Socket Head Fastener

Or, alternatively, can you increase the counterbore? That might be an easier solution, if a cursory search for a smaller socket head does turn up anything in the first 30 minutes. Just buy the bit and go to town...
Dave

There was a revision in 1960 and the current socket heads are referred to as "1960 series", the older fasteners are "1936 series". Googling
"1936 series" "socket head"
turned up this link which lists a few in 5/8", among others...
Ned Simmons

You're absolutely certain that the THREAD is 5/8"? Clearance holes for socket head SHOULDER screws would be one size larger (the thread is one size smaller than the shoulder). Here's what might be a remote possiblity . . . if someone had created a clearance hole for a shoulder screw BY MISTAKE and left the counterbore the correct size for the actual thread (a regular socket head cap screw), you would seemingly have an undersize counterbore if you tried to put in a regular socket head cap screw that fit the clearance hole (would be too big for the actual female thread). I only mention this because it's not clear whether you are able to observe the female thread directly or just extrapolated what thread you should have from the size of the clearance hole.
Mark 'Sporky' Stapleton Watermark Design, LLC
Larry767 wrote: > > We are working on some old equipment that has some 5/8" socket head > screws that need replacing. We ordered new fasteners and the heads > came in at the standard 0.938" diameter. The old fasteners we are > replacing have a head diameter that is approx. 0.860". The > counterbores in the part are sized accordingly so the new fasteners > will not fit. > > My question is, was there a change to the ANSI standards at some point > to increase the head diameter or are these fasteners just non ANSI > (i.e. produced in some non-ANSI abiding country)? Is it possible to > buy a 5/8" sockete head cap screw with a smaller head diameter anywhere?

I forgot to mention, the head diameter on your old fasteners matches that of the 1936 cap screws.
Ned Simmons

If the bolts are not critical to safety, I suppose you ground the heads as required?
Brian W

Thanks. Here is a link explaining the 1936 vs 1960 series moniker.
* What I don't see is a chart confirming the head diameter of the 1936 series 5/8" cap screw. You say in a later reply that it is .860 but can you point me to a reference chart to confirm my own curiousity?
Thanks.

Check with The Ferry Cap & Set Screw Co, 2151 Scranton Rd Cleveland, OH 44113-3578
They had/have a spline head screw (not socket) that may work for your application. Even if the collar is slightly larger than your c'bore, it can be ground down much easier than that of a socket head screw. They may be able to solve your problem.
Jim Y

I found these that may help:
Jim Y
application. Even if the than that of a

*> I found the dimensions in a pre-1960 copy of Machinery's Handbook. If you want a copy and are in the US, email me a fax number and I'll be happy to send the page.
Ned Simmons

Ned, I am in Canada. Could you fax the page to 306-931-2442?
My local bolt supplier also faxed me a copy of a chart referencing American Standard B18.3-1947 confirming the .863-.875 head dimension in that era.
Thanks everyone,
Larry Jorgenson Saskatoon, SK

That12-point head seemed like a worthy suggestion. I have seen "NASA" screw heads of this general form. I wondered about the strength implications - you usually suppose an "Allen head" (= socket head) is high test material. These, I see are made to order "in any grade"
Brian Whatcott Altus OK
application. Even if the than that of a