Socket Head Cap Screw Head Diameter?

[Larry767]

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?

 

[diamondjim]

Are you certain that they were not
16mm socket head capscrews?

 

[Larry767]

Positive. According to my books a DIN 912 M16 fastener should have a 24mm diameter head which would be 0.945". The diameter of these heads is approx. 21.8mm. It is definetly a 5/8-11 fastener. Thanks anyway.

 

[Larry767]

Found some additional info here:

http://www.techsavvy.com/industry/file/national/03v3f/6.html?id=107842&comp_id=03V3F&base_region=*

Now, can anyone point me to a chart specifying the head diameter of a 1936 Series socket head cap screw? I am being told that it is .860" by another internet surfer on the newsgroups.

 

[TBP]

I've got a 14th edition of Machinery'd Handbook, and it appears to show the head diameter as a max of 7/8" and a min of 0.863".