead support holes. I was a little lax in getting my crosshead holes in the right positions, and needed that adjustment to get the engines to run.
John
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A full afternoon's work in the shop resulted in exactly one useable part:
(http://www.pbase.com/kvom/image/112845072/medium.jpg)
The two other valves that I started ended up in the scrap bin because of various operator errors. On the positive side I did learn the best way to turn this rod to get a better finish, and I can probably make a valve in less than half an hour if I don't mess up.
I decided that the lathe karma was lacking, and decided to move to the mill for a "simple" piece, the blanking plates. Well I messed up there somehow as the holes didn't end up centered. So I figured it was time to call it a day.
As for wiggle room, I think I need to plan for that on the steam chest/blanking plates. I drilled the holes with a #20, which is a close fit for an 8-32 screw. Using the DRO to drill the holes for the plate, I found that the screws would "just" go through the plate and the steam chest. I plan to enlarge these holes by a couple of thousands so that when attached to the block I will be able to wiggle them slightly in case the bores on the block and steam chest are not perfectly aligned.
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Kirk,
There is no shame in making wiggly holes, as long as they are not seen in the finished article.
You can sometimes strive too much for precision fits. On mundane items like mounting holes, give yourself a break.
John
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Here's the summary pic of today's progress:
(http://www.pbase.com/kvom/image/112867424/medium.jpg)
Got the other valve made, although it took longer than the hour I estimated yesterday. I also reamed the steam chest bore to .375" to match the valves. Of course now it's a press fit at best, so some lapping is due there.
The same is true for the block, where I re-reamed the bores to .5" to remove the burrs caused by drilling the steam holes. I then drilled the holes on each end for attaching the steam chests. The afternoon finished with turning the pistons, which are likewise a press fit and require lapping.
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I had a couple of "days off": Sunday my daughter had invited 15 or so of her closest friends to have a party to celebrate the end of the school year, as well as to inaugurate the playroom upstairs from the stop. Dad was "politely" asked not to run any noisy machines during that event. Monday we had a long afternoon invite with some friends. But today I had most of the afternoon to play in the shop.
The first task was to turn the top caps, after which I drilled and tapped both them and the block. I also tapped the mounting holes for the upper plate, allowing a test fit:
(http://www.pbase.com/kvom/image/113020879/medium.jpg)
I then made a pair of blanking plates and tapped the mounting holes in the block. The DRO did manage to get the holes in all three parts to line up, so I was able to screw them all together. The only "glitch" is that one of the valve holes is slightly obstructed by the plate, but taking apporx .01" off that end should solve that.
Since I had the top section chunks lashed together, I was interested to see how it would look connected to the bottom. I'm going to make the columns during the summer CNC lathe class, so I decided to quickly make a set of plain columns from some 3/4" Al round I had previously scavenged. I had only enough time to finish two of them:
(http://www.pbase.com/kvom/image/113020880/medium.jpg)
The soda can is included as a size reference.
Now it's time to get cranking on the crankshaft.
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That is going to be a monster of an engine Kirk. :clap:
I personally would leave things like decorative columns etc until you have proved it will run. No use going to a lot of trouble if one of your calculations is a bit far out and stops it running. :(
But don't think negative as I am doing, just carry on and I am sure you will have a great runner. :nrocks:
John
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My thoughts are to make the columns a bit longer than spec, so that it is easy to shave off a bit where necessary. These temporary ones are .1" longer than the plan would indicate, but since the thickness of the top plate isn't given I can't be sure what the optimum length will be. I can also mill the top plate thinner as well.
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Both top and bottom plates are the same thickness.
John
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Both top and bottom plates are the same thickness.
John
They are on mine as well. Hiowever the thickness of the bottom plate has no effect on the mechanism. As I understand it, I can adjust the travel of the valves and piston via the threaded connections, but if the plate is too thick or the columns too long then you run out of adjustment room and must reduce the height. Correct?
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Sorry Kirk,
You are perfectly correct, but not a lot. About 0.050", it is there mainly for final tweaks to adjust for for piston and rod length mismatches.
John
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Very soon I will be needing to get all the sliding fits working, and there are a lot of them (valves, pistons, bearings, conrods, piston rods, crossheads). I don't have over/under reamers, so all the holes for these parts have been reamed to same size as the part that slides through them. On my previous engine I had only one valve and one piston/piston rod. My "technique" was to use emery cloth on the sliding part until it could enter (albeit tight), and then use toothpaste to lap it to fit. So far I have done that somewhat with the bearings using some short pieces of drill rod. Is there a better approach?
Also I am wondering if reaming out the crosshead bores to the next drill size would be OK, as opposed to lapping?
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Kirk,
Remember, this engine was designed for beginners, and as such, if the fits aren't very good, it will still run perfectly satisfactory. Just get it fitting to the best of your ability. Reaming to size for the matching rod will be perfectly acceptable.
In fact it is only on engines like flame lickers and sterlings that very fine tolerances have to be adhered to, purely because they have so little power, waste one tiny bit thru leakage, and they just won't run.
If you can get nice sliding fits on all parts, that will do. By the time the engine has a few hours on it, all those superfine fits will be lost anyway. If you can get the bits to fit together and turning without rattling or wobbling, you are onto a winner.
For the bores, if the piston will enter from both ends, and with a bit of oil in there, seal over one end of the bore, and pull the piston out of the hole. If it comes out with a pop, it will be just fine.
The only critical parts are the piston valves, they need to be lapped with a bit of brasso or toothpaste, but I have also seen engines running perfectly well with steam coming out of the top and bottom of the piston valves from new. The Wilesco range is a very good example, like they were made by cavemen with stone tools, but they still run OK. A tight fit on those engines would be about 0.002" clearance between the parts.
John
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I finished the other two temporary columns this afternoon, and started on getting the sliding pieces to fit. First up were the bearings. Here's my alignment/lapping setup:
(http://www.pbase.com/kvom/image/113056641/large.jpg)
I ran it about a half hour with the toothpaste, cleaned it up and oiled it. The drill rod turns pretty smoothly now. I then did a bit of catchup by drilling and tapping the holes for the setscrews on the eccentrics. Next I lapped the bores of the crossheads in the same manner as the bearings. I discovered that one of my crosshead guide bars was slightly bent, so that's a job for another day.
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John's shipment of solder arrived today. Thanks very much. Now I need to get on the ball and get the other necessary items.
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Half to practice with Kirk.
The other half to do the job.
John
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Other than making the other three crosshead guides this morning, I made no engine progress.
I spent most of the day helping a friend move his machine shop gear. He gave me his shop press, all but the hydraulic jack, and it's sitting on my trailer in my driveway right now. He also has a shaper attachment for a BP mill that I can have. I have no idea how to run it, and it's heavy. I believe it mounts on the opposite end of the ram from the head and will cut slots and the like.
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I had the afternoon to play in the shop, and worked on getting the crankshaft and its attachments done.
(http://www.pbase.com/kvom/image/113204777/large.jpg)
The assembly does turn without binding, although I don't have the bearing blocks clamped down really tight. I discovered that I need to enlarge the central baseplate opening slightly, probably .01", as one of the crankwebs is hitting the corner.
If I can get the conrods finished next I can connect up the crossheads and get them lapped in.
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Kvom, your doing a bang up job on this engine and I can't wait to see more progress. I told John the other night that this engine is on my short list. I just may give this a go after I finish the Webster.
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Lookin' good there kvom. :thumbup:
Bernd
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That`s taking shape nicely! :clap:
David D
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Kirk,
Coming along great now, you are doing a wonderful job of it seeing as you are making it a non standard size. I think that there is a mention in the text about making the holes in the bottom plate so that the bearing blocks overhang the edges slightly.
He also has a shaper attachment for a BP mill that I can have
I would suggest you take his hand off at elbow level. The slotting head can be used for allsorts, from cutting keyway slots to square holes. Even if it only gets used once in a blue moon, it is doing no harm hanging out of the way at the back of the head ram. If he comes up with a right angle milling attachment, take his other hand off. That is one bit I would like, but finances are stopping me at the moment.
John
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I got the shaper head home and did some disassembly to check the working/condition. It's not a BP, but made by Lilian Co. in Taiwan. It is missing the clevis that would allow it to mount on the back of the BP ram. I suspect it was permanently attached to the front of a ram as it had a weird setup on the end of the tool ram that looked like it was some some of textile fixture.
I was going to plug it in to see if the electrics worked, but the plug has a different pin configuration than the plug for my lathe does. Motor is 3PH 3/4HP running a 5-sheaf pulley. Stroke is up to 4". There is a homemade control box with e-stop and jog buttons, in addition to the power on/off switch on the head. Pictures can be viewed here if anyone is interested: http://www.pbase.com/kvom/slotting_head (http://www.pbase.com/kvom/slotting_head).
As for the engine, I did a test fit of the conrods to the cranks this afternoon. As I mentioned in an earlier post, I had made them wider than spec since my crankwebs are narrower. Since the crosshead slots are to spec, I will need to narrow that end to fit, and plan to cut a taper in the center. Not sure that I will get to that today as I have shop class this evening.
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Today I narrowed the heads of the conrods to fit the cross heads. I removed the top section and attached the crosshead guides to check for fit. The crossheads went on fairly cleanly, even without any extra "wiggle room" with the guide mounting screws. I did find that one of the guide rods was slightly bent, so I needed to make a replacement. I found that my rear temporary columns were too thick and interfered with the crossheads; so I needed to turn them down to clear.
Then I made one of the link pins to connect the conrod to the crosshead and put it together with the crankshaft, as shown here:
(http://www.pbase.com/kvom/image/113300493/large.jpg)
I am able to turn the cranksahft by hand and move the crosshead up and down, albeit somewhat stiffly. The conrod is still a bit wide and rubs the crankweb. Since I plan to taper the conrods this issue will go away.
Progress might be slow the next week as we will have houseguests.
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Kirk,
That is progress so very nicely. I am envious of this endeavor. Keep up the good work.
Eric
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Coming together nicely Kirk :thumbup: its always good to get start to get things assembled things will really progress quickly know.
Great Job :clap: :clap: :clap: :clap: :clap:
Stew
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Only had a couple of hours or less today. Turned the conrods between centers. I couldn't taper the entire shaft but got reasonably close:
(http://www.pbase.com/kvom/image/113343667/large.jpg)
Here's the setup:
(http://www.pbase.com/kvom/image/113343666/large.jpg)
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My goal for today was to get the entire bottom end assembled and turning. I had to remake both of the smaller crankshaft pieces as they were slightly short and as a result some of the crankwebs were not gripping enough. Lots of disassembly, re-assembly, etc. I finally got it all together, oiled up, and locked in the mill vise. Then I used an electric drill to turn the crank. I ran that for about a minute at a couple of hundred RPMs. Now it's still a little stiff, but I can turn the entire assemblage by hand holding the flywheel.
I then turned my attention to the pistons and piston rods. Cut a length of 3/16 drill rod to size, turned on end down to .155 and threaded it 8-32, which is what I had previous tapped the pistons for. After some polishing on the lathe, I attempted to use the mill to lap one of the cylinders with the piston; all was well for a few seconds until the threads in the aluminum piston stripped out. :bang:
I decided at that point to remake both pistons from steel. :smart:
It's unclear from the plan how much the crosshead end of the rods should be threaded, so I need to do some measurements.
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Somewhat frustrating afternoon once again. I decided to remake the pistons in steel, and spent a fir amount of time turning them and polishing on the lathe to get a press fit. After parting off I attempted to tap one of them with my Kobalt 10-32 tap (since that will match the 3/16" piston rods), and the tap broke. :bang: Too late to switch to 10-24 as the hole in the other was already drilled too large. I also failed at cutting the 10-32 threads on a length of drill rod with a die (threads were slightly crooked). Next time I'll rough cut them with the lathe, and then finish with the die at the end.
Tomorrow is another day.
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Kvom,
Keep the faith, some days ya' just can't get it right. :thumbup: I find doing something else for a while helps. :med: Then the next time you get back to the project it all falls into place.
BTW, I can't wait to see this engine run.
Bernd
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Better progress today in a short 90 minute session. I finished the glands for the valves, where previously I had made the gland and screw. Tonight I drilled and reamed the through hole for the valve stem as well as the two mounting holes. I was apprehensive about this step, but all went smoothly.
(http://www.pbase.com/kvom/image/113498548/large.jpg)
Although I didn't see anything in the plan about where to drill the mounting holes in the steam chest, John's photo shows them fore and aft. That's a job for another day, as well as lapping the valves into both the glands and the valve bores.
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Today I managed to get the valves lapped into the steam chest valve and drilled/tapped the holes for the glands. Otherwise too much time occupied with family visitors.
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Hey at least your making progress. Mine seems to have come to a hault here. :(
Bernd
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Today I milled the steam slots that connect the steam chest holes to the block holes. As mentioned in a previous post, it's possible to mill the slots in the block rather than the steam chests, and that's what I did. I used a 1/8" endmill cutting .11" deep.
I also made V3 of the pistons, this time threaded 10-24 for a stronger joint with the piston rods. The other end of the rods are 8-32 for connecting to the crossheads.
(http://www.pbase.com/kvom/image/113659234/large.jpg)
I managed a better fit on the pistons by taking tiny cuts on the lathe. One is already a tight slip fit on one cylinder; the other will require some more polishing. If I can get the pistons lapped I'll drill and mount the glands next.
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I lapped the pistons so that I have a good sliding fit. I tapped the hole in the crossheads to accept the piston rods, and assembled the block and top plate to the bottom with one piston in its cylinder and the rod screwed into the crosshead. Although the mechanism operates fairly well (able to turn the crank by hand), there is an obvious issue: at TDC the piston protrudes through the top of the block. :scratch:
Since I had made the piston rod to the same scale as the rest of the parts, I am wondering if the 75mm on the drawing is correct. I checked the rest of the critical elements (stroke, length of conrod, height of columns, height of bearing blocks), and all seem correct. Doing some measurement of the piston postions I concluded that my piston rod is .45" too long, corresponding to 7.5mm off the plan's size.
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Kirk,
If the engine is built to plans, the measurements should be almost spot on.
No-one has come back with any problems such as yours, and it seems enough allowance was made on the parts to allow the engine to be tweaked into the correct position for running.
It might be that you are not following the plans in the correct order, and are using the wrong measurements, and also because you are scaling up, maybe the allowances are not correct for your engine. This is always a problem which changing scales
If you have a look at the two extracts, it shows there are two different lengths for the rod. The first to allow the rod/piston combo to be made, the second, where the final lengths have been found. Are you using the first measurement?, as that will certainly give a rod that is too long.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/PE1.png)
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/PE2.png)
If you look at the difference between the two lengths, multiplied by your scaling up, it is showing something close to the error your are finding.
John
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Yes, I missed the second part. Thanks for pointing it out. I wasn't too worried since it was/is going to be straightforward to shorten the rods.
In the meantime I drilled/reamed the packing glands, and will be drilling/tapping the mounting screw holes next.
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Kirk,
I am sure you will get it all running just fine.
You still have time to bore it out bigger and turn it into the monster you are after.
John
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One step forward, two steps back. :scratch:
(http://www.pbase.com/kvom/image/113723308/medium.jpg)
I drilled the gland mounting holes and the block, as can be seen. Why the missing screw? Because there's a broken 5-40 tap in the hole. :bang: So I will get a chance to try to dissolve it out a bit later. In the meantime it's not holding up progress.
After screwing down the glands my piston rod/piston assembly wouldn't go in; turns out the thread on the piston iend of the rod is slightly tilted, so scrap one piston rod. In addition, I had a bright idea that instead of cutting an external 8-32 thread on the crosshead end of the rod, I would drill and tap an 8-32 hole in the end and use a bit of 8-32 screw for the connection. In theory it should work, but the two I tried ended up with the hole slightly off center. At least the threads were straight. I still have enough 3/16 drill rod for 4 or 5 more tries at good piston rods.
It's getting "tricky" to figure the sequence for putting everything together. I believe the best approach to connect the bottom and top sections is to have the crossheads as part of the top, so that you need only bolt the crosshead to the conrod and the top plate to the columns (haven't made the eccentric linkages yet).
You still have time to bore it out bigger and turn it into the monster you are after.
In reality I chose to go bigger so that I could work with bigger parts (I'm still not too confident working at small scales). Given that the displacement will be 3.4 times the original, it may be a "monster" already. The air channels will be only 2.25 times larger in cross section, so it will be interesting to see how much air it will need.
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there's a broken 5-40 tap in the hole.
(http://i16.photobucket.com/albums/b28/CrewCab53/Smileys/wallbash.gif) Dammit, that's a bug**r ..... hope you manage to get it out Kirk ............ the build is coming along very well, really enjoy following it, thanks for the progress reports.
CC
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Ho that annoying breaking the tap :bang:, are you going to try alum to desolve it out ?.
The builds looking very good though :clap: keep up the work, and the post are excellent.
Cheers
Stew
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are you going to try alum to desolve it out ?.
That's my plan.
In the meantime I managed to screw up another piston rod (too short, measure twice, cut once). I think I have enough drill rod for one more shot at getting them right before I need to order another stick. I'm waiting for another "free shipping/$25" offer from Enco.
So I switched to something less stressful and milled out the sides of the top plate in order that the steam chest can join the block now that the glands are in place. Other than the piston rods, the main pieces I need to finish for a first run are the valve linkages to the eccentrics and some temporary inlet flanges, like shred made.
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Here's my results for the day's activities. Rather than worry about getting straight threads on both the piston and piston rod using my crappy dies, I decided to experiment by turning the piston and rod from one piece. The first one worked well so I made the second. :thumbup:
Because there are fairly tight fits on both the cylinder bore and glands, any deviation would tend to bind. By turning them together, they're concentric and (hopefully) straight. I still have to thread the ends for the cross heads, but any issue there can be adjusted by enlarging the mounting holes for the crosshead guide rods to allow "wiggle room".
(http://www.pbase.com/kvom/image/113784743/large.jpg)
In any case, I have a good sliding fit on one cylinder, while the other needs a small amount of lapping.
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I spent some time in the shop today on "fiddly stuff". First order of business was getting the second piston to fit its bore. A few seconds turning on the mill with some fine-grit emery cloth and some scotchbrite got that done. Then I made another temporary column to replace that one I sacrificed to turn one of the pistons. Then the boring job of cutting down screws to attach the top plate to the block. Next drilled and tapped the forks for the eccentric connection, and also milled and drilled the little blocks that go into the slots. Finishing the eccentric linkage will require me to get ready for silver soldering, which is still on the todo list.
I then spent some time looking at the drawings for the steam control. I don't have any flat brass stock thick enough to make the block, but using 2" round the block will be only .06" small. I could possibly use aluminum, although it's not on the "recommended material" list.
Earlier I was cogitating on how the valving works. It would seem that the main points are as follows, assuming the top holes are steam and the bottom are exhaust:
1) For the power portion of the stroke, the piston is near the top and the valve moves lower, opeing both holes. Steam or air enters the valve bore and can go in only two places, the cylinder or via the bore in the valve into the bottom of the valve bore. Since the exhaust hole is blocked from the bottom of the bore by the lower valve disc, all of the work will done by the steam pressing on the top of the piston.
2) For the start of the exhause stroke, the piston is at the bottom moving upware and the valve moves upward. Now the air or steam is forced by the piston back into the valve bore, where its only path is through the hole in the valve piston to the bottom of the bore. Now the exhaust hole is exposed so that the steam can escape. During this time the supply hole is also open, but the stream is confined between the two valve discs.
1)
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Kirk,
It is because of that swap over period that the distance between the two spools has to be spot on. Otherwise you would be having both pressure and exhaust trying to go into the same chambers. That is the reason I showed how to measure the distance between the porting holes and transferring it to the piston valves. Any more than a couple of thou out and you can start to run into timing problems.
Aluminium would be a difficult material to use for the fwd/rev valve casing because you would have to use mechanical fixings to join the pipes to it rather than silver soldering. You should get away with using a mild steel, if you can get the internal finish good enough. The soldering flux I sent you will cope with anything up to stainless steel, so it should easily join copper to steel.
John
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After I posted previously I went and sliced off some 2" brass round and machined a square block from it. I'll start drilling the holes next.
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Today I started on the steam control block, which is the last component needing to be machined and the last assembly that can be completed until I am able to silver solder pieces together. Here's the block and spool, along with the elements of the eccentric linkage completed since the last photo:
(http://www.pbase.com/kvom/image/113895246/large.jpg)
I made several errors in machining the block, none of which I think (hope) will require remaking it.
The first issue was in drilling the mounting holes for the flanges. I was using the vise stop to center all of the holes on the edges, and apparently a piece of swarf or something got between the block and the vise jaw, causing these holes to be slightly off center. To work around this, I will need to offset the mounting holes in the two flanges, but this seems reasonably easy to do.
The second issue was in the size of the 4 steam holes. I just scaled these up from the 4mm plan spec, which means I drilled them 15/64. I should have realized that I would be soldering 1/4" tube into these holes. Since I machined the block out of 2" round stock, the block is slightly smaller than the plan scale would require (1.4" each side vs. 1.47"). This means that the holes are closer to the edge, and enlarging them would make them even closer. However, it appears that I can enlarge the holes to 1/4" while keeping enough material between the hole and the edge.
Finally, I made the center hole overlarge. I entended to drill it to 1/2" and then bore to .59". To save time I drilled the hole using a 1/2" endmill. At least the shank was 1/2" but the flutes made it a 5/8" endmill. So after boring, the hole ended up with a diameter of .645". This can seemingly be handled by making the spool larger to fit, and that's what I did. I also made the spool shaft slightly oversize at 1/4" as I need to find an o-ring with a matching ID. Once I get the O-ring the front and back caps can be machined.
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Kirk,
You might find that the valve doesn't operate quite how it should.
When I designed and made the control valve, the diameter of the spool and porting holes was rather critical when it came to swapping over the inlet/exhaust. Allowing just a small 'dead spot' when in the off position before going to a pressure on position.
You might find that your 'dead spot' will be a little larger before the engine starts to be fed with pressure.
Oh the joys of changing scales and having to wing it.
But at least what you have done is a good job.
The learning curve coming up. Just hope you can get the silver soldering cracked. But if you follow how I did it, and DON'T use too much flux and solder on the joints, you should be ok.
John
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John,
After studying the control block during machining, I now understand how it works. Before I mill the slots I will do some measurements to ensure that they properly connect the inlet/exhaust holes in both positions. I'm not sure right now, but I might need to angle the slots and/or increase/decrease the depth.
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You are quite right on that method Kirk.
When the engine is stationary, the slots sit against the dead area between the porting holes, so effectively blocking all movement of steam or air. As you move either way it connects the ports and depending how much it moves, depends on how much pressure is allowed thru, acting like a restrictor, like your finger over the end of a hosepipe.
John
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I had a full afternoon in the shop making the front and back plates for the steam control. It took a lot longer than I expected as I had to turn both pieces down from 2" brass round, and I wanted to keep the waste of material to a minimum. In addition, the boss on both is a close fit to the block, so some attention and repeated measurements took time. I had located a 1/4" ID by 3/8" byt 1/16" O-ring at the local hardware store this morning, so I had what I needed.
Here's the assembly:
(http://www.pbase.com/kvom/image/113933772/medium.jpg)
I didn't have any 6-32 SHCS so had to use these for the trial fitting. I had been thinking of using stud and nuts here, but standard 6-32 nuts are too large and inerfere with the shaft.
The rear cap turned out to be a press fit to the block, so after screwing it in tio align the holes I pressed it in with the arbor press. I don't see it coming out again. I realized at that point that this part is unnecessary if you have the ability to bore a blind hole in the block for the spool.
Once I could measure the depth of the hole and the size of the boss on the front cap I could mill the spool to length. I probably cut it too close as once the 4 pieces are fastened tightly together there's a lot of friction; I can turn the spool holding it with pliers, but not with finger pressure alone. I imagine there is friction between the end of the spool and the bottom cap as well as the sides and the o-ring pressing against the front cap. Once I make a handle I'll be able to assess if it's too tight.
Here's the parts disassembled. I still need to mill the slots, pending some thoughts on other dimensions.
(http://www.pbase.com/kvom/image/113933773/medium.jpg)
On the soldering front I located local sources for both firebrick and citric acid, so tomorrow I should have everything needed to get started. The first joints to be attempted will likely be the eccentric straps to the linkage blocks.
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Following the recipe in Chapter 5, I made an attempt to SS two scrap pieces of brass together. The good news is that they are in fact together. However the fillet is not as pretty as could be wished:
(http://www.pbase.com/kvom/image/113967107/large.jpg)
In fact it seems that most of the solder remained outside of the joint. The rod is 1/8", and I created a chamfer on the hole with a deburring pen. I'm wondering if either the chamfer was too small or I used too much wire, or the wire wasn't tight enough to the joint. I found that getting a loop or the wire around the rod to be awkward.
I took the piece out of the pickle after 1 hour to take the pic. Can I assume that it will be easier to clean up if I leave it in longer?
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Kirk,
Looking at that, too much flux and maybe a bit too much wire, but because it hasn't penetrated the joint, it might be the correct quantity.
Silver solder requires a gap of approx 0.002" to penetrate down to join the parts together.
With tubing make it a slight slack fit, and very gently flatten the end of the tube into a slight oval. This will make it tight in the hole, but allow the solder to penetrate.
Do the same with solid rod or whatever, but tap the rod with a hammer or centre pop to deform it slightly (only on the area inside the hole, so it will not be seen). Again this will hold the rod tight, but allow the gap.
I normally paint a tiny amount of liquid flux down the hole, and only on the very end of the rod or tube and assemble them all together. You should only see a tiny amount of flux on the surface.
Wrap the wire around the rod or tube like a spring, and cut along it's edge. This will give a series of rings that will easily slide down the tube or rod, flatten them straight before use, you should be able to do it with your fingers, locate it down against the hole. Just use one ring for normal, two rings for a deep hole.
Do not play heat directly onto the flux or solder, only onto the main part, in your case the big bit of brass, somewhere around the other hole, or the end of the metal hearest where you want the joint, and watch the heat travel towards the required joint. As it heats up, the flux and solder will melt and flow into the gap around the two parts. As soon as you see the nice fillet form, take the heat away, wait for a few seconds and then drop it into a quench tank or your pickle bath. Half an hour in the pickle should leave the job completely free of flux and maybe a bit of copper plating over the job, this should easily be polished off.
If the part gets to bright red heat, you've cooked it. Usually a dullish red is sufficient for the main component.
These instructions are for the special flux and wire I have sent to you, other fluxes and solders might react in a totally different way. Especially plain borax, it is not worth even trying, you will never get a perfect joint with it. OK for the 1950's, but not modern day materials and solders.
The main problem with silver soldering is usually too much heat, too much flux and too much solder. Use the minimum you can get away with. If it is not enough, you can always put another drop of flux and a ring of solder and reheat. Just always watch for when the solder flows.
Hope this helps, if not, maybe a change in technique for your style of soldering. You will get it eventually, and once you do, it should be with you for life.
John
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Thanks. I definitely had a lot of flux, and also had the flame too close to the joint. I'll try again tomorrow.
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Kvom,
I've never silver soldered, so take this with a grain of salt. However, having read Bogs post above, and having done more than my share of "regular" soldering (mostly sweating pipe joints), I think it sounds very similar. It's one of those things that takes a bit of practice to get a nice looking and solid joint. It takes time to learn how the heat flows, and where is best to apply it, and how much solder/flux to use.
When my dad first taught me, the pipes stayed together, but they looked terrible. Scorch marks all over, dripping solder, and the possibility of burn marks on the surrounding materials. It also took twice as long as he did it. Nowdays, after 30 years of doing it, I can put most 'professional' plumbers to shame.
The one tip that I took out of Bogs post that struck me the most was the use of flux. Apply it only where you need it, and use it sparingly. That, too, will become more apparent with time and practice.
All that said, I thing you're doing a helluva job on this engine, and a very professional writeup.
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I finally got back in the shop this afternoon. The first order of business was to finish up and test something that a lot of people here have made: a diestock for the lathe:
(http://www.pbase.com/kvom/image/114097441/medium.jpg)
The small part is 1" CRS drilled and reamed .5" and turned down to .65", which is the largest diameter the lathe chuck can clamp.
The larger part started as 1-3/8" aluminum round, bored 1" x .4" deep for the die, with the opposite end turned to .5" to fit the other part. Handles are 3/16" drillrod, and screws are 6-32 (I'll cut them down some later).
I also made a second try at silver soldering, and this time it seemed to go a lot better. Here's the joint after 1 hour or so in the pickle:
(http://www.pbase.com/kvom/image/114097446/large.jpg)
This time I used a very little flux and chamfered the hole manually with a countersink.
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Kirk,
Looks like you have both jobs cracked.
Nice two.
John
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Past few days in the shop have been dedicated to working on the Jeep, after breaking a control arm bolt on Saturday that also resulted in a busted shock absorber. :offtopic:
That said, this morning I took a little while off wrenching to silver solder the eccentric straps. This is the result after 2 hours of pickle soak:
(http://www.pbase.com/kvom/image/114201447/medium.jpg)
I used 3/16" drill rod turned down to .150" on each end.
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Crawling under the Jeep replacing shocks left not much time for any engine building, esp. as I have a sore back as a reult. That said, I spent a couple of hours making some temporary air inlets, copied from shred:
(http://www.pbase.com/kvom/image/114272111/large.jpg)
I also had to re-do soldering one of the eccentric straps. Seems as if the solder did not go where it was supposed to.
Seems as if the only machining needed to be able to try out the engine under air is to fabricate the pins for the eccentric joint and thread the piston rods for connecting to the crosshead, and then I can try to put it together and do the "tuning". If I can get it to run then I'll need to make some feet and try to figure out if I'm going to make the bent copper lines like shred or make the straight flanges. I'd like to make gbritnell's tube bender, so I will investigate that option soon.
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I did make the pins for the eccentric joint, but I also screwed up my pistons. :hammer: I used my new die stock to thread the ends 10-24 only to "discover" that the crossheads are threaded 8-32. Not having any Al stock for remaking the piston & rod as a single piece, I decided to try to make them separately as now I have a chance to make straight threads on the rod. I threaded the 8-32 end on one and it looks pretty good.
Going offroading tomorrow, so no progress until Sunday at the earliest.
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I finally got all the parts made that are needed to try to get it running. I started to assemble everything, and discoivered that one of the threaded holes in a crosshead that connects the piston rod is crooked. :bang: No way it can ever work the way it is.
One option is to make another crosshead. But I'm wondering if there is a way to fill the hole and redrill it. Calling John! :bow:
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Kirk,
The normal way would be to drill out the offending hole oversize, silver solder a little bar of brass in it, then just redrill and trim everything up so that it looks nice.
If you can get a little bit of the same metal into the original but enlarged holes, you can rescue almost anything.
I don't know if you have read the article, but this shows just how to do it. In an hour or so, you should be able to see the finished article after rescue.
http://madmodder.net/index.php?topic=1370.0
Hope this helps.
John
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I was thinking it was something along that line. The hole is about .25" deep, threaded 8-32 and hence ~.160" in diameter.
Once I drill it out, how much solder needs to go with the plug? Am I trying to get the solder to flow all the way down the sides of the plug, or just around the top?
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Make the plug slightly smaller than the hole, say 0.002" to 0.004".
Dip the plug into your liquid flux, paint a bit of flux down the hole, and push the plug down into the hole. If you make the plug longer than the hole is deep, you can always trim it back afterwards. Cut up one coil of solder wire so that it fits around the plug on the surface, it doesn't have to be a super close fit (if you are repairing a tapped hole, use two coils, so that the threads are filled up as well), as long as it isn't too far away from the hole it has to go down. Heat up the main part of the job and you should see when the solder flows down the gap. Take away the heat, let it cool down for a few seconds then quench and pickle for a while.
Dress up the the part to get it looking like it was before the bad hole was put in, then redrill and tap your new hole in the correct position.
All you are doing is filling up the bad hole with metal, then remaking the part from before you made the mistake.
John
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I followed the recipe, and it worked like a charm! :thumbup: Although I was irritated that I needed to do this, I'm glad to know the technique for future use.
Since the hole was both off center (at one end) and angled, I was reluctant to just drill it out, fearing that the drill bit would just follow the hole. Since I have some 1/4" brass rod, I decided to use a 1/4" endmill centered on the new hole and encompasing the old. After a slight chamfer, I did the SS thing. Once I had milled the plug level with the top of the crosshead the repair was practically invisible.
Rather than risk doing the same error again, I clamped the piece in the vise such that the crosshead guide bar chucked in the mill would go straight into its hole, thus ensuring that the new hole would be parallel. After drilling the new hole, I also used the mill to tap it. That's what I should have done in the first place.
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With all the working pieces fabricated, I wanted to put it all together for a trial fit. Here's the result:
(http://www.pbase.com/kvom/image/114464275/large.jpg)
It's not quite ready to run yet, as it's still too stiff to turn by hand. The main culprit is the right hand piston rod, which binds in the gland. I think I will progressively test each eccentric and each piston separately to try to get them loose enough so that the tuning process can be done. The bottom end (crankshaft) does turn by hand fairly easily, and the valves and one piston slide freely when not connected, so hopefully I can get it to run quite soon.
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That is looking real good there, every time you post I think I should do something with mine....
So much to do and not enough time
Like I said, your build is quite something to follow.... :clap:
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Kvom :bow: .......... well done wit the fix .......... nicely done :thumbup:
The rest of the build ain't too shabby either :beer:
Cracking work mate :clap:
Dave
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Thanks for the encouragement. :wave:
I just spent the past hour fiddling with it. The 2nd piston/rod combo is definitely not straight, so I will likely make it once again (#5 if I'm counting correctly). The one piece design seems more likely to come out; since I now have some steel that's over .5" in diameter I think I'll try that again.
With everything connected except that piston&rod, I can turn the shaft assembly by hand, although not easily. I had to quit when my fingers sharter to get sore from pushing on the cranks and crossheads to move them. I suppose I can hook up the electric drill, but since I heard John bad-mouthing that process I decided to wait for advice.
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Nice one Kirk.
That is sure one big engine, comparing it to the size of the can.
I think you have now found out, thinking about doing a rescue can be a lot more gut wrenching than actually doing the job. In fact it can be a massive anti climax when you find out just how easy it is.
Now you have done it the once, all that worry shouldn't be there when you do the next one. You will be plugging holes and redrilling every chance you get.
You are quite right that I don't believe in solving problems by mechanically turning over an engine. Most of my repair work is caused by such actions, you only have to look at my latest repair job. So many worn out parts, before the engine is even running.
I am not saying you shouldn't do it in all cases, as I do it sometimes. Mechanical turning over should only be done on an engine that already turns over fairly easily by hand. I do it to align say crank bearings. Gently have it turning and then slacken the bearing and retighten, allowing the components to find their own perfect running positions. This usually realigns it much better than you can do it by feel.
Are you sure it is not the crosshead guide bars that are causing your problems? With the con rod disconnected, you should be able to push the piston up and down fairly easily. If it tightens up after putting the con rod back, it points to your two cross holes in the con rod not being perfectly parallel. In which case, if they are not far out, you can realign things to run by slackening off the two crosshead guide bars and allow them to find their own position, as the engine is turned over slowly, then a slow and gentle retighten until tight again.
It might not be this, I am just trying to help you fault find before you start to make new parts, that might not be necessary.
Best of luck and well done so far.
John
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Well done Kirk
That engine really looks the business :thumbup:
Now your down to the fine tuning bit you'll soon get it running.
Have Fun
Stew
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That`s looking good now Kirk! :thumbup:
David D
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It seems thje large the engine, the more metal is rubbing together and the more there is friction to overcome. After I took one piston and both crossheads out of the driveline and oiled up everything, the mechanism turns pretty eadily. I did run it on an electric drill for a minute or two.
To reduce the friction in the crossheads more, I opened up the mounting holes in the top plate and polished the guide bars: 3 grades of abrasive tape and then scotchbrite.
In yet another way to construct a piston and rod combo, I made a new rod threaded only on the crosshead end. I then took the existing piston, which fits the cylinder well) and reamed out the threaded hole to 3/16" to match the drill rod. I was hoping for a press fit, but got a reasonable sliding fit. But the rod and piston should be straight. When I fitted the combo into the cylinder and gland both slide well. However when I screwed the rod into the crosshead it became evident that the threaded hole in the crosshead is not perfectly vertical. However, there seems to be enough play in the crosshead guide bars that it will work. So I put some loctite on the piston/and rod, and am waiting for it to dry before seeing if the entire mechanism can be made to turn freely under hand pressure.
Once I get the engine tuned it may make sense to replace the loctite with a silver solder joint.
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Another day of "fiddly stuff" in the shop, interspersed with watching Roddick beat Murray at Wimbledon (sorry you Brits! :ddb:)
Getting everything to turn smoothly with so many moving parts and sources of friction can be a little frustrating. The first thing I noticed was that the flywheel was rubbing on the base plate, as I had milled the flat for the set screw a bit too narrow. It also seems that every time I took something apart to fix or adjustt, on replacement something else would bind. The next item to need attention is the bottom corners of the eccentric straps, which catch on the base plate from time to time.
In any case, I now have both pistons adjusted, and will try to get to the valves this weekend. I have to go out of town for a few days starting Sunday, so I'm not sure when the first trial run will be.
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Finally got back to the shop after some days away tending to family business. I made a pair of support bars from 1/3" square brass bar, to do away with the temporary 4 screws serving as feet. Then back to fiddling.
First fix was to ream out the through holes on the stream chests, as a couple of the screws seemed to be binding and promoting a small gap between it and the block. Then I noticed that one of the cranks was hitting the center opening in the base plate, so I took off the plate and enlarged the width of the hole by .100".
After reinstalling and connecting one connecting rod only, I found that the mechanism would turn easily in one direction, but stick in the other. It seems that the connecting rod angle is greater in one direction and thus induces some binding when trying to raise or lower the crosshead. If I turn the engine upside down then it will turn in both directions, although less easily in one direction.
Currently the guide bars are a smooth sliding fit in the crosshead holes; I'm wondering if reducing their diameter would allow increase or decrease the tendency to bind.
I could also tune the engine to run in the "good" direction to run it in, and then switch the air supply to test out the reverse.
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Kirk,
There is definitely something not square.
The whole engine is built along a common centreline, so the centre of the cylinder head cap is on the same centre as crank. So it should turn equally as easily in both directions.
The only thing that isn't centre line dependent are the four bars that the crossheads run up and down on. That should be your first search area. Slacken them all off, or even take them out altogether, and see if you have the same friction in both directions then. If it still binds on one side, then it isn't the crosshead or bars that are causing the problems. Do not run the engine without the crosshead fully built up, it is that which prevents wear on your bottom cylinder bearing and gland.
John
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Also check your packnuts on the cylinders and valves. They gave me no end of friction trouble since I got the threads a little off-axis-- if yours get tighter and looser as you turn them around the rod, they may have the same problem.
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Shred
How did you correct the problem of the packing nuts? I'm building this engine too.
Ron
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Shred
How did you correct the problem of the packing nuts? I'm building this engine too.
Ron
At the moment, careful tuning. I put them about where they're supposed to be, then rotate them and the matching rod until they both run free. Then a dab of loctite or superglue onto the threads to hold the packnut in place (if not, they gradually tighten themselves to the point of binding). I considered redoing them a couple different ways. Since I've been playing with O-rings a lot lately, were I to redo them, I'd try a Kozo-style O-ring gland (I have his book that discusses them, I have no idea if the design is original to him, likely not given how things are in this business); basically it looks like the packnuts on this engine except not threaded and there's an o-ring seat where the packing goes. A sideways set-screw holds the 'packnut' in place (it must fit well in the o-ring bore)
Since I just went through and re-turned my engine the other night, here's how I went about it-- Starting with an assembled engine that doesn't want to run, even if timed correctly (check this! I messed it up for days of frustration)
1 - Separate the top and bottom halves. Pull the piston and valve pins and undo the tops of the columns. Now you have the crank half separate from the block half .
2 - While you are separating, check the con-rods and eccentric joints are free-- I found that bead-blasting peened one enough to rub. Fix those.
3 - Make sure the crank and bits turn free (dangle it upside down or whatever to keep the con rods and eccentrics from crashing into things). The crank must be smooth and free-running, no binding, or rough spots. Often a little bit of bar protrudes or a crank web or con-rod rubs on something else. Fix all of that, then set the cranks and timing on the bottom end and set it aside.
4 - Now address the top. Without mucking with it (you took it off an engine you thought would run, right?), pull and push the various rods. Run them to the full extent of their travels-- take note of any drag, friction, binding and rough spots. Drag going from one direction to the other at the ends of the travels is a bigger problem than a little running friction between the end points and often indicates an alignment issue.
5 - Starting one at a time, with one moving part (one valve or one piston), fiddle with the adjustments. Bogs left a ton of adjustments in this thing. So many sometimes it's hard to know what to fiddle with. Loosen everything up-- gland bolts, packnut (undo it completely), crossheads, etc and make sure the main bit moves correctly and smoothly. If not, fix it. Then start tightening stuff back up, starting with the gland bolts, then the packnuts, then the crossheads checking all along the way, both ends of travel, fixing the problems that come up.
6 - If there are alignment problems, you may have to drill some holes a little larger to get more wiggle room. If something is way out of wack, you'll probably need to redo it. One adjustment to play with as well is the main block baseplate. That has wiggle room and alignment for the crossheads as well. Pull the glands and pistons all the way out, then put them partway back onto the crossheads, so the piston is just out of the cylinder-- do the pistons line up with the bore? If not, tweak the baseplate over a bit so they do.
7 - Fiddle with the crossheads and get the pistons running as smoothly as possible.
8 - Recheck and reassemble. Time the valve spools and apply air. If your valve spools only run free in one orientation, you'll have to be careful when setting the timing-- set it by screwing the joint, not by rotating the spool.
Hope this helps
- Roy
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Kirk,
1st, what a nice job you have been doing on this build. I think I speak for everyone, we are very grateful you are doing a build log! :smart:
2nd, between what you have learned and the great advice you have gotten from our members you will have it running like a top in no time. :dremel:
:clap:
Eric
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Thanks a lot Shred,
Mine turns over but it is stiff. I haven't made the spool valves and eccentrics or steam chest yet.
I have fiddled with it some but it needs more. I figure I will get the other bits made and try again to be sure I check everything.
Ron
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Some good advice above. Back in the shop this afternoon, I fiddled a little with this and that, but cam to the conclusion that I needed to back up to "square 1". I disassembled the bottom so that I was left with the base plate and the 4 bearings. Turns out one bearing was loose, so I decided to make sure that the entire crankshaft asssembly would be square and straight.
I pushed a 1/4" length of drill rod that I had checked for straightness on the surface plate through the bearings. I tightened down on end bearing and left the others loose. Then I clamped the plate on the mill vise, and using the edge finder zeroed the DRO on the drill rod at the fixed end. I then moved the edge finder to the other end and pushed the rod against it while tightening down the bearing's screws. Now I had both end bearings tight and parallel to the centerline, so I could tighten down the two center bearings. Now I had al 4 bearings lined up and parallel, but the rod was too tight to turn by finger pressure. The DRO indicated that the rod was parallel to the fixed jaw within .001" over its 6 inch length.
Next I applied some toothpaste as a lapping compound and hooked up the electric drill to turn the rod in the bearings. After some minutes it did loosen a bit. I then clamped the assembly vertically in the vise and used the mill to turn the rod, meaning I didn't have to hold the drill trigger down. I ran this for about 5 minutes, and while the rod was not loose I could just turn it with finger pressure. I reassembled the crank components along with the webs, but I still had too much drag. :hammer: So next time I will put it back in the mill and run the rod until I can turn it easily through all 4 bearings. I don't think any other adjustments make sense until the crank is straight with little friction.
As for the top side, I can manually slide the valves and pistons with the gland nuts loose or tight. I suspect part of my previous problem was that the crank pin was not square, causing the connecting rod to twist slightly as it rotates. I did verify with the height gauge that the top plate is parallel to the base plate. Once I have top and bottom reconnected, I can use the DRO to ensure that the block is both centered and parallel to the center line.
Not that much different from debugging software in a way. :scratch:
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This is always the worst part Kirk.
You have everything made within tolerances, but once those tolerances are added together it gives a problem.
It could be such a small thing as the bearing block heights, one on high tolerance and one on low equals trouble. Rather than trying to wear them in, take them off, put them on your drill rod as a block and pushing down fairly hard, swipe the blued up bases across a piece of smooth W&D resting on a flat plate. That will instantly show highs and lows. So then gently flat all the bases down (held as a block and mounted onto the bar in the same order as they are on the baseplate) until you have a nice complete matched set. It only has to have one 0.0005" higher or lower than the others and it will bind when you tighten them up.
Only then should you bed them in with the drill.
Logical and methodical is the way forwards.
You are very nearly there, don't let it beat you on the final straight.
John
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My brain might be a little weak this morning. What"s "W&D"? :scratch:
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My brain might be a little weak this morning. What"s "W&D"? :scratch:
Wet & Dry sandpaper is my guess. A fairly fine grit-- the idea is to scrape the blue (layout die or magic marker would work; I use that a lot for fitting) off the 'low' one. Depending how much they're out, I suppose you could sand the assembled block-o-bearings into shape or flip them over and tickle them with an end mill; just make sure the bases and rod remain completely parallel.
Running-in works for some tight fits, but it will only make alignment problems worse by wallowing out misaligned parts.
A couple other things I forgot to mention earlier was when tuning the assembled engine:
--- I chucked the end of the crankshaft in a small drill chuck (use a tailstock chuck if you haven't got a loose drill chuck running around. I have no idea how I got so many loose chucks.. they must breed under the bench ::)). That is much easier to turn by hand and get a good feel for what's going on than trying to push the flywheel around.
-- Another thing to try when tuning is loosening the crank web on the #1 (awaymost from the flywheel) piston, disconnecting the front end of the engine from the other. If needed, you can make an extendo-rod for the front end eccentric and turn just the front end as well. The engine won't run like that without a much larger flywheel, but you can get a feel for where the problems are.
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I think I have the crankshaft assembly sorted. Following some of the above suggestions, I removed the bearing blocks, keeping themn in order and attached to the drill rod. I placed them on the surface plate, and while pressing down on all 4 with one hand I was still able to turn the rod with finger pressure on the other. Assuming from this that the hole heights were sufficiently equal, my suspicions turned to the base plate. I deburred all 8 mounting holes and also around the sides of all of the plate openings. Then I placed the blocks onto the base plate, still with the drill through the bores, and placed a brick on top of the blocks. I was still able to turn the rod, so I felt that perhaps the problem was solved. I reassembled the entire crank assembly, tightened up all of the screws, and I am now able to turn the flywheel and everything else with finger pressure. :beer:
When I have time again, I will repeat the exercise with the edge finder on the mill to ensure that the crank assembly is parallel to the center line before reattaching the top.
Thanks to all for the advice. :thumbup:
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Short update:
Got it all together, and with a bit more fiddling got it to a point where the shaft turns under finger pressure in both directions. The piston throw is where it should be, but I resisted the urge to start adjusting the valves and the other tuning tasks, as I had limited time to see it through.
I will get to try to turn the columns on the CNC lathe at school tomorrow afternoon, and have spent quite some time writing the g-code to do so. It still isn't coming out the way I want, however.
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My first try at running failed. :scratch:
I went through the chapter on tuning, and as far as I can tell the various components are set as indicated. I tried to adjust the bottom with the engine assembled, but found that tightening the crank webs sufficiently was a problem. Having a set of T-handle allen wrenches would have been an advantage. So I removed the top to adjust the bottom. Of course, when I put it back together things were stickly again. Eventually, as usual, the issue is traced to the crosshead guide rods, which seem to have to be "just so". I decided to ignore the problem for the time being and removed one of the rods from each crosshead.
My bits of threaded rod connecting the valves to the eccentrics were too long, so I had to reduce the lengths to get the valves set in the indicated positions. Once that was done I screwed on the top caps and replaced the blanking plates.
Then I discovered that while the input barb for the engine is for 1/8" tubing, my regulator takes 1/4". Sp it was off to the local hardware looking for a reducer with different size barbs on each end. No luck there, so I came home intending to make one on the lathe. While rummaging in some storage drawers, I found a Schraider valve with 1/4" NP threads, so I decided to put that as the engine input and hook up the regulator used for filling tires. ::)
Since it takes two hands to maneuver the hose, I couldn't see everywhere the air was escaping (engine didn't turn whatsoever). I did see oil all over one of the joints between the block and the steam chest. I need to enlarge the holes in the blanking plates and shorten a couple of the screws to get a tighter seal. I'll also make a double barb connector so that I can run the air hands-free and try to see where the leaks are.
Any other ideas gratefully solicited.
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You seem to be struggling with getting this one going, sorry can't help as you are way, way further than I am with this build.
But I wish you luck....
I was only looking at mine tonight thinking tomorrow I must make some more bits.... :ddb:
My enthusiasm has been swayed by not being able to source material for the block, but I'm still looking....
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Kirk,
I have no suggestions as I haven't built this engine. So nothing technical from me... that said, for me, if I put something down I am having problems with and leave it alone for a few days... I find going back to it is like going back with fresh eyes.
Hope it helps
Eric
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Kirk,
I was looking through your thread for a picture of the engine assembled and found one.
Are you still using the same pillars when you assemble the top and bottom?
I'm wondering if there could be a possibility that one or more of the columns are not the right length and you could be twisting the bottom frame were the bearing blocks are. Try leaving the bottom four or top four bolts some what loose and see if the engine turns over.
It's just a thought and I don't think has been mentioned before.
Bernd
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Hi Kirk
Good advice from Eric put it down for a couple of days and get on with something else, when you pick it up to have another go you'll have fresh eyes.
A good approach is to strip it down and assemble it up again checking each part and assembly as you go for tightness misalignment etc etc correcting things as you go, try and work methodically, a lot of the time it not just one thing but an accumulation of little things that are at fault.
Good luck
Stew
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Thanks for the inputs.
It will probably be a few days until I can get to this again. Since the engine does turn manually as it is now, I am assuming that air pressure in the cylinder would push the pistons down and I would see some movement. Since the hole between the steam chest and the block is so small, I'm thinking that an imperfect fit with the block would let the air escape more easily.
Once I get a better connector for the air supply, I want to remove the top caps and verify that air is entering the cylinder. I'll also try to verify that the tuning setup is correct per the manual. It's not clear how sensitive the setup is, esp. as to the valves.
The 4 temporary columns do have the same length, to within .001". I did start the CNC bling versions this week, but because of limited access to the HAAS lathe I was able to run only the first of the two necessary gcode programs. It will be week after next before I can get them finished.
It would have been too easy if it ran the first time. :scratch:
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The 4 temporary columns do have the same length, to within .001".
Well, that at least it eliminates one problem then. Good.
You'll get it running eventually. Just keep at it.
Bernd
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Since I got my Jeep repairs done early, I had a few minutes to fab up a quick and dirty adapter so that I could run air to the engine. At 40 psi the small tubing blew off the engine inlet, so I think I will looks for a 1/4 x 1/8 barb that will be thick enough for a hose clamp.
In the meantime, I found out the following:
1) The biggest air flow out is coming from the #2 valve gland.
2) There is "some" air exiting from the exhaust ports.
3) When I turn the engine by hand, I feel increasing resistance as the pistons approach TDC. At the top there is enough pressure to turn the crank 180 degrees. So air is getting into the cylinders from the steam chest.
I'll be away all day Saturday Jeeping, but Sunday I can investigate further.
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Kirk,
By the sounds of it, as long as your spools were made to the measured dimensions shown in the article, your trouble just might be timing. Even if things are rather badly made, once the timing is something near, it should run.
When I did my very first runs, the timing was later found to be about 10 degs out, and even at that setting, it ran very well.
It can be a little tricky at first just how to figure it out, as Roy (Shred) found out, but once you can get the grasp of how the timing works, it becomes a lot easier.
John
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If it 'kicks', but doesn't run, when turned by hand I'd say it's most likely timing. Especially if you have to rotate it quite a bit to get it to 'kick' again. That's exactly what mine does when the timing is out.
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After I found a 1/8" NPT x 3/16 hose barb that I could fasten with a hose clamp, I hooked up the engine to the air supply. Although my compressor is set at 125 PSI, my regulator will register a maximum of 45 psi, which I assume is a result of back pressure from the engine itself.
The engine didn't self-start, but when I manually set piston #2 just past TDC and turned on the air, the engine started up and ran for several seconds before stopping suddenly. I repeated this and got another couple of seconds. Since the first two tries, it hasn't repeated. If I do the same thing I get 3/4 of a revolution. Setting piston #1 just past TDC and apply air gets 1/2 of a revolution.
At the point of stoppage there does seem to be more friction (i.e., resistance to turning the crank by hand), but I don't know if it's friction/binding that's stopping it or something else.
A few questions come to mind:
1) Should this engine run on only one cylinder? If so, I could tune one cylinder at a time by removing air supply to the other.
2) Does it sound as if it's the cylinder 1 timing is an issue? Visually, it still looks to me as if the eccentrics are at the top positions when the cranks are horizontal. How sensitive is the vertical setting of the valve? Would it make sense to adjust that before trying different timings of the eccentric (since I have no real idea which way to adjust them)?
3) Does it make sense to try to run in the engine some with the drill at this point?
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DO NOT TURN THE ENGINE OVER BY ANYTHING OTHER THAN HAND OR AIR UNTIL YOU HAVE IT TIMED IN CORRECTLY
If it isn't in correct time, there will be internal pressures built up that are liable to destroy your engine by bending shafts and knocking the crap out of bearing surfaces.
There is only one way you can go, and that is to sit down, study the instructions and the engine, and time it in. It might be a frustrating time for you, but that is the only way to do it. It might take a dozen goes before you get it spot on, but it will be worth it in the end.
John
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A few full rotations is great progress! When mine runs-and-then-stops, what's happened is something (typically the valve spools, but sometimes the crank parts or packnuts or joint pins or crosshead rods or whatever) has moved, rotated, or come loose and either thrown it out of time and/or caused binding. Check on your crosshead rods, valve and crank timing to be sure they're still where you left them.
I don't think perfect timing is critical-- mine is 'sort of' timed at the moment and works ok, but it's got to be close.
You probably don't want to be putting 125 PSI straight into it. I'd start about 60 and lower it as soon as it gets going. A little oil in the airline is good to keep the pistons and valves happy.
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I will just echo what John said, if you've got resistance of any sort it would be crazy to turn it over with a drill. It will just break or bend something and even if not, it won't help at all. I've never used a drill on any engine I've made yet and probably never will.
Try to understand the principle of the valves and the timing they need first, it will be ten times easier to adjust once that becomes apparent.
Nick
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Since it "did" run for at least a few secs, I think my timing might be OK. However, I have taken it all apart and mostly reassembled, taking some of the advice given in prior posts. A few changes:
1) I followed shred's example and degreased the crankshaft pieces and the crank webs. That should allow the webs to clamp more strongly to the crank.
2) Today I bought a set of T-handle allen wrenches at Sears. The numerous 5-40 SHCS are much easier to tighten with the 3/32" T-handle rather than the simple, shorter 90-degree version I used previously. Same goes for the 6-32 screws.
3) Previously the threaded rod was not fixed in the eccentric fork, so I put a drop of loctite there to keep it from turning. I also found that, while the pistons will move easily no matter how they're turned, the valves are vwery sticky in some orientations. When the loctite sets on the forks, I will try to ensure that the valves are oriented in a postion where they slide freely; I will then adjust the valve tuning by turning the fork rather than the valve stem.
Keeping my fingers crossed. :med:
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kvom
Keep at it. You will prevail. :med:
Know this all you trials are not in vain and will aid others in diagnosing their engine problems. I for one will probably benefit a great deal from your post and I humbly thank you "Shred", "Bogs" and all the other posters for the info posted. :bow: :bow: :bow: :thumbup: :thumbup: :thumbup:
Ron
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Kvom it sure will be nice to see that running once your all tweaked in.
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Since it "did" run for at least a few secs, I think my timing might be OK. However, I have taken it all apart and mostly reassembled, taking some of the advice given in prior posts. A few changes:
...
3) Previously the threaded rod was not fixed in the eccentric fork, so I put a drop of loctite there to keep it from turning. I also found that, while the pistons will move easily no matter how they're turned, the valves are vwery sticky in some orientations. When the loctite sets on the forks, I will try to ensure that the valves are oriented in a postion where they slide freely; I will then adjust the valve tuning by turning the fork rather than the valve stem.
/quote]
I'd bet while it was running a valve or two rotated just a little into the 'sticky' orientation and stuck there..
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With the forks loctited to the threaded rod, I went through the top section tuning again, this time trying to ensure that each valve stem stayed in a position where the valve slides easily. I oiled all the places I could think about and hooled up the air.
The engine runs for varying lengths of time when I start it with piston #1 just past TDC, but not otherwise. Eventually it stops. The longest it ran at one time was about 20 seconds, but mostly it would run around 5 seconds before stopping.
There's quite a bit of vibration, and I notice that it tends to loosed the packing nut on the pistons. I was running without the guide rods for the crosshead, but tomorrow I will try it with the rods in place. I'll also recheck the valve timings again.
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Getting closer and closer :thumbup: :thumbup: :thumbup: :thumbup:
I call this stage training the engine to run.
Stew
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You don't want to be running very long without the crossheads in; I think that will cause some pretty odd behavior, wear on the glands and binding as the piston rod is going to get bent every which way instead of running true in the cylinder.
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Kirk,
This is not only very frustrating for you, it is killing me.
I know that if I had this engine in front of me, I could most probably have it running sweet as a nut within no time.
It is very difficult trying to suggest things over distance.
All we can do is share your frustration, and try to help as much as we can.
John
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Yes, very difficult to suggest how to solve the problems / diagnose faults.
The only thing I can suggest is to go back to basic sub assemblies, start from scratch which is what I'd do to make sure nothing was missed. I had to do similar with my stirling engine.
Do the pistons slide in and out easily with their crosshead guide rods and nothing else attached? If not, why not? ... sort that before trying any thing else, there should be very little resistance, even if it has rings of some sort, the breaking friction will be a bit higher but it should move easily once it's started moving.
Do the valves slide up and down easily? If not, sort this out.
Does the crank assembly spin over freely in it's main bearings with nothing else attached? Again, if not, something needs re-aligning or the fit is too close. As bogs said, steam engines tend to be very forgiving, even if poorly made and there is loads of slop in bearings and joints they usually run!
Now does it spin over easily with the eccentrics / rods attached? i.e. is there minimal friction between the eccentric strap and sheave? It should be a close fit but there shouldn't be any tight spots.
Now do the same with the big ends / con rods attached, again there should be no binding at all.
The final test is with the small ends attached to the piston rods. Unless something is binding in the small end or the rod is bent / out of line, it should all turn over easily by hand.
You know the engine runs so ports must be all ok, it's just a matter of making sure the eccentric sheaves lock up positively onto the crankshaft and getting the timing right.
Good luck and well done as you aren't far away, which is why it's so frustrating!
Nick
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:D
Run in the video is with 1 guide rod per crosshead at 40 psi. The engine still needs to have 1 piston just oast TDC to self-start, but once started it will run for minutes on end. Perhaps I need to do the 10 hr. run in that Bogs did. The only change I made since last night was adjustting the #2 valve a few degrees. It then ran for 4-5 minutes until stopping.
I then discovered that the vibrations had loosened the grub/set screws on the #1 valve allowing the timing to go off. On the second long run the same thing happened on the #2 valve screw. I am thinking that the #2 eccentric can be loctited to the shaft without causing any problems. For the #1 valve I might need a deeper notch in the shaft or else a hile drilled into the notch.
I'm guessing the reason the engine won't self-start in all positions is that there is still a fair amount of static friction to overcome, and that a half-stroke of the piston doesn't generate enough momentum. It might be interesting to mount a heavy metal disc on the end of the shaft. One area of friction that I'm aware of is between the eccentric clevis and fork. I think a bit of filing on each will help the next time I do a disassembly.
Another thing to try is moving the air to the lower inlets to see how it runs in reverse.
John, you can relax a bit now. :beer:
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Way to go Kirk, that is wonderful news.....looks like it's going like the clappers there.... :clap: :clap: :clap:
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All right Kirk
Way to go. You out lasted the engine. :beer: :beer: :beer: :beer:
:ddb: :ddb: :ddb: :ddb: :ddb: :ddb:
:nrocks: :nrocks: :nrocks: :nrocks: :nrocks:
Bernd
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Thanks Kirk, I will sleep soundly tonight. :lol:
I still think that your timing is slightly out though. But now you have it running, you can tweak until you get it spot on.
Give it a drink of auto engine oil every ten minutes or so, down the airline to the engine, and let it bed itself in for a while.
A real good result. Apart from mine, yours is only the second to be shown being built with a running result at the end. Shred beat you to it, but not by much.
Yours is a bit special though, you made it BIGGER.
Very well done. :clap: :clap: :clap: :clap:
:ddb: :ddb: :ddb: :ddb:
Bogs
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tweak until you get it spot on.
Spot on meaning it starts in any position?
Give it a drink of auto engine oil every ten minutes or so
I have been using air-tool oil. What's the advantage of auto oil?
Apart from mine, yours is only the second to be shown being built with a running result at the end.
Since you built two, mine is only the 4th. :bow:
you made it BIGGER
I have an idea that bigger is easier, aside from accumulating materials. Other than the brass for the reversing valve and the legs, plus the drillrod I didn't pay for any of the material. The scrap bin at school was very handy. For tools that I didn't have at the start of the project, I had to buy some threading dies, a tap or two, and a 1/2" reamer for the cylinders. I was able to borrow the slitting saw for the crank webs and lathe dogs for turning the connrods. I also got the gift of the silver solder from you.
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Kirk,
The engine should stop and start from any position, in either forwards or reverse, there are no dead spots designed on this engine at all. The only time it could fail to start is if running on steam, there might be a hydraulic lock caused by condensing water, or if on air or steam, whilst the engine is bedding in, internal frictions have to be overcome for the engine to start. Both mine tick over and run on 5 psi. But they have had a lot of running time. The last steam show I did, they got about 12 hours each spread over 2 days.
If the cranks are exactly 90 degrees to each other, and the timing is set at exactly 90 degrees lead to each crank, then there is always a power stroke, either up or down that will start the engine in motion.
Auto oil is much thicker, air tool oil is like 3 in 1 oil, and is really too thin for bedding an engine in. It will allow more friction to build up due to it having a much thinner film layer.
You are correct, yours is the fourth, but second if you exclude mine.
You definitely went the hard way, not only were you converting from metric to imperial, but you upped the scale as well.
Unfortunately, it will only have the same power or even less than the smaller one, as you kept the bore sizes the same as the smaller one, but increased the moving masses and friction by going larger.
But, you gained a lot of experience, that is the biggest plus about your build.
John
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Good job. Sounds like a real powerful one, too.
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The bore is less than 1.5x the scale diameter, but the area of the piston is 1.61x normal scale. With a 1.5x stroke the displacement is 2.42x the original. Had I scales the bore proportionally the displacement would be 3.38x.
I will try the motor oil tomorrow.
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:beer:
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Well done Kirk
I bet you've got a grin going from ear to ear and so you should.
:clap: :clap: :clap: :clap: :clap: :clap: :clap:
:thumbup: :thumbup: :thumbup: :thumbup: :thumbup:
Stew
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"Well done that man" :clap: :clap: :clap: :clap: :clap: :clap: :clap: :clap: :clap: :clap:
:headbang: :headbang: :headbang: :headbang: :headbang: :headbang:
With all the work that you've put into this build, there must be a huge sense of achievement to get it running.
Well done :thumbup: :thumbup:
Tim
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Very well done Kirk! :thumbup:
:clap: :clap: :clap: :clap: :clap: :clap: :clap:
:ddb: :ddb: :ddb: :ddb: :ddb: :ddb: :ddb:
David D
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Good on ya Kirk, lovely to see something you built run, I'll get to that stage eventually!
Well done.
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Looking back on this thread I see that the first part (eccentric) was made on April 29, so it was just shy of 3 months from start to getting it to run. I estimate I have about 150 shop hours so far. I purposely limit myself to 4-6 hours max. time in the shop at a time to avoid getting burned out.
I have to give John props for the design, plans, and construction book, as well as the ongoing advice on this forum. I can definitely recommend this build to anyone looking to "step up" from wobblers. None of the parts is very difficult to make given some care and accurate measurement. My having DROs on the mill and lathe definitely made things easier/quicker.
I don't have any pics like shred's of the practice parts. I remade the pistons and rods 5 times, mainly because I couldn't get them straight enough :bang: Having a tailstock mounted diestock for the lathe is really a must.
I still have a ways to go to get this finished and polished up. Stay tuned.
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Well done! Fantastic result! :thumbup: :clap: :clap: :ddb:
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Today, following Bogs' recipe, I dosed up the air supply with 10w-30 motor oil and ran the engine intermittently for a little over an hour. At the same time, the exhaust and leaks lubricated my milling vise quite nicely. ::)
There were any number of things that would cause it to stop:
1) The mounting screws for the guide rods would vibrate loose, allowing the rod to fall down and jam the crank.
2) The piston gland nuts would vibrate loose. I had to cinch them up tight with a wrench eventually.
3) One of the screws holding the #2 steam chest loosened, allowing the steam chest to tilt slightly and jam the valve stem.
Nevertheless, after an hour the engine was running nicely on 30 psi. It needs enough air to cause the compressor to run continually, so 1 hour was about all I could stand.
After the last run, I noticed that the jam nuts on the valve stems had vibrated loose, so I suspect that one of the valves has rotated to a sticky position. That's something to check the next time I run it.
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:clap: :clap: :clap:
Nice job Kirk! I remember when you started posting over at HMEM... You have come a loooooong way since then eh? :smart:
You deserve a banana!
:ddb: :nrocks: :ddb:
Eric
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And have another banana on me Kirk, nice job :ddb:
CC
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Kirk
You might try putting a piece of dental floss in the piston and valve packing gland with the end sticking out, then install the gland nuts. Sort of a poor mans friction nut. It might keep them from loosening up as you run it in.
When I made my QCTHs I put some in the height adjustment screw and it keeps it from free turning when I change out holders.
Ron
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I finally was able to get the columns made on the CNC lathe at school.
(http://www.pbase.com/kvom/image/115788060/medium.jpg)
On the left is a temporary column, followed by one that's been tapped and the others I need to drill and tap. To get the same profile manually would have required grinding some form tools, plus cutting the taper either with the TA or the compound. This was my second project for actually making a part, and the first that I designed myself. There were two g-code programs:
The raw material was 5.5" lengths of 1" 6061 rod. For the first program, the rods are clamped in a 1" collet with 2" exposed. This program faces the rod and turns the 1st .5" down to a diameter of .49". It then centerdrills to form a 60 degree chamfer, then drills 3/4" deep with a #36 drill for later tapping 6-32.
For the second program, the pieces are clamped with 4.5" exposed. A live center is used in the chamfer created in step 1. The program turns the profile using a 3mm round tool, then parts off the column at a length of 4.16", a few thousands overlength.
To finish for mounting, I chucked the column on the lathe using a rubberflex collet, with the bottom exposed. I could then face the bottom and drill and tap for the 6-32 mounting screw. I then tapped the top end at the workbench. Once I do all 4 I'll use the height gauge to measure each one, and then face so that all 4 are the same length to with .001.
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That should finish it off nicely! :thumbup:
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VERY VERY NICE !! Always like seeing multi-cylinder engines being built and running. Double the eye-candy with double the cylinders !! :thumbup: :thumbup: :thumbup: :clap: :clap: :clap:
Mike
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Getting a little more done on this. I drilled/tapped/mounted the new columns, and also made a pair of flanges for the input/exhaust pipes. I decided to make 1-piece flanges rather than separate, and I think that will make the fitting a bit easier when I finally get the little tube bender finished and can attach the valve assembly.
(http://www.pbase.com/kvom/image/116610775/medium.jpg)
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looking good kvom :clap: :beer:
i have looked at the plans for this engine and would like to start building one but i have so many other things to finish.
it will likely be next winter before i can start building it :dremel:
keep up the good work :thumbup:
chuck :wave:
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Kirk, the little 'ducks is coming along really well. Looking very good :thumbup:
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After some weeks where shop hours were dedicated to automotive chores, I got some time in to get onto the project backlog. Unfortunately my photo site, pbase.com, has been down for the past 3 days, so I won't be able to share visuals until they come back up.
The first task was to finish the mini tubing bender that had been languishing as an incomplete box-o-parts for several weeks. I made the last few minor parts, cobbled it together, and was able to bend 4 lengths of 1/4" copper tubing that are to serve as the connections from the spool valve to the engine. I also made the two small flanges for the input and exhaust tubes. And as the last part needing fabrication, I made the valve handle.
Now I pulled out the silver solder "kit". First, I needed to plug the two holes in the top and bottom of the valve body. I turned a couple of small brass rounds with a flange to ensure they stayed put during soldering. The solder job went smoothly, and I then milled the plugs flat to the top and bottom of the valve.
Then, like Bogs, I used the engine itself as a jig to hold the air tubes in place while I solders them to the valve. One all four were soldered, I proceeded to solder the other ends to the flanges. Here I had a couple of problems, in that some gaps remain around the tubes. Seems the solder stuck to the tubes rather than falling into the cracks.
So now I need some advice on how to seal the gaps. Should I just apply some more flux and some pieces of solder and reapply heat, or is there more to it?
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Kirk,
Once you have some pics up, show us the problem joints.
It might just be a case of putting the job into the pickle for an hour or so, drying off completely with a flashover with your torch, then a little more flux and solder on the joint. You need to get rid of any old soldering flux deposits before proceeding, otherwise the joint will be contaminated and the fresh solder might not 'take'.
John
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Here's the photo log of progress on the engine.
First, the mini tube bender for making the 90 degree bends in 1/4" tubing:
(http://www.pbase.com/kvom/image/117677678/large.jpg)
A trial fit once the tubes are trimmed:
(http://www.pbase.com/kvom/image/117677684/large.jpg)
The side flanges with some temporary tubes for fit:
(http://www.pbase.com/kvom/image/117677689/large.jpg)
The top/bottom plugs soldered:
(http://www.pbase.com/kvom/image/117677694/large.jpg)
And them milled flush:
(http://www.pbase.com/kvom/image/117677698/large.jpg)
The tubes soldered into the valve body:
(http://www.pbase.com/kvom/image/117677702/large.jpg)
The handle for the valve:
(http://www.pbase.com/kvom/image/117677708/large.jpg)
Valve after soldering tubes to the flanges:
(http://www.pbase.com/kvom/image/117679672/large.jpg)
And the problem gaps where the tubes enter the flanges:
(http://www.pbase.com/kvom/image/117679667/large.jpg)
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Kirk,
Very nicely done indeed, there is not much wrong with your soldering technique at all, in fact it is spot on.
You have soon picked that up.
For those semi soldered joints, just do as I suggested, pickle them for a while, reflux and wrap a bit more solder around the pipe, say 1.5 turns. Don't let the main heat touch the pipes, just the flanges.
John
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I finally got around to resoldering the flanges and finishing the reversing valve. Only took 4 months since the last post. :scratch:
But here is it, ready for disassembly and some polish. I am going to remake the blanking plates.
(http://www.pbase.com/kvom/image/121258618/large.jpg)
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Well done Kirk, that's turned out well. I look forward to seeing what it looks like when polished up :thumbup:
Tim
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I've been wondering what a "paddle duck engine" was ever since I first wandered across the reference, and I have to say, having seen it, you are making a serious job out of it, and your's is looking great. Your tubing bender picture is an improvement on the one I was going to make for the tubing for my radial engine, so I think I'll use your design and get better results.
I was once a certified micro miniature electronics repairman, while serving in the Marine Corps, and was taught the secret to soldering is 95% cleaning, and the remainder careful workmanship. When soldering for strength as opposed to electrical work, tinning the whole site which you want solder sticking to, is the best preparation, both the bar, with its hole tinned, and the ends of the tubing. Once this is done, you will never have an inclusion or break in the soldering job. Chalk can be used to limit where the solder runs to, including the sticks sold for marking out steel or rusty metal. This works with pretty much any kind of solder including "hard" silver solder as well as soft.
That's a great looking engine, I can't wait to see and hear it run!! :ddb:
mad jack