a Jerry Howell "duplex vacuum" stirling engine build

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madjackghengis:
Thanks for all the encouragement and kind words my friends, it is almost as good as a visit, and far better than it was before we could share like this. Didn't get a lot more done, but did move forward some, and got some figuring done.

I took a piece of ali plate which happened to have four holes in the same place as the top of my cylinder, screwed the cylinder to it, and squared it up in the mill vise so I could drill the holes for attaching it to the base and closing off the hot end later. I'm having to "manage" the screw holes because I've got a .921 bore, and the plans call for a .750 bore, but I figure the engine should be more inclined to rpm than torque with a larger bore and the same stroke. I chose a piece of brass tubing from a water closet valve, which is an inch o.d., because it was in my scrap box, and I didn't want to turn a piece of solid bar stock into tubing.

The stanchion holes are #10-24, so I chose eight #4-40's for closing the bottom, probably overkill, but I'm hoping to have a good enough seal to put a small pressure pump to self-presurize the engine once it's operational.

eight drilled and tapped 4-40 holes, ready to go back to the lathe to get counterbored for the insulation around the stainless hot end, which will go in this end.

Here is one side of one of the stanchions, the scribed circle toward the top will take a ball bearing in each, with an oiler, and the scribed circle on the right end, will carry the shaft, in bronze bearings, which will actuate the displacer piston. With the two sides being pieces of angle, and the scribing on the outside, I believe I will clamp them together for the basic holes to get them perfectly lined up, and then bore each separate, to avoid losing alignment trying to bore across the width of the cylinder. That's about all I got done yesterday as I didn't take pictures of washing lawnmower engine parts, I'm just amazed that an engine so old and hard used can wash in a tank and look like new with hundreds of hours on it. Hopefully I can get the stanchions drilled and reamed, and maybe got a start on lapping the cylinder. I want to try to get it straight and round within a ten of a thousandth, so I can fit the piston that tight. The bore of the brass cylinder lining looks very smooth, but will show up quite different once some cross-hatch is introduced, but brass laps and polishes very well and quickly. By the way, this one should be fairly easy to get running as it does run off a an alcohol flame or a butane flame. When I get to my LTD stirling, I intend to try I believe it was Nick's suggestion of a rice cake?, in any case, I like that idea, as they certainly aren't made to eat. I'm saving that project for some bit more practice lapping. :nrocks: :bugeye: :beer: Cheers, all, thanks for the inspiration. mad jack

Stilldrillin:
Hey Jack! :wave:

You got away before I was ready! ::)

Nice to see you are producing, and showing in your usual manner and speed. :clap: :clap: :thumbup:

I'm on board and watching, now. Keep 'em coming..... :D

David D

madjackghengis:

--- Quote from: Dean W on September 29, 2011, 07:02:14 PM ---You're off to a great start there, Jack. Nice pics, too!
These are a good running engine, and the late Mr. Howell did his homework for us. I built one
a while back, and it runs for me every time I ask it. I'll be watching and re-living the build!

Dean

--- End quote ---
Hi Dean, Nick, Still and all, if I'm not mistaken Dean, it was your build that got me onto this engine, and you gave me Jerry's address to get the plans from. I'm happy to know it's still running great. I have high hopes. I appreciate the thoughts on flood damage, but if you live on a creek, you have to live with high water times, and I wouldn't give up my corner of the woods for less than about half a ton of russian ammo, and my life. I'm happy to have such a forum to share with it is both an honor and a privilege. mad jack

madjackghengis:
Hi all, I haven't got a whole lot more done, but a little bit, so I'll post it now, and keep it simple. I took the blued and scribed stanchion and clamped it in my mill vise, with a parallel under it to get it aligned, and center drilled it, then drilled just an 1/8th inch hole at each location, so I can find them when I put this piece face down against the other side, to locate the holes in it accurately.

center drilling the first hole, then following with the 1/8th in drill

drilling through the second hole, which is the crank bearing hole, and will be bored out for the race once both sides are drilled.

having drilled through both holes, the scribed side is removed, aligned with the second half, which must go underneath, and using the mounting holes, the two sides are aligned for drilling through.

The second hole will carry the displacer arm shaft, so it is step drilled and then reamed out .312 for bronze bushings.

with the second hole drilled and reamed, the first hole is now bored out to .375 for the ball bearing, .125 deep on the inside of the stanchion, first cut.

after a couple more cuts, the counter bore is on size, and now this side is removed, and the second side taken out from underneath and flipped, to show off its inside for its proper boring.

having knocked the blank down onto a parallel, the first boring cut is taken.

A couple more cuts, measuring, and this counterbore is on size and depth, now it is time for the excess to be cut out, and the stanchions will take their actual shape and place in the next installment.

The two stanchions, showing both the side scribed for cutting out, and the reamed holes for the displacer arm, and the counter bore of the far side, visible now. I think the next time will have to have the stanchions fit, and start working on lapping, so I can turn a piston and put in a crank. Ta ta for now, :beer: Cheers, mad jack

sbwhart:
Neat:- Very Neat

:thumbup: :thumbup: :thumbup: :thumbup:

Stew

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