Series 1936 SHCS head dimensions 1 1/4"-7

Like this?


There is no min, they can be sharp.
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P.E. Metallurgy, consulting work welcomed

thanks Ed.
Definitely an A for effort and especially a speedy response.
That info looks to be the modern series 1960 SHCS.

I should have been clearer. We need to replace some SHCS on older equipment.
There were genuine 1936 series SHCS installed.
The locations of the counterbores prevent enlarging the counterbores to accept modern 1960 Series SHCScrews.
Unfortunately the availability of the used original SHCS to check dimensions is not good.
Also unfortunately new 1-1/4" Series 1936 SHCScrews is a BIG problem.

From the NONMANDATORY APPENDIX D tucked at the very end of ASME B18.3 2003.


Holokrome has a simplifed reference table for dimensions of 1936 series SHCS.
it lacks the details about underhead radiuses and head chamfers.

I know that the aerospace standard is different, and there are some common alternate head sizes.
We used to have custom made 12-point bolts that would fit where SHCS were standard.
It wouldn't surprise me if the historical spec didn't have a defined radius limit.

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P.E. Metallurgy, consulting work welcomed

There are some hints on the web that BS 2470 might be the same as the 1936 series ASME standard.

Can you just reduce the OD of the heads of modern SHCSs? Chuck them in a lathe and machine off a sufficient amount.

They will certainly have to do something as a sort as no such obsolete screw will be on the shelf.

Thanks MintJulep.
That BS 2470 Standard was VERY helpful.

Ours are 1-1/4"-7 SHCS.
Looks like the old underhead radius was undefined but probably .05" or a little more, compared to about .06" max and possible a sophisticated profile on modern SHCS.

The old SHCSs head ODs reportedly were 1.780".
The BS Standard says 1.750" Max.
Hmmm.

Got a feeling this is not over yet.

Dan T