Simple graphite/epoxy piston

[pyroevil]

Hi everybody !

It's my first post here. I not build a entire stirling engine for now but I think about it for many years. I'm a bit to busy.
I'm starting 3-4 years ago to cast epoxy/graphite piston and I want to share this idea. I don't know if somebody
try it but what I do is really simple:

- Just mix together Graphite powder ( sold in hardware store or Ebay to lubricate door lock ) and Epoxy.
- Just pour it in you cylinder and let's it's dry.

For minimise skrinking when epoxy cure , I make a clay piece in the center of the cylinder and pour over it. When cure , I remove the
clay and it's give a real engine piston shape ( with empty space at the bottom ).

My inspiration come from the well know JBWeld piston trick. I don't find the best ratio between Graphite Powder and Epoxy for now.
I can show some picture of some of those I made 3- years ago soon.

What did you think about this cheap piston solution ?

[SIUE Stirling Team]

Hi Pyroevil

That is a good idea, when my team was formed a year ago, we tried to do the same thing but never added graphite.
Thankfully a machine shop granted us access to use their machinery on second shift.

If you can, please post photos.


Joshua & the Team

[Ian S C]

Pyroevil, have you tried both plain epoxy, and epoxy plus graphite pistons in a Stirling Engine, to compare the advantage of the graphite, every advantage is worth fighting for, and this method is cheaper than the graphite rod. Ian S C

[pyroevil]

no sorry , like I said I never build a entire engine. Graphite-Epoxy feel more smoother on touch and seem to slide better in cylinder. But no accurate prove that's is better then epoxy only piston. :)

Photo coming soon if I found this old piston in my garage :P

[pyroevil]

One piston is really smooth and well done I think ( except about the bottom hole not centered)
The one with "bubbles" in it is because I put oil for the release of the mold ... not a good idea.

[Ian S C]

Thanks for the photos Pyroevil. Ian S C

[jimlarsen]

Do you have to use a release agent in the mold, or is the graphite enough to prevent the piston from sticking in the mold?

[pyroevil]

if I remember ... not really. After cured I put it in a cold place ( freezer ) for one or two hours and I heat a bit the copper ( mold ). The temperature difference make it released.