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[TakeawayParticipant @takeaway]

I have just finished cleaning up a clutch of small taps which came from an old stagers tool chest. Amongst them was a tap marked “1/8 x 48tpi”. In all the time I spent earning a crust in the engineering industry I never came across anything like this. Mind you, I had never seen 1/16″ Whit or 3/32″ Whit either but I now have three of each.

 

Does anyone know if these tiny taps where favoured by particular users – say clock makers or instrument makers?

 

Thanks in advance

Stuart

[TakeawayParticipant @takeaway]

Unusual tap.

[KWILParticipant @kwil]

I have used 3/32 Whit both LH and RH on a gun back sight to remake a broken lead screw.I probably have a 1/8 x 48 whit somewhere as well.

[JasonBModerator @jasonb]

I thought 1/8″ Whit was 40tpi, at least teh taps that I have are?

 

J

[Terry LaneParticipant @terrylane]

Yeah, 1/8″ x 48 tpi is BSF – you don’t often see ’em listed – most data charts only go down to 3/16 BSF, however, I notice they are available here

[TakeawayParticipant @takeaway]

Thanks to all the helpful remarks to my original posting on small threads and a special thanks to TEL for his very relevant observation.

Stuart

[BazyleParticipant @bazyle]

I have just bought 10BA screws only to find I had taken it for granted that small screws would be BA. In fact I needed 1/16×60. I suspect that in the first half of the last century small Whitworth was more common than BA as it was just the natural progression down the series. BA may have been adopted for the new fangled electrical equipment and spread out from there.

It might be interesting to look back at early ME designs to see what was called up but my collection only goes back to 1940’s

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