"Pete C." wrote in message
ster.com...

Bob La Londe wrote:

"Bob La Londe" wrote in message
...
So what's the

spproscribedsp

prescribed method? I expect I need a pretty consistent radius
bottom. What's the best way. Make a rough semi V lathe bit, and then
make a decent round one to finish?

LOL.

Silicone o-ring for modest heat. Upto about 325 degrees.



Most O-rings I look at are seated in square grooves. I believe you need
the extra space afforded by the square groove to allow the O-ring to
deform and seal properly. For a piston though, you should probably be
looking at cup seals and the like on McMaster.com.

Not an engine piston. A modest temp single stroke hand injection pump
piston. After I posted I was thinking a square groove might work better.
Thanks. I have not grooved the piston itself yet.