a Jerry Howell "duplex vacuum" stirling engine build

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madjackghengis:

--- Quote from: Dean W on October 19, 2011, 05:18:59 PM ---You're making good progress, Jack.
If you have any trouble with that delrin seal, let me know. I have some ceramic sheeting left over from mine.
Plenty of it, if you need some.

--- End quote ---
Hi Dean, is that sheeting what Jerry suggests the use of for the hot cap? I hadn't bothered to look it up yet, I tend to get caught up in the machining, and let somethings go to the end. Thanks for the offer, and I think I will take you up on it when I get to a point where I've got a dimension for what I need. What a web site :beer:, imagine all those other people who go to such things to exchange make-up ideas and other such foolishness. :mmr: Engines R us :jaw: :beer: Cheers, mad jack

AndyB:
Hi Jack,

I have not been too keen on the idea of building these as they look too much like toys....until now! :doh:

Your build using whatever is to hand, and making it look easy and interesting, is fabulous! :bow: :bow:

You have given me an interest!! Looks like another project to line up! :bang:

I am definitely following :nrocks:

Andy

Dean W:

--- Quote from: madjackghengis on October 20, 2011, 01:17:45 PM ---Hi Dean, is that sheeting what Jerry suggests the use of for the hot cap?

--- End quote ---
Jack, yes, for the insulator that goes between the hot cap and the bottom of the power cylinder. It's a ceramic fiber stuff.
I got it from a place in Seattle that uses it for insulating kilns. Jerry Howell called it fiberfrax.
You know from the prints that it only needs a few square inches, but I had to buy two sq. feet, so I have a little extra. ; )
Send me a PM with your address and I'll shoot a piece your way.

Dean

madjackghengis:
Well, boys, I got a bit more done since the last post, too much work and having to adjust some figures to the different sizes I used makes my brain hurt sometimes.

I'm using a .965 bore instead of the .750 bore, and chose to increase the stroke from 3/4 in to 7/8ths in, so I took some safety wire and wrapped it around the crankpin, cut it off a bit long, to test and see if the connecting rod would clear the bore.

another shot of the test piece

the jig with the wire showed plenty of room, so I soldered a couple pieces of flat brass together to make the split con rod out of.

the pieces are about half an inch wide, and a bit of 2.5 long, they will be soldered into a bushing on the big end, and each small end will be on either side of the displace rod bushing, which goes up through the middle of the power piston, necessitating this two piece rod.

I put the pieces in the vise and milled one edge to get parallel, then put the pieces on a parallel, and pulled the vise up tight on the edges.

touching off on the edge of the vise with a wiggler, centered the spindle, then found the end and moved the table to position the spindle where the big end hole needs to be.

starting with a center drill, I'll step drill up and end with a .250 reamer.

one step drill

another step taking it to about .012 under, and then reaming it out in a slow and easy pass.

and the reamer, taking its light cut.

drilling the little end, #1 center drill, then a sixteenth, and an .082 ready for the reaming.

final reaming the wrist pin holes at .093, because that was my smallest reamer.

and here is the pair of connecting rod blanks, which will remain soldered together until their outline is cut and filed to final shape and profile. Once the actual limits of the power piston travel are observed, I will be able to jump into the making of the displacer piston, knowing how long it will be, and the length of its rod, after changing the other dimensions so fitting the power piston is next. Cheers, :beer: mad jack

NickG:
Beautifully crafted that Jack :thumbup: they do look really nice designs Howell's.

Nick

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