FIRST BUILD OF POP CAN ENGINE HELP PLEASE!!

[KurtB]

hi i have spend 4 full days next to non stop working on the engine and little sleep... gonna rip my hair out soon lol... i have built it and took it apart a million times and several fresh rebuilds, and all ive gotten out of that is the balloon diaphragm moves a bit when the con rod is disconnected, so it getting something but not enuf... im thinking my pressure chamber might not be sealed enuf at the top for the displacers con rod.. whats the best way to seal the displacers con rod at the top of the pressure chamber? please help... like ive said ive spend many many hours and have almost NOTHING!!

[theropod2]

Kurt,

My advice is to back away from the project for a few days and let the stress level die down. When you have regained some zen pick the motor back up and see if you can't figure it out.

Yes, the displacer rod/gland needs to be fairly air tight. You might try a glass bead there. In the walking beam our host supplies the drawings for I used an expended 308 Winchester shell casing with the spent primer removed. I fixed the shell casing base down with the primer hole drilled out to 1/8" for the brazing rod I used, and a guide rod from a DVD drive on the top. This length allowed me to get a good smooth pathway for the rod with very little friction. A simple length of copper, or steel, tube would have worked just as well. I knew the rifle cartridge was straight and the broad base made it easy to solder to the displacer cool end cap.

Be sure the membrane is loose enough to not bind the power "piston" function.

I'd look real hard at the flywheel too. A heavy flywheel will still work with an engine that runs well, but on a marginal engine that might be holding you back. I found that I had to add weight to offset the displacer assembly, and that was accomplished by trial and error. I used some double sided tape to add thin lead strips to the outer edge of the flywheel opposite the crank throw. Actually I found that with just a tiny bit of offset from dead center helped the engine spin through the compression point. I think that weight was in the trailing position from TDC.

Hopefully I haven't confused you too much.

R

[KurtB]

what do u mean by glass bead?

[KurtB]

I think the problem is my displacer and pressure chamber... Can someone please tell me (hopefully in detail) the best and easiest way to make one and be sealed? Please

[jimlarsen]

Check out the Troubleshooting Tips on the StirlingBuilder site. This link should get you there:

http://sites.google.com/site/stirlingbu ... oting-tips

The displacer needs to move freely with as little friction as possible, with as little leaking as possible. Sometimes a drop of oil helps slow the air leak. It is quite easy to make the hole too large. Also, the displacer needs to travel as far as is reasonably possible wtihout contacting the ends of the pressure chamber.

These engines barely have enough power to overcome their own friction and run, so you must pay meticulous attention to friction and pressure leaks. It is more like building a clock than a motor.

[theropod2]

what do u mean by glass bead?

A glass bead with a very close match between the inner diameter and the shaft outer diameter will provide a very low friction surface that will last a long time. Most hobby stores, or wally world, will have a wide selection of beads with all sizes of threading holes. If one had 2 of these that matched the shaft size one could epoxy one to one end of a stiff tube and one to the other. Leaving the shaft in place until the epoxy cures will create a low friction gland/bearing.

RS

[Ian S C]

Mum, or Grandma,or wife, a good place to start looking for beads, one of them will have a broke necklace. Could be used as main shaft bearing as well. Ian S C