I've machined Teflon, speed does not seem to be an issue as in other plastics - it does not melt easily if at all, think frying pan.
Sharp HHS tooling works fine.
post pics when you're done please.
I think you are proposing to used this in on of the low temperature Stirling engines which should be fine as far as I know never having built one :-} but please read this quote.
Safety
While PTFE itself is chemically inert and non-toxic, it begins to deteriorate after the temperature of cookware reaches about 500 °F (260 °C), and decompose above 660 °F (350 °C).[12] These degradation products can be lethal to birds, and can cause flu-like symptoms in humans.
By comparison, cooking fats, oils, and butter will begin to scorch and smoke at about 392 °F (200 °C), and meat is usually fried between 400450 °F (200230 °C), but empty cookware can exceed this temperature if left unattended on a hot burner.
A 1959 study, (conducted before the U.S. Food and Drug Administration approved the material for use in food processing equipment) showed that the toxicity of fumes given off by the coated pan on dry heating was less than that of fumes given off by ordinary cooking oils.
http://uk.answers.yahoo.com/question/index?qid=20080706100329AAIzM68
- Scott