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

[Tmoose]

The 1936 series Socket Head Cap screws are typically smaller head Ø and hex socket than the modern 1960 series.

I can find Series 1936 sizes up to about 1".

Machinery's Handbook 16th Edition or ASA B18.3-1961 would probably have the answers of head diameter and edge radius/chamfer ( radius K in the attached image ) .
Any body have copies kicking around to consult ?

thanks,

Dan T

 

[EdStainless]

Like this?

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

 

[Tmoose]

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.

HEXAGON AND SPLINE SOCKET HEAD CAP SCREWS (1936 SERIES)
Prior to 1961, the 1936 Series of socket head cap screws were recognized as standard.
The 1936 Series screws are no longer stocked by screw manufacturers and are now available only on special order.
The major differences between the 1936 Series screws and the present standard screws (1960 Series) are that, for some
sizes, the 1936 Series had smaller head diameters and/or socket sizes and/or different thread lengths.

Users desiring additional information on the 1936 Series should refer to Appendix IV of ASA B18.3-1961, or
should consult socket screw manufacturers.​

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

SUPERSEDED DIMENSIONS — 1936 SERIES
Nominal size 1-1/4"
HEXAGON SOCKET SIZE MAX. 3/4" - 1960 series = 7/8"
HEAD DIAMETER MAX 1-3/4" - 1960 series = 1.875"
​

 

[EdStainless]

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.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[MintJulep]

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

https://www.fastenerdata.co.uk/1960-1936-socket-cap-screw

https://www.intafast.com/wp-content/uploads/2019/09/BS2470_ASME_1936_SKT_CAP.pdf

 

[SWComposites]

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

 

[TugboatEng]

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

 

[Tmoose]

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