Stirlingengineforum.com

Can anyone tell me where i can get an off the shelf 100mm graphite piston. Has any one tried using other types of pistons, eg ptfe, teflon, peek etc

Adam, the only shelf you'll find a piston like that is your's when you make it. I don't think Airpot make them that big, but you could ask, and if you are based in USA you might even get a free sample. If I were to make one, I would make an aluminium inner piston , and fit a hollow graphite cylinder over that, 100 mm is quite large, and the metal skeleton would give it strength, just make it fairly lose fitting inside, and very accurate in the bore, which must be very close tolerance in diameter down its bore. The bore must have a highly polished finish to it, or the graphite piston will be a waste of time and money, but if you get it right you probably can't do any better.
Personally I use a well fitting, light weight cast iron piston in my engines. A 100 mm piston could be made with a crown thickness of 5 or 6 mm, and the skirt about 3 mm, or even thinner, the con rod connected to a gudgion block attached by screws to the crown of the piston. Use a cast iron cylinder, and NO rings.
Ian S C

thank you Ian for you advice
have u pictures of your engines.

If you look to the right side of the page, you will see Images; 15, click on the 15 and that will take you to my gallery. Ian S C

Hello Adam,

You will find the graphite rod stock needed from the link below to make such a piston, however you will need a lathe to finish the piston.

http://aeroconsystems.com/cart/graphite-rods/

Adam, just looking at the web site produced by the SIUE Stirling team, you should be able to get a shorter length of 4 inch graphite, perhaps aim for about 6 inches, enough for two pistons, just in case you spoil one.
Ian S C