On Fri, 7 May 2010 07:29:29 -0700, "Bob La Londe"
wrote:

So what's the proscribed 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?

Check this out:-

http://www.parker.com/literature/ORD...g_Handbook.pdf

Pretty much all you need to know about static and dynamic O-ring
seals.

"The shape of the seal groove is unimportant as long as it
results in proper compression of the seal between the
bottom of the groove and the cylinder wall, and provides
room for the compressed material to flow so that the seal is
not solidly confined between metal surfaces"