MadModder
Gallery, Projects and General => Project Logs => Topic started by: vtsteam on January 30, 2013, 09:54:55 AM
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I've begun work on a project to convert a Tecumseh H50 5 horsepower horizontal shaft motor to steam. It's been a great learning process for me. The goal of the project was to take one of 3 defunct engines I received in a trade and do the conversion. I didn't want to do just a simple "see it rotate" conversion like many of those shown on Youtube, but wanted to have proper valve events for both inlet and exhaust.
To explain that, many of the conversions I've seen are inlet open for 360 degrees, and exhaust closure is the only thing that provides drive during part of the cycle. The usual procedure for the simpler conversions is to add weld metal to the back side of the exhaust cam lobe and file it to a profile to match the existing lobe.
The camshaft on utility 4 cycle engines rotates at half the rate that their crankshaft turns, and this is accomplished (on my Tecumseh engine) by a set of gears of 30 and 60 teeth with a pitch of 5 TPI. Because single acting steam engines are essentially 2 cycle engines, at least by analogy, the existing cams on a 4 cycle IC engine are rotating at half the rate needed, and in addition, the valve events themselves are quite a bit too long for an efficient running steam engine. In other words the cam lobe lift(s) are too wide.
With suggestions by an experienced steam engineer, my intended valve timing for the steam engine eventually resolved to an inlet opening at 10 deg BTDC and closing at 90 ATDC (100 deg dwell) and exhaust opening at 15 deg BBDC and closing at 15 deg BTDC (180 deg dwell).
Before moving forward with my present plan, I'm going to first retrace here all of the steps (mostly missteps) I've taken so far, including the many mistakes and changes of direction as I gradually discovered problems with my various ideas.
I'm sure this is all old hat to those more experienced in steam and IC engine design, but it may be entertaining for that reason! I'm definitely beyond Plan B -- maybe I'm now at Plan F. But it has been wonderfully educational, particularly with regard to cam design, for me at least, and I enjoy learning this way. It's the old take apart the alarm clock, and try to put it back together before the folks get home kind of approach to education!
Below:
1.) Candidate engines -- all Tecumseh 1 seized, 2 with thrown rods.
2.) The star pupil -- a seized 50H type
3.) Crankshaft and camshaft gears
4.) Camshaft and lifters
5.) The existing IC timing marked off
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My first plan was to cast a new cylinder head, with a boss for a piston intake valve that would be activated by a bash type pin welded to the exhaust valve. This would still require adding a second lobe to the exhaust valve cam location -- opposite the present one. At the time I didn't realize that the exhaust valve cam would be far too wide to work well for this. The old inlet valve was to remain closed, achieved by removing the inlet valve tappet.
I drew out a wooden pattern for the head to be cast in aluminum, tracing around the old head gasket with a magic marker -- the thick marker outline was a simple method for adding a shrink allowance for casting the actual head.
Approximate head bolt locations were marked from the gasket, although these would change due to shrinkage. But they were close enough to give me locations for adding bosses to the casting at the bolt locations. I also drew out the cylinder and valve spaces.
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I carved out a passage in the pattern for the new single inlet/exhaust valve, and added bosses to the pattern for head bolts and a base for the new piston valve and its cylinder -- which would be added as a separate assembly.
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The valve boss was a little tricky to locate and align because the exhaust valve is inclined 5 degrees toward the engine cylinder. I also added a boss for a relief valve over the cylinder center.
Finished pattern below, contrasted with the old IC finned head.
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At about this time I began to realize that a combination exhaust and inlet valve actuation had some limitations. It seemed that the inlet event would have to be symmetrical with the center of the exhaust event. They didn't have to overlap, but a single actuator simply means that those events must be tied in regard to their center points in a cycle. Or at least that's what I thought. This stuff can get tricky to imagine.
I also started to think that a 3/4" thick aluminum casting would absorb a lot of steam heat, at least initially, even if lagged. So I began to think about adopting a suggestion I'd had to fabricate a steel plate head with a bash type ball valve for inlet, actuated by a pin added to the top of the valve, and retaining the old poppet exhaust valve.
This would require adding two new lobes to the cam -- one each for inlet and exhaust. It would also require filling in the carburetor manifold with something (lead was suggested) to reduce the head space left by actuating the inlet valve, but using it only as a pin to actuate then newer ball valve.
Because my sadly rusted used milling machine purchase was in a somewhat exposed storage shed at the time -- surrounded by layers of odds and ends and unwired, and because temps have been in the sub zero (F) here in Vermont lately, I wasn't able to use it at the time. (Happily, I've since got it wired, cleaned, and operational, as well as closing in the shed it is in)
Instead I decided to make the plate head as two laminated pieces, brazed together. This would allow me to make a pocket for the exhaust and inlet valves by drilling the bottom piece -- the other would act as a cover plate.
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Instead of filling in the intake manifold space with lead, I decided to use pot metal (die-cast) -- zinc based alloy from some old auto door handles. It has a little higher melting point than lead, though well below that of the aluminum engine block. It is considerably harder than lead, and it was quite a bit more difficult to file back after the pour. I'd have have poured short, if I'd been a bit smarter about it.
The intake carb seat was simply blocked with wood, and I used a candle sooted piece of 5/16" drill rod (silver steel) to act as a core for the intake valve. In fact I had decided to use this same material as the bash valve lifter, instead of adding a pin to the top of the steam inlet valve.
The valve guide in the engine kept the drill rod at the proper 5 degree inclination toward the cylinder center.
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I originally intended to follow suggestions to weld a standard cast pipe tee to the head as a valve body and use a stainless ball and spring for the valve. A hole in the head itself would work as the valve seat after tapping lightly on the ball to form the seat. But later decided to use a threaded connection to the head -- which would allow some adjustment of the valve assembly height, among other advantages. It would also have been tricky to weld and center the fitting at the 5 degree angle required. Not impossible, of course.
Instead, I turned a separate valve seat out of brass for a press fit (later to be soldered) into a red brass pipe nipple. I used a pipe cap on the end, and silver brazed an inlet connection nipple threaded end into a close fitting hole in the valve body. A spacer at the top of the valve and the pipe cap would allow some adjustment of spring pressure. The valve was therefore a separate assembly that could be threaded into the cylinder head.
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A pattern was made of the head with bolt hole locations by placing a piece of paper over the engine cylinder and tapping it very lightly with a brass hammer -- similar to the old trick for cutting out a paper gasket. This marked the important location details on the paper -- one advantage of a sligthly dirty block -- an automatic grease pencil!
I also punched holes at the head bolt locations with a round pencil -- the tapered point was larger than the hole so it gave a nice locking paper rivet to keep the rest of the paper from moving while I did the rest. A piece of drill rod was also used to locate the center of the 5 degree inclined valve passage.
I now had a pattern for marking out the drill locations for the head bolts and valve.
I marked and cut out the second piece of steel sheet of the head. Most of the steel I used was scrap material.
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I decided to use braze instead of welding for much of this project -- I do own a welder, but need to get more proficient with brazing. It does use a lot of gas however, so I decided this time to try pre-heating the parts. I have a wood stove running this time of year, so why not put the pieces in the coals for a preheat?
I first pinned the two plates together with a couple of 1/8" steel dowel pins. Then popped them into the stove for a bake. The coals away from the vent kept the metal from oxidizing, and when it looked somewhat red, I pulled it out with tongs into a bucket of wood ashes, and trotted down to my brazing site (outdoors, cold) and brazed the part. The ashes definitely retained the heat, and braze was flowing shortly after lighting the torch.
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After brazing the parts together, I used my paper pattern to locate the valve hole, and set the drill press up to drill at 5 degrees. The drill rod and new head lined up perfectly when in position. The head bolt holes matched up.
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After testing the valve location, I enlarged the valve hole and tapped it to 1/2" pipe thread to fit the valve body.
I also chipped out steam passages in the head using a chisel and continued shaping with an electric die grinder. I later polished the grinding marks out and assembled the valve on the head.
Getting close now, I thought. All I need to do is braze a couple lobes on the cam shaft opposite the present ones, and I'm done.
Not.
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So with valve and head pretty much completed it was time to simply add some braze metal to the camshaft, as secondary lobes, file them off to profile and I was good to go.
Just had to figure what that profile was. I marked the cam gear with the existing valve events after turning the crankshaft through 2 revolutions, expecting the timing to be reasonably close to steam timings. I figured it must be in the ballpark because so many people on YouTube and elsewhere have simply duplicated the existing exhaust lobe at 180 degrees, hooked the engine to their shop air compressor and spun up their new steam engine.
But after looking at the timing marks on my gear, I realized things were very different. 4 cycle timing is MUCH broader (naturally) than 2 cycle timing. And those cam lobes were a lot wider than what I needed. To figure the actual dwell for the crankshaft you have to double the dwell you get from the camshaft.
On my engine this meant that the existing cam would open the inlet for about 200 degrees, instead of the desired 100 degree dwell, and the exhaust would be open for about 300 degrees instead of the desired 180. Not only that but the two events would overlap by about 60 degrees. No good.
The photo below shows the measured valve events on the stock cam.
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This seemed to mean I'd have to modify both the old cam lobes and the new ones. Well modify how much? I spent a lot f time sketching out cam lobes, and found a cam coordinate program on the web.
I wanted at least one eighth inch of lift on the inlet cam (for the ball valve) and I wanted about a quarter inch of lift on the exhaust cam for the poppet valve -- roughly the same as it had been on the IC engine. When I tried to sketch this out, or enter it into the program, the inlet cam wouldn't work out unless I made its "base circle" much larger than the original cam. I could not get .125" lift for 100 degrees of dwell on anything smaller than about a 2" diameter base circle. The original cam lobe base circle was 1".
I learned a lot through this exercise. The main reason the base circle had to be so large was that the camshaft was running at half the speed of the crankshaft. And the "mushroom" tappets will bridge any hollow in a cam profile. They will always maintain a tangent to whatever two points they rest on -- in a proper cam they will only rest on one point at any time, but it is possible to design a new cam profile that isn't correct -- in that case, the tappet will "correct" it by ignoring the dip and bridging it.
A small dwell angle like the 100 degrees we need on the inlet of a steam engine (a short cutoff for steam economy) means you need a very big cam to get even a small amount of lift. Particularly on a half speed camshaft.
Anyway, I eventually drew out both an inlet and an exhaust cam that seemed like they might just work, assuming I didn't try to round off much of that profile. Pretty much straight sides to the top of the bump, a sharp angle there and a straight side back down. Not an ideal profile as far as wear goes, or for valve train acceleration. But the best I could do within the constraints of the size of the valve chamber, which I measured carefully. The inlet cam would just fit in. The exhaust cam was somewhat smaller.
So I drew these out as full round cam blanks. I would have to turn off the old cam blanks with the lathe (also rescued from storage) and then braze on the new cam "donuts".
I figured I'd make the exhaust cam bore a little bigger than the inlet cam's so it would slip on the camshaft easier. The camshaft was a solid piece of cast iron, including the cam gear.
Below are drawings of the cam blanks I decided to use. The method of construction was to to turn the blanks to base circle diameter, and then braze on pieces of .125" dia. and .25 dia drill rod. These would set the max lift, and I would fillet them with braze and file to profile. When the file touched both the rod, and the base circle blank, that would be the profile.
(Both show only one lobe for clarity, though each has two. The inlet cam doesn't illustrate the .125 drill rod pin, the exhaust cam does show it and the intended braze fillets)
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The coordinate program I found on the web gave me a bunch of coordinates that looked good as a table, but were totally wrong when I plotted it out. My pin and braze method was the one I chose to make the cams.
I turned down the camshaft lobes, made the cam blanks and bored them, and then brazed the pins in position after carefully marking out. Then I spent an afternoon carefully filing the braze down until I had my new cams.
Below are the cam blanks from scrap 1/2" plate -- interesting patterns on the face from exposure.
And the filed cams ready for mounting on the camshaft. The big one is the inlet cam.
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A chance reference on an internet account of another conversion (the usual weld blob camshaft conversion job) mentioned having to narrow the width of the new cam lobes, because other wise they would interfere with the crankshaft counterweights when they swung up to the cam area.
When I read that I ran out to the work shed even though it was a chilly night, assembled the cams onto the shaft and installed them into the cam space in the engine. Then I rotated the crank.
:doh:
Uh...........no go.
Big time no go.
Not even "trim a little here, slide this over a bit" go.
I mean NO GO. The space for the camshaft in the crankcase was obviously sized to the crankshaft throw. So unless the cams were original diameter, they would interfere.
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So that brings us up to the present
I have a new idea.
:smart:
Uh, external crankshaft mounted eccentric driving a valve in a new head casting.
Well maybe not so new.
Been around for at least a century or two.
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Actually, external valve gear had been my original plan before I started searching around the web for conversions other people had made. The internal camshaft modifications seemed to be the most common, and promised a quick and simple conversion. It certainly would have been nice to package everything inside the engine by modifying a camshaft. And these modifications are certainly do-able, elegant, and probably fun. But they don't result in an efficient steam engine, or one with much power output.
Well I should modify that statement -- if there is clearance for sufficient sized cam lobes on a half speed camshaft, then it would be possible to get good timing figures. But on the Tecumseh, at least, it isn't possible.
My main interest are the Westinghouse style twin engines, like the Stuart Turner Sun and Sirius, and other model boat engines built in the early history of model steam boat racing. I own two antique model Westinghouse style engines, and once started construction on a new one.
Westinghouse twins almost always have external valve gear (though there are exceptions) and something similar to this for valve actuation was what I had originally imagined for the Tecumseh single conversion. That conversion was intended to give me practice and performance figures for a subsequent scratch built Westinghouse style twin.
Well, now it's back to that original idea, external valve gear and a head casting to receive the valve.
My plan now is to try a shaft type rocking valve coupled to an eccentric on the crankshaft. This seems to me to give a very simple linkage, allowing me to use pressure to keep the valve faces steam tight, as well as compensate for wear, while reducing wear over a full rotary valve.
A piston valve could also be used, but these must be very well fitted, and it seems to me that any wear, no matter how well fitted originally, would lead to steam leaks.
Traditionally, a D-valve was used on top of the head, with a linkage composed of either bevel gears and a vertical crank shaft, or a long bell crank and a ball end somewhere in the linkage to take up side motion.
I think my choice is the simplest I can think of for linkage, and offers some of the advantages of all of the other valve types.
So, on with the show......
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I had a little time today to work on the head pattern. Here it is being tried on top of the cylinder.
(http://i786.photobucket.com/albums/yy150/vtsr/NewHead.jpg)
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Looking good, not 100% sure what your up to yet but judging by the bosses in the side of the head it should be interesting.
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Hi David. The bosses on the side of the head will form the valve housing. The bosses will be bored through the head to fit the valve.
The valve itself will be a shaft which rocks, driven by the eccentric on the crankshaft directly below those bosses. A pushrod will connect the eccentric and a horn on the valve shaft.
The shaft will have milled areas to pass steam to and from the cylinder head beneath.
The long oval boss on top of the head will be drilled and tapped for a steam inlet pipe and an exhaust pipe.
Two ports directly under these, below the valve body, will be the steam in and exhaust ports.
It's all very simple.
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sounds like you have your project figured out more than I have mine. Im stuck looking at some scribble on paper atm. Ill sleep on it and hopefully dream up some solutions...
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I'm sure you'll work it out David.
I painted the head pattern this morning. Getting close to the point where I can cast some metal.
I pulled out my old core boxes today, and will likely bake a 1/2" dia. rod core. My wife is planning on baking some chocolate chip cookies, so I'll put it in the oven with them. I use molasses water, so the cores smell good while baking -- makes it easy!
(http://i786.photobucket.com/albums/yy150/vtsr/vtsr/TecumsehBuild/NewHead2.jpg)
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Hi
Pattern is looking good.
Hope you get a good cast Cheers David
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Thanks, Meldonmech! :nrocks:
Here's the baked sand core. Cookies were good too! :thumbup:
(http://i786.photobucket.com/albums/yy150/vtsr/vtsr/TecumsehBuild/BakedCore.jpg)
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Head pattern is looking good. Interested to see how it looks.
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There's a familiar sounding name! I'm staggered by your workmanship b85v. :bow:
I sent for new piston rings, gaskets and oil seals -- guess that shows some confidence that there may be an end in sight for this project. I'd like to build a new steam engine from the ground up next time.
My shop facilities get closer to reasonably usable every day. A working mill and lathe, now, though they could use some more work to get them in good shape. The foundry is ready to do its first real pour. Up to this point it's been mostly rough work with torch grinder and files and brazing. And mostly without heat. But with real tools I hope to do better.
I think I'm going to enjoy making the eccentric for this one. The rocking valve will be interesting, too. Well so will casting again. Feel like I'm on the verge of the good stuff. And the days are getting longer again.
Hope to see your work!
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when do you think you will be casting?? I see bv85 found you, and you dropped the other forum... I planed on doing that as well, too much uncertainity with its longjevity. hmm no spell check..damn... oh well, they have better smileys here :clap:
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I hope to cast this coming week David. I will have to get my greensand back in condition, and wait for good weather, so not definite yet.
I'm thinking I need to make that long oval boss deeper and wider to accept bigger exhaust pipe. It's okay for the inlet, but I'd like more diameter for exhaust.
This one will be aluminum just for a trial run, and when the weather warms I'll do another one in CI. which will be the permanent one.
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There's a familiar sounding name! I'm staggered by your workmanship b85v. :bow:
Hope to see your work!
Well I keep trying to improve and do the best I can. I think this forum will be a good fit for your project. I don't post here a lot but check in pretty often to see what projects are going on.
My engine build is over at www.modelenginemaker.com. There are a number of us active on both boards.
Glad you found a place to post your project so I can keep up with it.
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I certainly want to keep up with your as well!
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In between cutting and splitting wood, and putting the scraper blade on the tractor today in preparation for a big storm, I managed to cast the new head in aluminum.
It was great to use greensand methods again -- although I couldn't use my fine facing sand, as it was frozen solid. But I did have my regular molding sand in condition after working on it for a few days. Kept it in a plastic box indoors. And rammed up the mold on the dining room table while my wife was out :ddb:
I'd already started the charcoal in the new furnace, and I had the pour done in a half hour, start to finish. Cleaned up the mess, ran outside and split more wood with an innocent look on just as she got home. She did figure it out though. Missed a little bit of sand..... :wack:
Great to finally have a part to work with now!
(http://i786.photobucket.com/albums/yy150/vtsr/vtsr/TecumsehBuild/HeadCasting.jpg)
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Looks good. Now you'll have something to work on while your snowed in.
:clap:
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That's why I rammed it up ASAP on the dining room table!
I'm not as dumb as I look.
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I was wondering.
As this is a vertical engine, how are you going to get the condensation out ?
Dave.
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Hello Dave, if you mean for starting, there will be a stopcock in the head as usual on a non D-valve engine since the steam valve can't lift off of its seat.Or do you mean steam migrating past the rings into the crankcase?
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I meant for starting. Looks as if you have it covered.
Dave.
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Thanks Dave, but you got me thinking. If instead of a stopcock it was a spring loaded pressure relief valve plumbed back into the steam outlet pipe, it would be automatic. I wonder if that would be better? I guess the stopcock might be better. Water locking on startup isn't the only reason you might want blow off steam.
I've also thought about condensation in the crankcase. Maybe the steam line could run through the oil and the oil temp kept above 100C. Crankcase would best be lagged as well as the cylinder, then, I suppose.
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Snow is coming down and I'll have to start plowing shortly. But got the underside of the head milled and the bosses milled on top.
(http://i786.photobucket.com/albums/yy150/vtsr/vtsr/TecumsehBuild/HeadCastingMilled.jpg)
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Snow Blah!! would rather roll in a pile of stainless swarf...
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11 to 19 inches predicted here, winds to 33 mph, wind chill -4F. And most of it at night, which means it will be drifted higher than the scraper blade by morning, and that makes it tough going.
Guess I'll plow at dusk and let it go over night, see what the morning brings. We're lucky I guess -- somewhat north of the main track and force of the storm. I hear Boston is going to get hit big time. Well, plenty of wood stacked up, and the 6 hp Lister Diesel generator is ready to go. Probably won't be able to get in the shed for awhile, so no machining. Maybe filing is all I'll do. And think about how to do the valve.
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Vtsteam,
Water in the crankcase could be a real problem. don't most vertical steam engines have the cylinders and crank assembly separated ?
Dave.
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Dave, the Westinghouse twin types didn't, and most racing model hydroplane singles don't.
So I will be curious to see what happens with this one, and also what I can do about it if it does become a problem. I think of this as a development project and a way of getting hands-on steam engine design experience.I always like trying things out for myself. Plus it's fun. Plus it gets rid of one more junk engine by making something interesting out of it.
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Vtsteam,
Water in the crankcase could be a real problem. don't most vertical steam engines have the cylinders and crank assembly separated ?
Dave.
Water in the crank case has been a problem on this sort of design.....My concern is the oil ring, there is holes in it and the piston. I was thinking maybe replace the oil ring with an O ring or maybe a lip seal??
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That sounds like a good idea. I did order new rings, and they've arrived, but I haven't put them on yet. Maybe I should try it stock first just to see how bad it is...
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it probably wont be to bad with a bit of super heat once you get the block temp up. there was an interesting write up on this a few months back in the steam automobile club of America's publication "the bulletin" .
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I saw Bart Smaalders comment also re. his otter engine conversion:
The instructions for the Westinghouse engines (twin cylinder single acting like Otter) was to fill the crankcase with water and add some steam cylinder oil; this just worked really well for me and kept oil carry over down.
I just happen to have some steam oil -- bought a bottle of it at a small engine meet in Bernardston, MA a few years ago, and I've been looking at it on the shelf ever since!
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hmm, not so sure about filling the crankcase with water, just sounds like a bad idea :loco: You will probably never keep all the condensate out of the crank case, just do your best to minimize it. Then again you could make a double acting cylinder and mount it to the deck of your block and use the existing piston as a cross head....But that probably isnt what you really want to accomplish on this project....
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I don't know, David, Bart Smaalders has many years experience with his compressor conversion steam engine in his boat. If he says he ran it that way and it worked well, I believe him. On the other hand, simplest is best, and I'll just try it with conventional oil filled crankcase first. I don't think it would be a problem to run some copper steam line through the sump. With the head stopcock open I bet the engine, including the oil will warm up in a reasonable time, if lagged well.
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who is bart and do you have a link to his work? It may work, but what about other problems once the engine is shut down? like things rusting up? Im not knocking what he is doing, but keeping as much condensate out of the crankcase as possible seems like a better idea to me.... I would like to read up some more on what he is doing though.
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WO WAIT A MINUTE!!!! what if you filled the crankcase with a bit of antifreeze and oil?? the anti corrosion properties of the antifreeze would keep things from rusting and its also a mild lubricant and it could give a **** less if blended with a bit of water....
Hmm now thats interesting...
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Just found this link David -- pretty interesting. I'll also get the Smaalders links. Back in a bit.
http://books.google.com/books?id=PbxBAAAAYAAJ&pg=PA16&lpg=PA16
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now im thinking about airation and emulsifation...maybe skip the oil all together and replace it with graphite in the antifreeze???
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Here are some links for Bart Smaalders and water in cranckase:
http://steamautomobile.com/phorum5214/read.php?1,20715,20715
His boat, engine, boiler with additional links:
http://smaalders.net/barts/boat.html
I believe he has used that engine on Otter since at least 1996.
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I'm not going to go too far afield with this project. Oil is the lubricant, and if I can use it in the usual way, there won't be water or other substitutes in the sump. I think if I can bring th oil above 100C that condensation won't be a problem in the sump. If that doesn't work, then I may try the oil in water route. But I'll leave the antifreeze and graphite mix to you David! :beer:
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LOL yea im kinda grasping at straws, but sometime you have to say what you think to see what the reaction is....boy I bet the guys on the saca forum are going to have a ball with my last post....LOL :headbang:
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I'm following this build with great interest. But I am having a bit of a problem with the basic concept. I am not a steam man by nature, even if I am building a steam loco. But I have spent about half of my working life as a mechanic on internal combustion engines.
My problem is what I can't envisage how you will start a single cylinder, single action (steam only on one side of the piston) if the engine is in the bottom-dead-centre position. Or ,say, half way up on the exhaust stroke.
Do you have to initially turn it by hand ?
I can easily see how a twin will start. Or a single cylinder double action. But not a single.
My apologies for appearing so thick.
Dave.
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Hey DavidA,
I appreciate your questions so fire away!
It's true you can' just start from a stand still with a steam single if it is in the wrong position. You would have to rotate it a maximum of 180 degrees. You can do so at any speed, as long as you get there.
Not so with an IC gas engine. It needs to be turned over a maximum of 540 degrees under ideal condiitons, and at a speed fast enough to induct the fuel and air in the right mix and strike a spark, assuming it has a magneto. If fuel is not right at the jet in the right mixture, it will need to be turned over until that occurs. Also the mixture will need to be correct for the conditions of temperature and pressure. Hence the need for a choke, automatic, or manual, or fuel injection, often accompanied by a computer and associated programming.
I'm going to have to go outside shortly and start my snowblower. I'm sure that the above process will be demonstrated a few times over! :bang: :lol:
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Actually I didn't completely answer your question. Which was, does it have to be started by hand? You can start it by hand using the pull starter, or a crank, or take advantage of the ring gear on the flywheel and add a starter motor. Just like an IC engine. You could also rig something up clever to make the engine stop at he correct position for re-starting directly by steam.
I think this question comes up a lot because so many steam vehicles, cars and locos, did not use a clutch or transmission -- things that became commonplace after the IC engine came into favor because of its greater difficulty in starting, and its poor low speed torque curve.
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Thanks for that. It is reassuring to me in that wasn't barking up the wrong tree.
Dave.
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DavidF, new ideas and experiments are important. And I don't think anyone is laughing at different ideas. We all work on estimation and experience, but those can be altered by experiment if results show them to be incomplete.
I'm taking a pretty conservative path with this engine -- backwards almost -- with an eccentric and external valve gear. But when finished it will be a nice baseline to try a few ideas out on. And it will probably bring up problems to solve. Which is a good thing.
BTW, cast iron naturally has graphite in its makeup, and I plan to make a new CI head when the weather warms. Not that I expect the valve to run dry, but CI will run better than aluminum I believe.
I think antifreeze in the sump would be a problem because it would need to be drained fairly frequently and replaced as it got contaminated or diluted in a steam crankcase. It's expensive stuff, and environmentally problematic. Not saying it is impossible to maybe work some of the problems out. But it wouldn't be my first choice. Obviously auto water pumps work fine in that medium, so other mechanisms are feasible with it.
The old water and oil crankcase mix seems to depend on the oil separating readily from the water and floating on top, so the two can be drained separately if necessary. Easy to get rid of the excess water due to condensation with a bottom drain plug, while maintaining the lubricating oil in the sump.
The oils recommended for this are heavy weight and very specific -- not your usual automotive multigrade high detergent motor oil, which would quickly look like a milkshake emulsion if mixed with water in a crankcase.
So, I think the fact that antifreeze an graphite would combine with water, might be the actual problem, separation and layering seems to have an advantage.
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But if you used the straight antifreeze not the 50/50 mix stuff then it getting diluted by the condensate wouldnt really be a big deal.
I would have to experiment some to get a better understanding of how the heavy steam oils work with a flooded crankcase. But thats for a later time, getting ready to start carving out a pattern for my enclosed twin build, then its time to melt some Iron again :D
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I was thinking about the cooling fins on the barrel. As the idea would be to retain heat, not get rid of it as with a petrol engine, would it help to fill the gaps between the fins ?
Dave.
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I was thinking about the cooling fins on the barrel. As the idea would be to retain heat, not get rid of it as with a petrol engine, would it help to fill the gaps between the fins ?
Dave.
Yes it's been suggested before that rope type insulation between the fins would work as lagging. I might prefer to reduce their number as well. They do add stiffness to the cylinder -- the walls over the liner are relatively thin so I wouldn't take them all out. We'll see when I get to finishing details.
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So I was drilling the head casting for the head bolts after marking out their locations and the location of the valve bore. Got 3 of them done and ran out of kerosene in my oilcan which I usually use on aluminum when drilling. Thought I'd just finish step drilling this first 3/32" pilot hole when ...snap! You guessed it, and I knew it, should never have done it. I knew better. :bang:
Broken drill in 1" of cast aluminum. Tiny one, too. Nothing to grab onto and try to reverse twist out.
So I brought it inside and tried to recall all of the tricks people use to get the drill out.
It was in a boss so I heated that and tapped the head upside down -- maybe I could expand the hole with heat and it will just fall out.
No such luck.
Then I sat down for awhile and thought about drilling up from the bottom of the head to meet the broken piece, and then tap it out with a drift. Well maybe that would work, but tomorrow, as it was getting too dark to work in the shed.
Finally I wondered if I could get it out with a magnet. I have some really powerful magnets from a big old hard drive. So I found those -- I have two -- and pulled them apart -- which took considerable grunt. I rubbed one over the hole, and all of a sudden, chunks of drill bit came out! I probed around in the hole with the point of one of my daughter's school compasses -- the cheap pencil type, and I could still feel steel embedded down there. Then I realized I could stick the magnet on the compass, and it would become a magnetic probe. So I did that and scratched around in the bottom of the hole, and pulled out more bits and pieces. After about 15 minutes of this, I felt aluminum at the bottom of the hole! :ddb:
Well, I don't know if that method has been written up before, but it worked at least once for me, so thought I'd pass it along!
I'll be filling the oil can back up with kero tomorrow.
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:clap: :clap: :clap: :clap: :clap: :clap: :clap: :clap: :clap: :clap:
What a good feeling that must be! - thanks for posting that
Dave
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Hi just a shot in the dark but if you ran some steamlines through your oil would you have enough heat to evaporate the emusified water that could be vented out of the engine? I would think steam could create steam lol.
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Tom, that's actually the plan A if there is a problem with condensation in the crankcase! :zap:
Thanks DMIOM!! :wave:
Today's tasks:
I completed drilling the head bolt holes, and they all line up. I must ]have removed all of the old pilot drill bit, because that hole drilled fine -- I did leave it until last, though.
Then I thought about drilling the valve bore. This is a tricky one since it is 6" long and should finish out to 1/2" in diameter. It goes straight through the casting from one boss to the other.
Having just recommended to someone else on the forum that they drill a long hole by coming in from both sides, before boring to final ID, I figured I'd better take my own medicine and do it that way, too.
My 1/4" drill bit was barely 3" long, and I planned to start with that. Since I'm also doing a thread about my Gingery lathe and the use of faceplate and angle plates to do a lot of work, I decided to do the same thing here to drill the hole. I have a Sears/Atlas 12"x36" lathe now that is somewhat accessible in an unheated storage shed. The Gingery lathe is packed away.
I used some of my Gingery lathe angle plates to set up the drilling operation on the Atlas, just as I would have in the past. The head casting was bolted to one angle plate, and a reference line squared to that. Then the angle plate was bolted to the faceplate (off the lathe and in my much warmer home). Then a short trip to the brisk machine shop atmosphere of the shed carrying the faceplate setup. Metal sure gets cold fast!
Once the faceplate was mounted, I brought the tailstock up to the casting with the dead center in place, loosened the angle plate/faceplate bolt slightly and tapped with a soft hammer until the casting drill mark was just touching the point of the dead center. I already knew the casting valve center line was square to the faceplate. I just tightened the angle plate bolt, and was good to go.
I had also mounted a second angle plate to the face plate as a balance weight. I engaged the back gears and set the belts to a speed of about 60 rpm. I first checked that I had clearance all around by swinging the lathe by hand before switching on, and also did a last check of the squareness of the valve centerline with the faceplate. To start the hole I faced the boss, center drilled it, then mounted the 1/4" drill bit for the first hole. Everything went well, and I made sure to clear the drill frequently.
After I drilled right up to the end of the flutes on the 1/4" drill, I switched to a 3/8" drill to open it out more. This went quickly.
Then I unbolted the casting, turned it around, remounted it as before, and drilled from the other side.
(http://i786.photobucket.com/albums/yy150/vtsr/HeadCastingDrillingValve.jpg)
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The result? The holes lined up almost perfectly. I couldn't even feel a ridge with a piece of drill rod I sent down there. :ddb: :ddb:
I unscrewed the faceplate and brought it into the warm house to think about my next move. The holes lined up so well, I'm even thinking of welding an extension onto a 1/2" drill and sending it all the way through, rather than boring. Then either reaming or lapping that. It might come out a little oversized, but I can turn the valve body to suit. Otherwise it will be tough to bore out a a small hole like this one (3/8" x 6" starting) -- since it will require a very small, and therefore flexible boring tool. I could do it, but it will be very slow going.
Anyway, looking at it and thinking about it.
(http://i786.photobucket.com/albums/yy150/vtsr/HeadCastingDrillingValve2.jpg)
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My advice would be drill it another 64th then decide.
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You know, after thinking for a minute, you don't really need a seal across the whole 6". Just where it counts, like maybe the length of the drill bit???
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Thanks David for your ideas. I guess I do want bearing support near the ends and want a true bore all the way. I can't count on the fact that the holes seem to have met up well. It needs to be a true hole.
I read up on D bits in Hasluck -- the old style machinist's handbook. I've also made stationary boring bar bits out of 1/4" drill rod in the past -pseudo D bits, by flattening the end, hardening and tempering and grinding. But these are fairly flexible for even a 4" cut, and cut slowly.
After thinking about it for awhile and looking at a wood spade drill bit, I think I'm going to modify one of those into a boring bit. They are a little shy of 6" total length if you grind off the end spike, so I'll add to the other end -- it doesn't have to be tool steel there.
Probably I will end drill a piece of 3/8" square keystock and braze the spade bit end into the keystock to lengthen it. That square stock should fit in my lathe tool holder and provide good stiffness and support.
I'll turn the corners of the keystock round near the bit shank so part of the keystock can enter the drilled hole.
For the bit material I'll maybe use a 3/8" spade bit -- convenient for this size. It will be ground to a boring profile -- the back side of the flat will be ground away so it doesn't contact the hole sidewall. A cutting tooth will be ground on the contact side. Interestingly, the clearances of the end and side are already correct, so I can leave those.
I think spade bits will work well because they are a lot stiffer than the drill rod boring bits I've made -- I measured the shank of one I have in front of me now and it is .28" -- a little heavier than 1/4". And it must be hardened in a way to give it some extra rigidity, by comparison.
So basically I will be boring the hole to size, not drilling. I'll just be modifying a wood drill bit to do it.
Pictures tomorrow when I make it. Fingers crossed it will work out......
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you can get some pretty long masonary bits as well, plus they are carbide tipped :clap:
I have some concerns about boring 6 inches with the tool only supported on one end. Were you going to bore then ream to final size?
Maybe you should make a trial run in something to test it out???
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A likely looking boring bar! I believe I found this one on the side of the road a couple years ago. Not a 3/8" but you get what you pay for, I guess.
(http://i786.photobucket.com/albums/yy150/vtsr/ImplementDestructo.jpg)
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A little cleanup and marking out what I want to grind off.
(http://i786.photobucket.com/albums/yy150/vtsr/vtsr/TecumsehBuild/ImplementDestructo2.jpg)
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Finished implement of destruction -- drill bit brazed to a piece of key stock. Not pretty, but effective.
I drilled the hole out to 15/32" and 5 passes with the new "boring bar" got me to 1/1000th undersize. I didn't do the final pass because I was well frozen by then. It takes about 20 minutes per pass at the slow speed I'm turning the faceplate, and light cuts I was taking. Standing there in 35 degree temps watching the lathe go around eventually lost its charm and I headed up to the house to warm up and eat dinner.
But progress!!!! :ddb:
(http://i786.photobucket.com/albums/yy150/vtsr/vtsr/TecumsehBuild/ImplementDestructo3.jpg)
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Hi vtsteam , a very interesting project , nice work and nice posting too , thanks for showing .
Cheers Mick
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VTsteam, you must be a happy guy right about now. Boring deep holes like that is a tough feat to do well. So what's next? Or are you going to make us wait for the next installment?
:hammer:
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Valve calculations! :hammer: :hammer:
(http://i786.photobucket.com/albums/yy150/vtsr/vtsr/TecumsehBuild/Valvacalcs.png)
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Thank you Micktoon! :beer:
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BTW, I'm very much liking that spade bit steel. It remained absolutely sharp after 2 hours of boring and light cuts, too, which in a sand casting can be rather dulling. The spade bit was hardened full length, too -- when I tried to file the base end, I couldn't.
Considering the cost of tool steel these days a wide spade bit might come in handy for making other tools. I'll have to think about this.
I also think I'll re-do the brazing and clean this one up to be a little more presentable when I'm done with it on this hole -- it's definitely a keeper boring bar. If I choked up on it (baseball bat expression) and the overhang was say 4" instead of 6" it could probably have taken a .010 cut fairly easily and it can fit in a 3/8" hole -- which is tough to do for a bar of any length.
Another nice thing about using a spade bit here was how easy it was compared to the ones I've made out of drill rod. For those I had to heat to cherry, forge a hook in the end, plunge, re-heat and temper, and then grind to shape.
For the spade bit version, all I had to do was grind it to shape -- the other steps had already been done. Plus a top rake cut was already built into the drill bit. I just ground the end of at slightly less than 90 degrees and very slightly radiused the cutting corner, allowing about 3 degrees of clearance under, and carrying that around the radiused end.
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Reamed the valve space to .001" oversize and checked the fit with a piece of 1/2" drill rod.
Then I drilled .375" upper valve orifices, and then faced down to an eighth above that at 9/16" diameter with an end mill.
Then I blind tapped the holes for 3/8" NPT pipe. The valve body is properly centered under the inlet and outlet bores. Everything looks good.
Next step is make the valve.
(http://i786.photobucket.com/albums/yy150/vtsr/vtsr/TecumsehBuild/Headtapped.jpg)
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After many days of thinking about and drawing out valve diagrams, I have come to realize that I can't do what I want with a rocking valve. The only possibility at this stage, using the head I built is to go with a full rotary valve. And after much consideration of the way to drive that, I've also had to discard the idea of an eccentric, because I'd need at least two eccentrics and connecting rods to make a full rotary valve work.
The only way to achieve what I want is either add a timing belt or chain drive. I've settled on a timing belt because of the reduced need for lubrication of valve gear. Not my original preference. I really looked forward to making the eccentric gear. It would certainly look better running. But I do want this to be a practical engine, and the focus of this project was to produce a steam conversion with efficient valve timing -- in fact to be able to experiment with efficient valve timing.
So, I've ordered some timing pulleys -- I may yet make my own after they arrive -- once I have them I can easily copy the tooth profile onto a cutter for that size pulley.
I'll wait on ordering the belt to see what the true distance is after adding the pulleys and a head gasket and bolting the head down.
I'm still working on the actual valve rod configuration, as all my original work is now wrong. Still, I've learned a great deal about valve mechanism and timing -- I think I understand some important underlying principles of valve drives in general now, and shouldn't have trouble designing them in the future.
Here's the engine as it stands now, awaiting delivery of the timing pulleys. And a picture of it back when it was a seized block.
(http://i786.photobucket.com/albums/yy150/vtsr/vtsr/TecumsehBuild/TecumsahBuildUp.jpg)
(http://i786.photobucket.com/albums/yy150/vtsr/Tecumsahstripped.jpg)
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I got to thinking, couldn't you just mill slots thru the valve for the ports? Kinda like cutting a keyway groove except that it goes all the way thru the shaft and have two slots so many degrees apart. One for admission and one for exhaust. That's provided you didn't drill all the way thru the head yet because you would have to slot those passages as well...
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David, do you mean in a rotary or oscillating valve?
Slots in a rotary valve will give you two openings per revolution.
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Occilating. So you can drive it from an eccentric.
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You can't get the valve timing I want from an oscillating valve. Hard to explain. I've worked my way through this with many drawings, and finally grasp it as a principle. The same thing happens with a conventional slide valve. The midpoints of the openings must be 180 degrees apart for a single slide valve or oscillating valve. I want an asymmetric opening sequence.
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I have been wondering what would happen if you used a belt drive and a coupling rod - the belt to maintain drive in the right direction and the coupling rod to keep timing accuracy. It wouldn't be very elegant - but I can't help wondering.
Russell
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Russel, I'm certain that would work, as well. And where new cogged pulleys and belts weren't available, and there was a need to link two wheels, it's one more possibility.
In a sense that is what is happening with wheels running on a surface tied with a rod -- the surface enforces direction. I don't know very much about locomotives, and so maybe an 0-4-0 has the rods out of phase on opposite sides of the driven wheels, as well as the tracks to enforce direction. Railroad modelers will certainly know the answer to that, and I would like to hear about it.
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Just to give an update on progress, the cogged pulleys have arrived, and I've bored them out to fit the valve and crank shafts.
I've measured the belt length after checking with the head and head gasket installed. I hope I got that right so I don't have to use an idler. :zap:
I ordered the belt I think will work and it should be here in a few days.
I changed the valve design yet one more time :wack:, and so had to plug the ports I had already drilled. This head is definitely just a practice head!
I've re-drilled the ports, and am now filing them to a profile I think will work by hand. I haven't shaped the valve spindle itself yet, but that would be the next step. I'm a bit nervous about making a mistake doing that -- it would be very easy to get them 180 or even 90 degrees out of phase, or in reverse positions -- I'm having more trouble with orientation puzzles these days than I did 20 years ago! :bang:
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Milled the valve body today. As predicted I made one orientation mistake, but managed to save the piece as I'd left the stock extra long, and simply reversed it.
Still waiting on the belt. :coffee:
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I've been working on this project without posting anything, probably because I didn't have anything positive to post. But that's silly, you can't always post the good stuff. So here's the present state of this conversion.
I received the timing pulleys and belt and made up the valve spindle. I replaced the old piston rings with new ones, lightly honed the cylinder bore, replaced all gaskets and shaft seals with new ones, replaced the old head bolts with shorter Grade 5 bolts to suit the new head height. I blocked off the old poppet valve recesses in the head, and assembled the head and mounted it on the engine. I also mounted the old flywheel.
I gave the engine a try on compressed air, from 10 psi up to 100 psi pressure in steps. It wasn't a runner. The cylinder would move to BDC and stop. It was obvious that there was leakage between the inlet and exhaust ports.
I discovered that there was porosity in the casting along the valve spindle. This would mean scrapping the head and re-casting, as there wasn't enough metal to put a sleeve in.
After thinking about it for a short time, I decided to try using a sealant in the spindle bore as a temporary measure for running on compressed air, just to get the engine moving. So I swabbed out the interior with high-temp metal filled epoxy, let it cure and drilled and reamed again. I knew this wasn't likely to work for long, if at all, but though it was worth a try before scrapping the head. I can't pour metal now because of the winter build-up of snow and ice outdoors where my foundry is. So a new head will have to wait.
The sealed head was definitely better, but the leakage problem was still clearly audible. It may be that the swabbing and filling was incomplete. The engine did reactmore quickly, but still stopped just past BDC. I did try adjustments to the timing by altering the timing pulley positions, but never got past rotation to BDC.
The inlet and exhaust ports through the head into the cylinder are not joined on my design, and I thought that some of the leakage might be traveling axially on the valve spindle. So I added four O-rings to the valve to seal the valve areas from each other. This made a big difference in the amount of leakage. But still the engine could not get much past BDC. The rotation was much more lively, but not enough carry through. I don't think I can get any better without making a new head and valve assembly.
Probable and possible issues:
1.) remaining porosity and rough bore
2.) oversized bore
3.) cold temperatures increasing the clearance of aluminum housing and steel valve (testing in winter with compressed air vs live steam)
4.) flywheel too small
5.) lack of run-in time, high engine internal friction.
6.) valve timing -- cutoff too short (inlet @ 10 BTDC, cutoff @ 90deg ATDC) - more appropriate for steam running than compressed air on this engine
7.) cross port leakage is still present -- audible inlet flow even after BDC if the crank is held stationary. I don't know if this is flow into the cylinder or along the valve. Probably the former, now that O-rings are installed
Anyway, there it is. I'm not giving up. But I definitely need a new cylinder head and valve design. I'd still like to do it with a rotary valve, but the first attempt was pretty much a stab in the dark.
Here's the engine assembled.
(http://i786.photobucket.com/albums/yy150/vtsr/vtsr/TecumsehBuild/TecumsehWSteamHead2.jpg)
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Hi,
Plan B can't be far away, it just might not be visible yet! You also gave us some really interesting stuff to read about Ralph Watson and his amazing work. I'm looking forward to the next phase of this conversion! The snow'l melt soon and so will the Al!
Regards, Matthew
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I reckon a heavier flywheel would help push it past TDC. Just a thought
Pete
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Thanks greatly Matthew for the boost! :nrocks:
I've got some Plan B ideas for a rotary valve now that I will try. I'm already modifying the head pattern to cast again as soon as possible.
But I also realized that if I made a bolt-on valve housing as a separate piece -- I could work on a valve configuration (from the solid) now, and test it before I recast the head when the weather cooperates. Then just bolt them together.
A generic head with a simple base boss (say that fast!) and tapped for a bolt-on valve housing can be re-used for many different valve configuration experiments, if need be
Pete, I think you are right -- it might work with a heavier flywheel (and some loosening up by running in for a period).
But I really want the valve to be leak free first. And it leaks some into the cylinder while stationary with the inlet valve closed. That's no good. So I need to make a better valve. Thanks for replying! :beer:
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I finally got a chance too peruse this thread.
Wow. You really do some fantastic work. :headbang: :headbang:
Some of this stuff is beyond me for the moment, but I am enjoying taking the plunge with you.
Eric
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Thanks Eric!! :mmr:
You guys' interest keeps me going and not discouraged. :beer: :beer: :beer:
Last night I reconfigured my cylinder head pattern, below. I made a pretty big flat boss -- probably don't need it that big, but it will give room for trying different things.
I'm hoping to be able to work on a prototype rotary valve idea I have today, too. Maybe even just mock it up in materials at hand. I suppose I could test something like that even off of the engine and head. The main thing is to see if it seals well and how much friction it has.
(http://i786.photobucket.com/albums/yy150/vtsr/vtsr/TecumsehBuild/TecumsehPatternHead3.jpg)
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Well, I got tired of waiting for bare ground and went ahead and cast a few parts right in the middle off a couple feet of snow. Not something I'd want to do regularly, but the castings came out okay. Below is the new head casting, just broken out of the sand and still attached to the sprue.
Feels good to be able to start work on this project again.
(http://i786.photobucket.com/albums/yy150/vtsr/vtsr/TecumsehBuild/NewHead2cast.jpg)
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VT
Be carefull you don't scratch that table or SWMBO may have you living in that snowbank hugging the furnace to keep warm. :lol: :lol:
Looks like a lovely job of casting though. Glad it was a sucess. It should be Maple Syrup time pretty soon. Maybe you can boil a pot of that on the furnace while casting, don't want all that heat to go to waste. :D :)
Cheers :beer:
Don
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Thanks Don,
Amazingly enough SWMBO allowed me to ram up the mold on the dining room table! As well as break out the casting! :bow: :bow:
I asked, but figured I'd get a negatory. But she said okay. Guess she knew I'd been waiting weeks for the snow to clear, and took pity after last week's blizzard.
Maples have been tapped for a couple of weeks already, and the local Grange annual Sugar on Snow Supper was in February. I volunteered as a waiter. Funny, I've never boiled sap, myself -- maybe just because there is so many doing it. We get it free for helping a farmer collect sap. But maybe next year with my daughter we should boil up a quart or two of syrup, just to have done it.
Can't do it with foundry heat though -- too short a burn. The local sugar houses run overnight. Takes 40 gallons of sap to make one of syrup -- so it takes a long time to boil away.
Rough milled the new head casting flat today and a couple other pieces -- blocks that were very roughly cast -- no pattern, just carved out some sand for them -- like ingots.
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Good looking head. Glad you were able to work around the snow.
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Thanks B85V! Coming along slowly but surely.
I call the new one my experimenter's head. I can try different valve assemblies by bolting them to the new big flat boss. If one doesn't work out, I can just make another one without having to cast a whole new head, and bolt it in place. That's what I call planning for plan B!
I squared up a blob of roughly cast aluminum to fit the new valve space (shown lower right in the photo). I need to line bore it to take a long bronze rotary valve bushing. Well, half bore it. Basically cut a 1.050" D. semicircular channel along the top face. This would have been easy to do on my old Gingery lathe with the boring table and milling attachment I made and a fly cutter mounted between centers. One of those jobs where a horizontal mill would be ideal.
But now all I have access to is my Craftsman 12" x 42", and it doesn't have a boring table. I'm thinking about making up a new table for the Craftsman. Either that or, adapt the boring and milling rig from my Gingery to the larger lathe.
Anyway, here's the current state of affairs. I think this photo should be titled "Two heads are better than one."
(http://i786.photobucket.com/albums/yy150/vtsr/vtsr/TecumsehBuild/NewHead2better.jpg)
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I need to get in the truck and drive to VT and get some lessons in casting :smart:
I'm thinking about making up a new table for the Craftsman.
I think that is the way to go.
1. Because you can
2. Because it would be exactly as you want
3. Because I want to see it done.
Eric
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I need to get in the truck and drive to VT and get some lessons in casting :smart:
Sure. But better make it after mud season, the fifth season of the year is upon us -- the thirty days surrounding the day taxes are due, when Vermont is covered with mud!
As for the table, I made a small temporary one, but want to cast a larger permanent version in iron after the weather warms and the land is dry.
For the permanent version, I want to make something similar to the Myford's Super 7 cross slide (preferably the long version) , but altered fit the Craftsman/Atlas lathe saddle's dovetail ways.
I very much like the British cross slide system. With a similar cross slide I could then also easily build lathe accessories to fit -- as described in UK books by Tubal Cain, JA Radford, and others.
What I would need for that are some basic measurements of the Myford cross slide, and then I could draw up the Atlas version to suit.
Mainly I need the length and width of the table, the Tee groove size and locations, and the location and size of the pivot hole for the top slide. If anyon could help with those, I'd be greatly obliged!
As for the smaller temporary table, I was looking through my scrap bin for something over an inch thick to make into a table of about 4"x4" in size. All I found was a slab of 4" diameter round, about 1-1/2" thick that someone had given me. It was some kind of machining mistake, and had 4 tapped holes in it and some shoulders one side, and a big cone shaped depression in the center of the other side. Outside was still raw, and it was stamped 2021-T4, so good stuff!
I cleaned it up, cut off the shoulders to flatten the top, and bored out the depression on the bottom side to fit the circular dovetailed pedestal on the Craftsman cross slide. I haven't finished it yet -- I need to put in the locking screws and pins. Though small and round, it does look to have some advantages, since it is easily rotable. Some tommy bars, indexing marks and a pointer and it could be used as a rotary table, as well as a small boring table. I also just set my vertical slide from the Gingery lathe project on top of the table, and it seems to fit there as well. I'll need to drill and tap new holes for that.
Unfortunately there's not a lot of bearing, and the center post of the cross slide is not the best design for taking heavy loads, so I'll need to be careful. A much better solution will be the larger cast iron Myford style cross slide that I hope to build, since it will bear all the way across the saddle, instead of at one point on the dovetail pedestal.
Anyway here are some photos showing the construction of the Craftsman saddle, and the new small boring/rotary table and the vertical slide setup:
The small table cleaned up and bored. The Sears Craftsman/Atlas 12" cross slide has dovetail ways, and a dovetailed post for accepting the top slide.
(http://i786.photobucket.com/albums/yy150/vtsr/vtsr/TecumsehBuild/AtlasSlide1.jpg)
The small table mounted in place. It still needs fixing screws and pins.
(http://i786.photobucket.com/albums/yy150/vtsr/vtsr/TecumsehBuild/AtlasSlide2.jpg)
Trying my smaller lathe's vertical slide to see if it will fit.
(http://i786.photobucket.com/albums/yy150/vtsr/vtsr/TecumsehBuild/AtlasSlide3.jpg)
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Today I drilled and bored out the valve housing block to fit a piece of red brass pipe, which will serve as a valve liner. Should be easy to replace, and the exhaust will pass through axially, so I can route it via the threaded pipe to a condenser some day.
The steam entry will be perpendicular to the valve.
Today I also bored the pipe true and then lapped it with a lead lap.
After that I turned a valve out of a piece of hot rolled rod and made it a nice close fit to the liner.
I milled a slot shaped port in the head and a matching port in the valve housing. Haven't milled ports in the liner yet, but hope to tomorrow
(http://i786.photobucket.com/albums/yy150/vtsr/vtsr/TecumsehBuild/NewHeadbored2.jpg)
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(http://i786.photobucket.com/albums/yy150/vtsr/vtsr/TecumsehBuild/TecumsehNewValve1.jpg)
I've been working on the rotary valve and it's finally finished. The exhaust ports through the aft portion of the valve which is hollow. The steam section is solid and follows a channel connecting a steam port and a head port. It was tricky working out the sizes of the ports and channels to get the valve timing.
I milled the ports in the valve spindle with a somewhat iffy collet spinner -- tough getting it not to rotate while milling, but I took light cuts.
I do have a massive very old 10" dividing head, it weighs 125 lbs and I picked it up for $50 at an auction -- including an attached three jaw chuck and a tailstock. But it doesn't have division plates or an index arm. I hope to make the parts I need for it -- would have been nice to have for this job. Looking at it carefully I just found the maker's name -- it's Kempsmith. I'm going to guess from the lettering style that it is near turn of the century in age.
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First run! :ddb:
[embed=425,349]<iframe src="http://player.vimeo.com/video/65002574" width="425" height="349" frameborder="0" webkitAllowFullScreen mozallowfullscreen allowFullScreen></iframe> <p><a href="http://vimeo.com/65002574">FirstRun4CyConv</a> from <a href="http://vimeo.com/user9419463">vtdiy.</a> on <a href="http://vimeo.com">Vimeo</a>.</p>[/embed]
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Excellent news! Looks good, sounds good :wave:
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brill work :thumbup:
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WOW!! :bugeye:
Great work VT! :clap: :clap:
It really looks good, too........ :thumbup:
David D
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Thanks awemawson, krv3000, and Stilldrillin!! :beer:
Well it's a start. I used the free Visual Analyzer program on the audio portion of the video, and it looks like the engine is turning a little under 700 RPM @ 100 PSI compressed air.
(Visual Analyzer: http://www.sillanumsoft.org/prod01.htm )
I'd like to start on making it a real steam engine, now. Lagging, release valve, pumps, oiling, boiler.
The compressed air isn't doing it any favors re. power output. The valve inlet timing has a fairly short cutoff intended for steam and that doesn't help any on compressed air. And I also would like to get closer to 200 lbs pressure.
Presently just for a ballpark estimate:
Pressure say 75 lb
Length of stroke 2.25" or .1875'
Area of piston 5.41 sq in
Number of power strokes 670/min
P x L x A x N = 50972
Power = 50972/33000 = 1.5 Hp