1/8 x 48 BSF

This topic has 9 replies, 8 voices, and was last updated 7 June 2022 at 10:32 by Samsaranda.

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7 June 2022 at 04:23 #600897
Ken edwards 1
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@kenedwards1
Hi all.

A friend has an old BSF tap and die set that has the smallest size (1/8) missing. I cannot find this size on any thread chart.. did it once exist ?

Ken.
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7 June 2022 at 04:23 #28733
Ken edwards 1
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@kenedwards1
7 June 2022 at 07:05 #600899
Hopper
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@hopper
Tracy Tools sells taps and dies in 1/8 x 48 BSF so it must have existed at some point — and indeed still does in this instance — but not in today's thread charts. Their stuff is usually good quality at a good price so worth buying to complete the set, if you would ever have any use for that size.

Edited By Hopper on 07/06/2022 07:06:08
7 June 2022 at 08:27 #600903
Michael Gilligan
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@michaelgilligan61133
Although the small BSF sizes were originally ‘standard’ … they were later [to use IT jargon] deprecated.

A strong preference was shown by BSI, for sizes below 1/4” to be BA

Very busy at the moment, but I will try to find the appropriate reference sometime.

MichaelG.

Edited By Michael Gilligan on 07/06/2022 08:28:57
7 June 2022 at 09:15 #600909
Nick Clarke 3
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@nickclarke3
Tap and Die Co List 1/16 x 60, 3/32 x 48 and 1/8 x 40 and from memory, when describing a steam donkey pump in a 1930s ME, LBSC mentioned an 1/8 x 60 'from brer Kennion'
7 June 2022 at 09:21 #600910
roy entwistle
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@royentwistle24699
Nick are the sizes you quote not Whitworth rather than BSF ?

Roy
7 June 2022 at 09:34 #600915
Nigel Graham 2
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@nigelgraham2
The smallest standard Whitworth threads are indeed as you list:

1/16 inch X 60

3/32 X 48

1/8 X 40

So are not arcane specials.

(Source: Bentley, W, Machine Shop Companion, The Bentley Publishing Co., 1913)

That book also gives useful change-wheel tables for cutting inch- and with 127T wheel, mm- pitch threads from a 4tpi lead-screw; which is that of the Harrison L5. Though of course useful to me only if my lathe's wheel set matches the tables!
7 June 2022 at 09:55 #600922
martin haysom
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@martinhaysom48469
they must exist as i have got one and a1/8 x 60
7 June 2022 at 10:07 #600925
Ken edwards 1
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@kenedwards1
Thanks guys.. I found them on the Tracy Tools site and was considering buying a tap as a gap filler, but may never get to use it, as hopper pointed out.. another problem is that the original dies were 1 inch, not 13/16 as most small sizes now seem to be.. just interested if it was originally a bona-fide size !
7 June 2022 at 10:32 #600928
Samsaranda
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@samsaranda
Original drawings for Allchin 1 1/2” scale traction engine list 3/32 thread, assumed they meant 3/32 x 48 whit, this thread is used on the oil delivery to the front wheel hubs, this is very small and at 48 tpi is very delicate. Dave W
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