[R-390] R-390A set screw size

[roy.morgan at nist.gov]

Quoting Chris Kepus <ckepus at comcast.net>:

> Has anyone bothered to replace the Bristol set screws in the R-390A with
> allen or socket headed set screws? 

Chris,

No.

> Does anyone know the thread size of these set screws?  4-40, 6-32, 8-32 ????

Eight  Thirty-Six.
The driver needed is .096" diameter with 6 flutes.

I recently got a tap for the purpose of cleaning out the threads after
refinishing. Size 8-36.

> In looking at the McMaster-Carr set screw selections,

There was a post on the Collins list just today about where to get the Bristol
set screws: If I remember right, McMaster Carr does not list in the catalog the
Bristol set screws, but if you call them, or email them, they likely will find
some for you.  (Wanna split a box of 100 or a gross?)

The Bristol Wrench Company makes the wrenches (L-keys, screwdriver handles with
bits, and T-drivers:
http://www.bristolwrench.com/
They do not seem to make the screws.

You can and should get Bristol drivers made by the Bristol Wrench Company from
Max Gain Systems:
http://www.mgs4u.com/


Roy

Roy Morgan
13033 Downey Mill Road
Lovettsville VA 20180