On Thu, 16 Apr 2015 13:25:17 -0700, wrote:

On Thu, 16 Apr 2015 11:04:10 -0700, wrote:

All-
I need to put an o-ring groove in the underside of 500 1/4-20 flathead
screws. So I need to make a groove tool to do the job. A straight
groove tool won't work because the sides of the groove are curved. I
have made tools like this before but this is a small one and I'm
machining 304 SS so I need carbide and only want to make the tool
once. So I think to find out what radii to grind the sides of the tool
can be determined by drawing the screw head with the groove in it.
Then extend the sides of the head until they meet. Then mirror the
drawing around that point. Then I can directly measure with the cad
program the two different radii of the sides of the groove. Am I
correct?
Thanks,
Eric
I know it's bad form to reply to your own post but I obviously need to
make a clarification. The groove is going into an angled surface and
is normal to that surface, not to either the axis of the screw or the
top face of the screw. I alread know I need a 5/16" dia o-ring. But
since the groove is normal to the angled face the sides of the groove
will have larger radii than the radius of 5/16".
Eric
I know, I know, replying to a post that is a reply to my own post is
really bad form. Makes me look weird, like jon banquer. Anyway, after
looking at the groove drawing I know I am correct. But please feel
free to correct me if I am wrong. And don't tell banquer that I am
replying to my own posts, he might think I'm like him.
Eric