Die diameter

I wish to die down a brass rod to 1/4" BSP. To what diameter do I need to turn the brass rod down to get a near perfect thread?.Thankyou.

0.518"

HI Roger
Have you got a 'Zeus' book?. It has all the tapping & die sizes. OD, Core dia. etc, well worth having one by your lathe.

George.

To anyone without a set of Zeus Charts.

INVALUABLE!

I still have and use the set (and the Unbrako Allen keys!) from when I was a first year Apprentice, in 1958. (Now grubby, but readable) I have other, later, versions, but the old one sees the most use in the shop. The others are reference, indoors, but do not necessarily contain some of the info from the earliest editions.

Yes, I use other books as well, Sparey, Ian Bradley, Tubal Cain, Workshop Practice Series, etc. They all have their uses as sources of information, on different subjects..

Howard

Perfect,Thankyou

My oldest edition is now 1974; so far as I can see from this and subsequent editions, over the years BA threads have been dropped and NC coding and drawing symbols added.

Congratulations on sticking to the 1958 version whose print was, I imagine, difficult to read in places.

If JB did not read it off a hard copy chart of some kind he could simply have searched for ''BSP thread dimensions'' on the internet. First hit on ''goggle'' supplied the result reported. Anyone can do it - even me!

That's what I usually do just Google BSP, Whitworth, BA etc followed by "thread data"

Though when I'm in the shed out comes the Zeuz