1/8 x 48 BSF

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.

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

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

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'

Nick are the sizes you quote not Whitworth rather than BSF ?

Roy

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!

they must exist as i have got one and a1/8 x 60

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 !

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