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


I need to put an o-ring groove in the underside of 500 1/4-20 flathead
screws.
snip
Might be overkill. What sort of pressures are involved?
What are you sealing? Was a flat rubber/elastomer
(urethane?) washer evaluated? How about a combination seal
and retaining compound like RTV or Loctite?

If the O-ring groove is mandatory, how about a hollow mill?
with the correct geometry? Given the problems in holding/
handling you might be better off making the complete screw
from bar stock, although slotting the head may be a
challenge. Do you have a CNC with a bar puller? How long is
the thread? Style of head/drive?




--
Unka' George

"Gold is the money of kings,
silver is the money of gentlemen,
barter is the money of peasants,
but debt is the money of slaves"

-Norm Franz, "Money and Wealth in the New Millenium"