bsw threads

[david bennett 8Participant @davidbennett8]

I have seen reports that these do not exist. Yes they do! I recently bought this incomplete set. They go from 1/4" bsw to 5/64" bsw. I would guess the missing die is 9/64".Remaining are 5/64" 7/64" and 11/64", along with the the usual sizes. Unfortunately no  64" ths taps.

Edited By david bennett 8 on 22/08/2023 17:40:22

Edited By david bennett 8 on 22/08/2023 17:42:59

Edited By david bennett 8 on 22/08/2023 17:45:34

[david bennett 8Participant @davidbennett8]

1/64″ increments

[SillyOldDufferModerator @sillyoldduffer]

Well, although there was a Whitworth Standard for Screws for Instrument and Watchmakers, it wasn't included in the British Standard (because BA was adopted for that sort of work.) So can't be BSW in the purist sense.

Probably not Whitworth though because the set is American, and they never went in for Whitworth much! I reckon it's ASME, the US National Standard thread form miniaturised for Instrument and Watchmakers.

Can you measure a flank angle? Whitworth will be 55°, ASME 60°.

Interesting find whatever it is.

Dave

[Michael GilliganParticipant @michaelgilligan61133]

VERY nice, David

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MichaelG.

[david bennett 8Participant @davidbennett8]

Dave, I threaded a piece of brass with the Greenfield 1/4" die. Although difficult to show, it is clearly 55 degrees, a very good match for an imperial thread gauge. You will know that Greenfield, although American, exported internationally to customers standards.

Edited By david bennett 8 on 22/08/2023 21:38:41

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