Arnold building the "Little Blazer"

[arnoldb]

With a couple of compressed air/steam engines under my belt, I feel like a foray into the world of flame lickers...
I have quite a couple of plans available, but for most I would require items (mostly small ball bearings) that are unobtainable locally, and hence require running the gauntlet of E-Bay and poor and unpredictable postal services to Namibia.

I nearly glossed over Phil Duclos's Little Blazer because of some of the small screws needed, but then I realised I could make them myself, so I started sourcing raw materials:

Bits of the above will go into the build.  The big round piece of aluminium is to make the base from; I can't find a rectangular piece of suitable size, and the feeler gauge will have its one blade sacrificed for the valve spring.

The build was actually started last Sunday; I milled the big round bit of aluminium down to form the rectangular block from which the engine base is to be built  First roughed  it out to a rectangular block:


Measured and marked up final dimensions:


Finally down to size and as square as I have ever gotten anything...:


Then I calculated and marked out the bit that has to be faced off at a 20 degree angle.  Nothing fancy; just some trigonometry to calculate offsets, and draw a line.  I used the height gauge on the mill vise to check that I clamped up the block at the required angle:


And faced off with the flycutter:


I used a small file to de-burr the cut edges while still clamped up, and then used an obsolete needle valve chucked up in the dremel chuck adapter to locate the one corner as accurately as possible by eye; Mr Duclos used a wiggler's needle for this step:

The mill's x and y dials were zeroed at this point for the next steps.

I dialled in the 12.7mm offsets needed on both X and Y and spotted the location with a center drill, then drilled about 13mm deep with a 6mm drill:


This was followed by a 16mm drill:


And finally the boring head to get the hole to 17.4mm - I used the 12-19mm telescopic gauge to measure; at the larger end of it's range, it's not entirely necessary to get its handle in alignment with the bore of a hole, as long as it's head is kept square to the bore central axis:


The boring was followed by offsetting the Y axis further to locate the position for the valve rod guide, and spotting and drilling a 2mm hole for the valve rod:  

I hope this does not bite me in the back; Mr Duclos specified a #49 drill which is between 1.8 and 1.9mm - and I decided to go for a 2mm valve rod...  It will be a bugger to turn up a bushing if needed  

Next followed some more markout; a lot of it was just to help me visualize the base and to double-check that things were still going to plan...:


More milling followed; pretty much following Mr Duclos's instructions:


The next photo was originally only intended to show how I use a square in the vise to set up a part a distance from the bottom of the vise when I don't have suitable parallels around, and accuracy is not of the greatest importance.  When viewing the photo on-screen however, I noticed some additional details with some valuable personal lessons behind it.  Original intent: I have a small flat square with a wide edge on the short end.  By putting the wide edge on the vise bed, and pressing it down with my middle and ring fingers, it is held fairly secure to the vise bed.  Then I use my thumb and forefinger to squeeze the part to the vertical edge, and tighten up the vise (The milling cutter is quite a way away from my hand and not dangerous here):

Now the anecdotes; there's three here.  
1.  Just to the right, and slightly above the bottom of the milling cutter is a scar on my hand.  That has been there for about 15 years, and the damage was done by my "small" 115mm (4.5") angle grinder.  I was making a security gate for a friend and was grinding away my (bad!) welding marks; using the hand in picture to hold the gate, and my right hand to run the grinder.  I was getting tired, and it only took a minute lapse in concentration and the cut was done; it could easily have been much worse, but fortunately not.  I have never since worked my "small" grinder with one hand only; the work gets clamped down, and both hands works the grinder.  If I feel I'm getting tired, I stop - a grinder tires one out quickly.
2.  If you follow the very top of the square from left to right, about a quarter of the way just above the edge there is a small scar on my hand.  That was done by a thin Dremel cutting disc breaking; my hand happened to be in line of the disintegrating disc.  Personal lesson learned; keep as much as possible of body and soul out of the spinning line of stones and discs - even a small Dremel needs to be treated with respect.
3.  To the left of, and below the top of the square, there's a scratch on my finger.  Shrek the African Gray parrot did that this morning; he was in a bit of a bad mood.  Lesson - animals (and people!) have bad moods; these I just have to accept in the spirit of love  

Enough digressing and back to the build.
Once again the impromptu center finder I mentioned earlier comes into play to locate the center for the rounded bottom "inside curve" of the base:

Though it looks like I'm only working to one line, there is a tiny prick mark left by the compasses when I did the last layout.  If you don't believe me, click here for a bigger photo.

A 6.5mm hole was drilled, followed by a 19mm (my biggest!) drill:

I was concerned about the big drill doing an interrupted cut, but as quite a lot of its tip had to follow the pilot hole, things went well.  The drill was still under size, so if it strayed a bit, there was not too much of a concern.

The 19mm hole was then opened up to 22.2mm with the boring head:


Up to this point, I've been fairly brutal with the workpiece - taking fairly big cuts at good rates of feed.  For the next phase I slowed down a bit, as workholding was becoming less secure.  After de-burring, I started by using a square to set the workpiece vertical to the angled face in the vise; once again using the method with the square - and - fingers mentioned earlier, with the centerline of the bore from the previous step above the vise jaws, and some old business cards between vise jaws and the workpiece to get things as tight as possible.  Then I milled down the back to meet the bored hole - as the face end is getting thin and high above the vise, I took just 1.5mm down-cuts at a time staying away from the final thickness:


The other side followed:


Milling down the "step" in the base proved problematic for workholding.  As the workpiece was getting whittled away, there were less - and more irregular - features to clamp down.  I _COULD_ have mounted my mill vise's swiveling base, but getting everything in tram would have required a lot of fussing about.  So I gambled on a "back-to-basics" method.  I clamped the workpiece directly to the mill table with thick bits of paper between it and the mill table, as well as between its top and the clamp.  Once again I used the small square with the offset base to align the face:

The single clamp point is far from ideal - but I didn't want to clamp through the bored hole in the face, as clamping there could distort it...

Then started milling away - lightly.  Several passes in Y to get to depth, offset X and repeat the Y  Part-way through:

Before I hit final dimensions, I checked with the square again - just to make sure nothing moved.  It didn't  

Before removing more metal from the base, I decided to drill and tap the mounting holes, as well as the mounting hole and screw-down for the retainer clip for the burner:


And tapped that lot - all M3 instead of 1-72 and 2-56; I deviated from the plans a bit for "comfort"   :


At this point, and about eight straight hours from starting the day's machining, my cellphone rang.  I tried to answer the workshop electronic calculator... - That seriously meant time to pack up; I don't want any more scars.  So, no more machines, but I still wanted to do a bit more...

The base needed rounding over around the cylinder mount.  Mr Duclos does that using a rotary table on the mill.  Filing buttons would do as well, but machining was out for me at this stage, so I deeply scribed the curve using a conveniently sized bit of rod as a guide and trimmed the excess off with a junior hacksaw.  Then filed roughly to the scribed line with a big coarse file:


Followed by my favourite "smallish" file - down to the line by eye and judging "squareness" by eye as well:

Took all of 5 minutes to saw, coarse file, and fine file down; would have taken longer to turn up filing buttons!

A quick "lick" around the filed edge with some emery wrapped in the self-same rule in the next photo, and that's where I packed it in for the day:


I've actually had a very active day in the workshop; it feels like I've been to the gym from just contorting to check angles for holes and so on.  And of course, cranking the mill wheels - lots of exercise there! -  :big:

This was a bit of a marathon post; I value all questions, input and criticism!

Regards, Arnold

[j45on]

Great post 
I shall be watching with great interest 

[Rob.Wilson]

Hi Arnold


I looked at the bill of materials for this engine build ,,,,, it did not list a blue fluffy towel     


See you have already put the hight gauge to good use 


Rob 

[Stilldrillin]

A lot of fine work has gone into that one component Arnold! 

Love your humerous comments too..... 

Good luck with the rest of the project. 

David D

[Dean W]

Hi Arnold; 
A lot of work already.  That one part has a lot going on.  Thanks for your usual good pics and words.
BTW, nice height gauge and boring head, too.  Nice work all 'round!

Dean

[sbwhart]

Cracking bit of work that man 

Are you following book plans or are they available on the net ?.

Stew

[arnoldb]

Thanks Jason 

Rob, thanks mate -  Must have gotten confused with a Ford Escort dashboard project; hence the fluffy towel  Wonder where I put the fluffy dice to hang from the rear-view mirror .  The height gauge is a treat - really makes life a lot easier 

Thanks David - have to try and make it interesting 

Thank you Dean.  I love the boring head; and that one's mostly your fault  .  The home-made bits of kit are getting ever more useful - not as nice as shop bought tools, but they have character

Thanks Stew  .  Its from a book - "Two shop masters" by Frank McLean and Philip Duclos.  Photocopied pages for doing the metric conversion thing on and use in the shop.

Time to finish morning coffee and hit the shop again 

Kind regards, Arnold

[madjackghengis]

Hi Arnold, having built one of these myself and taken close to two decades to get it to run, I had to comment.  I built mine from the article in the Home Shop Machinist, which I believe is half size compared to the one you're building, have you decided what your cylinder will be made of and what you will use for piston material?  For my half inch bore model, I've made four cylinders and six pistons, using 6061T6 aluminum for the cylinder, and bronze bearing material for pistons.  The aluminum tends to score, and I can hone out the bore four or five times and sand the burrs off the piston before I have to make new of each, so when the piston stuck yesterday, when I was running it just to sort of end the day, I bored the cylinder out an extra eight thousandths or so, setting it up in a four jaw chuck and centering the bore first, and have machined a piston out of graphite, out of a spare electic motor brush in fact, and will be making the sliding valve out of the same graphite from another motor brush.  I hope to get more than an hour's total run time between rebuilds with the graphite but I've never run it in aluminum before.  I look forward to seeing your's run, I made a mess of the cam, machining it in a four jaw instead of on a rotary table, and translated numbers wrong, using a diameter instead of radius, and having a cam which was substantial the wrong profile.  As to the spring for the valve, it does not have to be strong, just enough to keep the face of the valve flat and no more spring necessary, my spring is made of a piece of copper sheet about fifteen thousandths thick, and I had to cut off all the excess and reduce the pressure to almost nothing to get the bronze slide valve friction down to almost nothing, getting my little version to run, so start with just enough pressure to keep the valve aligned and flat.  I'm looking forward to seeing the difference in getting your larger version running, versus mine, but considering only the work after I figured out all the errors I made, as they don't figure in the virtues of the design its self.  I can hardly wait to see the video, you're looking very good so far. mad jack

[arnoldb]

Thanks Mad Jack    I don't know if you're talking about the same engine; I wouldn't like to build this one in half size - Well, not yet anyway; I would need some 1mm taps first!
I'm making the cylinder from cast iron and the piston from phosphor bronze; I don't have access to graphite for the piston yet.  Thanks for the pointers!

On to today's bits.

Phil specifies the clamping screw on the collar as a 1-72 cap screw; I don't have anything that small, so I settled on an M2 machine screw.  Head clearance for this screw is 4mm - and the collar is 4.7mm wide; that leaves 0.35mm either side; loads of space    - as long as I could pull it off accurately.
I used the sharp pin to locate the edge of the vise jaw on Y, zeroed it and dialled in 2.35mm offset.  Then I located to the center scribed line for the X and locked that:


Then with a 4mm center-cutting slot mill, very gently bored down to 1.5mm above the depth mark:


Next followed a small center drill - just a shallow hole with its tip:


That was a guide for the 1.6mm drill that followed - about 10mm deep for tapping M2:


A 2mm clearance drill followed; just 2.5mm deep, and then I tapped the holes - still in position, but with the collet holding the small drill arbor loosened to allow the arbor to rotate and slide in it.  I just chucked the tap in the drill arbor and twirled the shaft with my fingers to tap the hole; it does not take a lot of torque to thread M2!:


As a final step, I slit the collar with a 0.5mm slitting saw:


Some more layout followed:


I used a 10mm mill to clear the big bit of excess away - just by eye to the lines, making sure that the bottom met the curved section in the base nicely:


To mill out the section between the two bearing columns, I had to revert to a 6mm mill.  The 10mm is too big here, and I thought I had an 8mm long series.  Well, so much for "thought"  :

  Notice the ding on the top of the collar ? -    - I forgot to check clearance for the collet chuck and left too short a bit of the cutter sticking out, so I ran the collet chuck into the collar...  Fortunately not to bad; the chuck lost some black off it's closing nut, and the ding was very shallow and easy to file away.  I just hate that sudden extra "grrrr" noise!

Then I milled the back end to 10 degrees as per plans:


For laying out the center line for the crankshaft, I needed a plug turned up to fit closely in the collar.  This calls for a "scrap" bit of "something - but I couldn't find any, so I used a good bit of aluminium.  It was really nice to get back to the lathe for a change    :


That piece was then just parted off and clamped up in the base collar.  Phil recommends clamping the base to an angle plate for the next step; I don't have one, so bodged it by holding the piece against a square  with the base edge firmly lying on the glass plate.  Then get the height at the top of the plug, subtract its radius, set the height gauge to that, and scribe the center line on the one column:

It looks as if the base is not sitting with it's one edge flat on the glass plate in the photo; that's an optical illusion.

The other "crossing" center line is easily marked from dimensions, and this is the result:


The piece was then set up squarely in the mill again, and the axle bearing holes drilled at 2.9mm for reaming out to 3mm later.  At this point it was 14:00 and my elderly neighbours like to take a Sunday afternoon nap.  Their bedroom is very close to my shop, so I shut up with the machines for a while, and brought out the small needle and riffler files to clean up the base a bit - after I used a larger file to round off the one sharp edge and the tops of the bearing columns:


A while later, and after some 320 emery followed to get a brushed finish, I ended up with this:


Well, while posting up I noticed it's not quite good enough yet; the one bottom mounting hole came through the base between the pillars    - so that needs to be fixed.  And as always, one sees some more places that requires finishing off - the camera is pretty good at showing those up!

Once I heard the neighbours were awake, I started off on the cylinder.  A bit of 30mm cast iron - faced off and center drilled:


Then turned down to 1", and cleaned up a bit with emery:


The neck turned down and a trial fit to the base; it had a bit of a step at the back that needed further relieving, so it appears a bit short:


Turning the fins on the cylinder was a no-brainer; much to my surprise    I thought I'd have to make a turning bit, but found one among my assortment.  BONUS - it was already sharp and suitably profiled for cast iron   And its tip was 1.6mm thick! - Well I needed 1/16" - 1.59mm. That half a thou won't make much of a difference    And another bonus; my lathe's leadscrew is 8 TPI, so one turn per fin; no messing with numbers!  Fins started:


And done - 15 minutes later:

It took longer to get in there with some emery to get a bit of shine showing up in the bottom of the grooves than it did to groove them 

Then I bored the cylinder...  I'm not entirely happy with the finish inside, so I suspect a lot of lapping will be required later.  Not sure though, as cast iron is deceptive.  Brass and aluminium will machine to a mirror finish indicating that it is smooth, while cast iron can be very smooth and still look dull...:


I parted off the cylinder .5mm over length for clean-up - then chucked it with some paper to protect the finish on the fins, and cleaned off the back side:


The cylinder to this point; I quit while I was ahead today  ;) :


And assembled thus far:


I don't think there will be any progress during the week; so most likely next weekend only.

Thanks for checking in!

Regards, Arnold

[raynerd]

 

Amazing! I`ll be waiting for the next instalment...excellent job.

[Stilldrillin]

That was another good day's work Arnold! 

David D

[sbwhart]

Great bit of work Arnold and really well shown.

 

Thank you.

Stew

[Brass_Machine]

Finally caught up with this one. Very nice work Arnold. Love the side comments 

Gonna be watching this one.

Eric

[arnoldb]

Thanks Lads; much appreciated

Kind regards, Arnold

[arnoldb]

Finally, some more progress 

I clamped the cylinder lightly (to prevent distorting it) in the mill vise on top of one of my crude parallels.  Some cardboard serves to both protect and to ensure a better grip. Then I used the height gauge to find the top, made a note of the reading, and marked out a line to depth for milling away the port face:

Of course, I first cleaned the mill table well of any swarf in the area where the base was located before doing this!

Then I milled away the port face.  As the cylinder was clamped lightly, I milled away the face in small increments; 0.5mm max depth of cut a t a time:

All the passes were done in line with the cylinder bore to prevent it trying to rotate in the vise.  When I got close to the scribed line, I checked again with the height gauge, and fed in the last required amount using the Z handwheel scale.  As this pass was very light, I opted to do the last cuts perpendicular to the cylinder bore, as it would make it easier to remove the tooling marks later.  As a final step, I also milled the clearance flat for the valve pushrod.

I very lightly marked out the location and size for the valve port with the cylinder still clamped:

Very lightly, as I didn't want deep scratches to have to remove later on!

I went to my engineering suppliers this morning, and returned with a couple of new bandsaw blades and some milling bits, and while there something kept tugging at my mind and wouldn't quite surface.  At this point it did  - I needed a 3mm milling cutter for the valve port, and I didn't buy it... 4, 6, and 8 mm, but no 3mm     By then the shop was closed as well  - So I settled on using the 2mm cutter I have, and milled the port - widening it to 3.2mm with a couple of edge passes:


While milling the port another thing raised its head...  I'm a pretty easy going person, but one thing I HATE is squeaks.  And the mill's y-travel handle had started to squeak - deep in the inside   .  I removed it, and tried getting some oil in there, but it just wouldn't go down and stop the squeak, so, on to the lathe, and drilled a hole into it from the other end:

A drop of oil in there, and squeak sorted     It's a pretty crappy plastic handle, so I just might make a nicer metal one in future.

Back to the build...  I have the princely sum-total of 2 slitting saw blades; one 1mm thick, the other 0.5mm thick, and fortunately both of the same diameter.
Ganged together on the slitting saw arbor, I could slit the head fins with a 1.5mm gap instead of the 1.6mm called for in the plans.  Phil's plans actually calls for slightly thinner fins on the head than on the body, so this is fine; except that I made a slight miscalculation, and instead of keeping the original spacing called for and making the fins slightly thicker, I decreased the spacing to keep the fins to dimensions...  Silly me; that left the bottom fin a bit on the thickish side   :


Next I removed the cylinder from the mill, and flat-lapped the port face using different grades of emery on my glass "surface plate" to get rid of the tooling marks, making very sure that I kept it very flat.  It wasn't a lot of work; just a few strokes each on 320, 600, 800 and finally 1200 emery, and ended up with this:

This is one of the nicest surface finishes I've ever gotten on cast iron; and now I know it is possible to get CI to a near-mirror finish!

On to the piston, and for this, I brought out the best in my minimalist arsenal of tools; my prized Moore & Wright micrometer and Mitutoyo telescopic gauges.  My one sister gave me the M&W many years ago as a gift, and I have never used it much.  The set of telescopic gauges I bought last year in a "Cash Converters" shop for the then equivalent of US$10.  And they are not fakes... Once in a while one gets VERY lucky  ;D.  I'm digressing   
I set the telescopic gauge to the cylinder bore, and used the micrometer to check the reading; three times over to make sure I had no errors, and then another couple of times just to be 100% sure.  I did pick up a slight tightness mid-way along the cylinder bore using the gauge; that's a problem to sort out later:


On to making the piston; I turned the piece of phosphor bronze I have for it down to just over size on the OD, and then drilled and bored the ID to the required size:


Then I finished off the OD of the piston to 0.005 mm (that's a quarter 'thou give-or-take) smaller than the bore of the cylinder as measured earlier - using the micrometer to check.  I have gotten into the habit of working accurate to 0.01mm on my lathe; this was really pushing the envelope for me, so I used my HSS cutting bit as sharp as I have ever been able to hone it, and I was careful to keep a consistent feed while doing the cutting.  I used the compound slide set over to 30 degrees to dial in the final cuts; there's quite a bit of reading material on using this method available.  Then I parted off the piston; the threaded rod in the tailstock chuck is just to keep it from ending up in the swarf heap:

  I'd done well up to now, but forgot one of the most important things I'd learned while making and then parting off pistons    - The parting off raises the metal next to the parting area  - and I didn't pause to clean that up while parting, or even better, do a partial parting before turning the piston to size.

Fortunately I did leave the piston slightly over-size, and would need a mandrel to finish it off together with the cylinder bore.  I left the "left-over" phosphor bronze I used for the piston in the 3-jaw chuck and removed the chuck from the lathe; if needed be I could make another piston from that.  Then I mounted the collet chuck, shoved a bit of 12mm aluminium in it, and turned it down to a light slip-fit for the bore of the piston.  I then used a center drill on the end of it, to allow clearance for the revolving center, and slided the piston over the aluminium, and used the center to nip it up in place.  Then I used a rule with emery to get rid of the high spot on the parted-off side of the piston:


Next I removed the piston, drilled for and tapped an M2 thread into the aluminium arbor, and screwed down the piston on it:

I mixed a couple of drops of thin oil (3-in-one) and some metal polish ("Brasso"), covered the lathe ways with absorbent paper, and coated both the piston and cylinder bore with this mixture.

PLEASE DO USE GOOD SENSE IF YOU TRY TO DO WHAT I DESCRIBE IN THE FOLLOWING SEQUENCES - note I say "good sense" and not "common sense" - last of which is unfortunately worthless nowadays IMHO.  With the lathe running at a low speed (on my Myford I chose back-gear medium speed), I started lapping the cylinder onto the piston using the oil-and-polish mixture - with the cylinder lightly gripped in my right hand and moving it up and down the piston, and my left hand on the lathe clutch to stop the lathe if something went wrong.  Don't try to use just metal polish; it dries out and will tighten up; the oil added to the mixture helps to lubricate it.  And if things tighten up, release your grip on the cylinder first, and then stop the lathe. 

There was not a lot of lapping required, but the tight spot I mentioned earlier in the post while measuring the cylinder was still there (easily felt by a tightness requiring a bit more holding torque when moving the cylinder over that point), so I chose a quick-and-dirty fix for that.
A proper lap would be the best way to go, but I sawed a slot on the mandrel to hold some folded up 800 grit emery trimmed to size to lightly fit the bore of the cylinder when wrapped around the arbor.:


I shoved the cylinder over that, moved it over to where I'd judged the tight spot to be, and started the lathe, once again holding on to the cylinder with my right hand and moving it side-to-side a little bit.  Just a couple of rotations of the lathe to run that tight section in a bit, and I was done with the more dangerous stuff.  A video to break the monotony, and show how the piston fits the cylinder:

OK - End of risky sequences 

Next I started on the wrist-pin bracket.  This one called for aluminium as well - I'd originally set out brass for it, but with the weight of moving parts on this engine playing a major role, I changed my mind and used aluminium.  I have some 5mm aluminium rod scavenged from old UHF TV antennas, but that is horrible stuff to machine, as it is extruded soft ali.  As I have been extravagant on wasting aluminium on this build thus far, some more wouldn't matter anyway, so I flipped the bit of 12mm I already had in the collet chuck from doing the piston to get at the un-machined end, and turned it down:

I just used the step-turning to prevent flexing; though the whole lot could have been done in one go.  The tip is down to the correct size, with some room for machining left on the thicker bit.

The front bit needed to be slit for the connecting rod - and with some more machining in the lathe to come after that, I took the plunge, and unscrewed the lot - chuck-and-all from the lathe, and lightly clamped the collet chuck in the mill vise.  When I built the collet chuck, I left it chunky, so I don't think it will distort from getting used in this rather unconventional way:


Then I slit the ali for accepting the connecting rod - specs show 1.6mm, but I did it at 1.5mm:


And cross-drilled for the wrist (gudgeon) pin:


Back on the lathe again, and I just used the rear parting tool to trim the lot down to length, and with a 2mm diameter back end - to get threaded later:


After final parting off, mounting in the collet chuck to thread the shaft M2 with the tailstock die-holder and a bit of clean-up, the wrist pin bracket was done:

  I was surprised; this is a fairly small part and it came out OK without any hassles!

The valve pushrod followed; nothing difficult; just a bit of 2mm bronze brazing rod - threaded M2 at one end:


And with a flat filed free-hand on the other end for a grub screw (set screw):


One valve push rod done:


With a bit of time left in the shop, I started on the connecting rod - marked out some ali:


Drilled for the big- and small ends:


And milled to size on the accessible sides:


I used a slitting saw to trim it off the parent stock:

When it started to wiggle around - JUST before it was fully parted off, I stopped the mill, and broke it off by hand.  Saves one from having to search for a part tossed across the workshop on final cut-through 
Some filing was required; I could have done more to it on the mill, but setting up sometimes takes more time and energy than a bit of judicious filing:


Connecting rod done; I'm not entirely happy with it as I over-filed some spots (So much for "judicious" filing  ) - but it should do for now:


For anybody that reached reading this point in the post, -    Darn, I admire your persistence, as I was starting to bore myself!

In a nutshell, the results of today's efforts:


I hope to get a bit more done tomorrow   

Regards, Arnold

[Brass_Machine]

...
For anybody that reached reading this point in the post, -    Darn, I admire your persistence, as I was starting to bore myself!

...

I read it all, and quite frankly enjoyed it. Great work!

Eric

[cidrontmg]

...
For anybody that reached reading this point in the post, -    Darn, I admire your persistence, as I was starting to bore myself!
...

I read it all, and quite frankly enjoyed it. Great work!

Eric

+1, and not for a second was I bored! Very enjoyable reading all the way. And lovely work again, as usual. A flame eater is very near the top of my projects list. Watching enthusiastically how it should be done, although IŽll never be able to.

[sbwhart]

Great read and job Arnold 

Thanks for posting.

Stew

[Trion]

Great post Arnold, looking forward to the next one!

[Stilldrillin]

Finally, some more progress 

For anybody that reached reading this point in the post, -    Darn, I admire your persistence, as I was starting to bore myself!


I hope to get a bit more done tomorrow   

Regards, Arnold

Arnold.
Not the least bored. Full of admiration. 

Read every word, and perused every pic. Though, I had to have my breakfast first.... .

Looking forward to today's instalment! 

David D

[shoey51]

very enjoyable read

[madjackghengis]

Hi Arnold,  I finally read your post beginning to end and have a couple of comments which are appropriate.  First off, you are doing a very fine job, both in the machine work, and in the posting, like so many others have said, I'm not a bit bored, I just feel like maybe you should have more friends to present gifts for the improvement and expansion of your "kit".  The one I built is the same size, I made an assumption, having read other builds that were done "by the book" rather than out of the magazine, as I did, and they were twice the size I, and now you, are building.  Mine is essentially identical, except not metrificated.  The plans called for aluminum for the cylinder, and you did very well to ignore that and use iron, I suspect you will have far better an engine for that choice.  I would suggest you look at the thermal expansion factors of cast iron and compare it to the bronze you are using, and multiply the approximately half a thousandth clearance necessary, by the difference, to ensure the piston does not expand beyond that clearance.  In Machinery's Handbook, it lists cast iron at .0000065 unit length expansion per degree, with bronze listed at .00001, making just short of twice the rate of expansion.  I suspect a full thousandth of clearance will give a working clearance of less than half a thou when up to temperature, which is plenty with graphite as lubricant.  If you have any problem with the piston sticking, it could just as well be made of cast iron from the same source, and would not be significantly heavier if you keep the walls thin, as well as the top, of the piston, that is.  I don't believe you will need to use graphite for a piston as the iron won't gall the way aluminum does.  Having read through your post, I'm half tempted to turn an iron cylinder and a piston to go with it, and be done with the aluminum cylinder altogether.  I think you have eliminated all the problem factors I've already been frustrated with over a period of twenty years since I built mine, and since I got it running, only a few short months ago.  I don't wish to impose on your log, but as you, I did not have much in the way of tooling when I built mine, and I used a four jaw chuck instead of the rotary table I didn't have, to turn the cam, and I used Mr. Duclos' numbers, forgetting I was in a different position, and my cam came out with a substantially wrong profile, because I used a radius distance from center, rather than diametral, it seemed to be the same thing at the time, but gave a profile very much wrong, and kept the engine from running, along with other issues.  If you use a four jaw to form the cam, make sure your indicator is showing the full diameter offset, and not just the radial offset, as I did.  I expect you will have a very good running little engine in the very near future, and I'm looking forward to the video, the one with your piston and cylinder is good and shows a very good clearance and fit and should work very well.  I have a cheap tachometer off e-bay, put a tab of reflective tape on the flywheel, and was getting about 2500 rpm easily with fresh pistons and cylinders, and I expect you will get similar results without the galling, just needing cleaning on occasion as the drop of oil for the crankpin will end up in the cylinder.  I am very pleased to see this engine being built again, with differing thoughts, and in my opinion, better materials than I used.  I have seen it built and run with the engine half sized, with a bore of a quarter inch, on u-tube sometime in the recent past, so they will run even smaller, as well as seeing many made in double size, with about an inch bore.  Looking forward to seeing it run soon, great build and fine build log mad jack

[arnoldb]

  Thank you very much Eric!

  Olli.  I'm not sure if this is the way it should be done either; I'm just doing it.  And having seen your Stirlings, you should have no problems at all getting a flame licker going 

Stew, Thanks very much mate

Thanks Trion 

Cheers David D  - I hope you had a full English - nothing like lots of eggs and bacon !

Thanks for checking in you Shoey51!

Thanks Jack - I don't like to call you Mad Jack by the way ;).  There are many members here on MadModder who have helped me a LOT - not through giving me "kit" but through sharing knowledge and supporting me - and that's something all the kit in the world can not make up for.  A load of fancy kit without knowing the basics of how to use it is just that - a load of kit.  I'm striving to use the bits I have, and with the generous help received,  learn to use them well.  Then, as I'm expanding my available bits, I'd just be in a position to use it even better.  Thanks; I did consider the materials I have available for this build - that's why I settled on the CI cylinder.  I'll give the bronze piston a go - if it does not work, then I'll re-do it in cast iron. The influences of heat in an engine is an entirely new experience for me, so I have a lot to learn from it 

I didn't get as much done today; which makes for a shorter post for a change - saves you chaps from eye strain

Following Mr Duclos's instructions I turned a piece of aluminium stock down to the outer and core diameters for the combined crank web/cam:

This was followed by drilling the center 2.9mm and reaming it out to 3mm for a fit on the crankshaft.

Reading through the steps required to machine the cam on the mill and rotary table, it seemed (and was!) a good idea to make up something that I could clamp in the mill chuck for centering purposes.  Seeing as the crank shaft would be ideal, I cut that off from some 3mm music wire I have.  The Dremel and a cutting disc works great for this; the music wire instantly blunts the junior hacksaw blades I have  :


I then centered the rotary table to the mill spindle, clamped up the workpiece in the small Myford milling vise, and used the shaft chucked up in the small drill adapter to center the workpiece-with-vise combination on the RT - with the RT set to 0 degrees.  When I built the RT I took great pains to make sure that the T-slots were exactly on 90 degrees apart and the one on 0 degrees was just that.  So I used the edged square shown in a previous post with the edge located in a T slot to set the vise square, and clamped a bit of flat iron down against the top of the vise to keep the reference Phil mentions in his write-up:


Then I just followed Phil's instructions and dialled in the offset needed on the Y axis, moved the vise against the clamped down reference bar, and used the shaft-in-chuck to locate the final spot to clamp down the vise.  Then milling the cam profile was easy - though I did get the milling depth slightly too deep and ended up scarring the lower workpiece face   :

Fortunately the scar is not as bad as it looks; it's mostly a burr... That 6mm milling bit is getting a bit blunt!

It was easy to set everything back to "0" after milling the cam, and then to dial in the 43 degrees counter clockwise on the RT needed, and then dial in Y to depth to locate, drill and tap the connecting rod screw-hole:


The workpiece was then removed from the RT, and parted off from the parent stock on the lathe.  I wish I'd read the instructions trough to the end again before doing this, as I could have saved myself a lot of work later .  Phil mentions at this stage of his instructions that you have to leave "sufficient" extra stock on the back of the workpiece to later clean up...  So I left 1mm extra and parted off...

A bit of a diversion followed; the parted off workpiece had to be clamped to the RT again to mill out the webs.  I do not yet have a good selection of bits 'n bobs for clamping to the RT; my mill's clamping kit is waaay too big.  The RT's T slots are the same size as my lathe's, and I always just used 6mm cap screws of appropriate length and home-made T nuts to clamp things on the lathe's vertical slide.  I couldn't find a suitable length cap screw today, so I had to use a bit of high-tensile threaded rod.  One thing I did not do in my more inexperienced making of said home-made T nuts, was to prevent anything screwing right through them - as an arbitrary length of threaded rod would do, so a quick-fix was called for.  A chisel, a hammer, a T-nut clamped upside-down in the  big bench vise, four quick blows, and the result:

Now a rod or bolt won't screw through past the end   

I laid out the back of the workpiece, and an odds 'n ends clamping session on the RT followed, using the shaft-in-chuck to make sure the shaft-hole was on center:

No super-accuracy was needed for this step, but parts do look better if accurately made, so I took a bit of time getting it just right.

Then I milled out the web; 6 degrees offset  On the RT for each side, and to the lines:


To drill and tap the web for an M2 set screw, I clamped it in the mill vise, and used a bit of 2mm brazing rod chucked in the small chuck to locate the hole:

There was not enough clearance for a center drill to get in there, so I used the 1.6mm tapping drill to make a little dent to act as starting point. With the mill stopped, lightly press it down on the workpiece, lift of, turn the chuck 180 degrees by hand, press down slightly harder, lift off, turn the chuck 90 degrees, lightly press down again, turn another 180 and press down slightly harder again.  Lift off and start the mill, and drill the hole; the small drill bit will hit the correct spot using this method most of the time without wandering, as the light dent in the workpiece serves as a center mark.
I drilled the 1.6mm threading hole using this method, and then tapped it M2 for a set screw.

Phil notes at this point to chuck up a suitable rod (or turn one down) to 1/8" (3mm in my case) and make a flat on it, and then mount the workpiece on it, locking it down with a set screw through the threaded hole made in the previous step, and to face off the the back of the workpiece to get it to an overall thickness of 1/4" (6.35mm).  I tried that and it was no fun at all...  This is on an interrupted cut with a puny screw trying to hold on...  And remember I left 1mm extra to face off  .  When the workpiece came loose from the shaft the second time, I went to plan B - which was to wrap a bit of paper around the cam, chuck it up in the 4-jaw chuck by the cam; just roughly on center, and face it off to thickness:
.
Had I read the instructions up to this point, I would have parted off to just 0.01mm over size initially, and just removed the toolmarks on a bit of emery; that would have left the workpiece perfectly on size without a lot of additional faffing around.

After a bit of filing to round corners and some work with emery to clean up, I ended up with this:


The crank/cam took quite a while to make, as I expected, so shop time was running out for today.  I did manage to get some additional small bits made though.

The crank pin bushing - 2mm ID, 2.48mm OD and 4.35mm long:


Followed by a 2mm bolt from some 1/8" brazing rod, and a little retaining washer:

I will most likely re-make the bolt from silver steel; it just occurred to me that it will experience quite big forces on it when the engine is running!

At least, things are starting to resemble an engine now :



Regards, Arnold

[Dean W]

Very nice work, Arnold!  The crank/cam is deceptively complicated, and you went right at it, just like a machinist.  : )
I've read all your writing from the beginning, though some days don't have time to post.  This is another fine write-up
with you as the author.   Entertaining and educational.

Something for later, (next time you make T-nuts), if you use an old ball bearing or 60 deg center, you can flatten the bottom
thread in the nuts with a good whack of a hammer.  Works well, and leaves the bottom of the nut smooth.

Dean

[NickG]

Hi Arnold, just found this, not read it yet but posting a quick reply to remind myself and say well done - your work looks great so far, I love these engines. 

Nick