On Thu, 23 Apr 2015 11:14:09 -0500, F. George McDuffee
wrote:

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
This just showed up in my inbox. They may have something in
stock.
http://tinyurl.com/pe2y3bm
Greetings George,
Thanks for posting the link but what I need is what I described in the
first place. I appreciate all the advice about different screws but
the customer wants what he wants. I also was surprised that only one
person directly addressed the original question, the one about
geometery.
Eric