1/8th BSP male thread "taping" size?

Hi,

I want to thread a rod 1/8" BSP, but I cannot find out what the OD would need to be. I have a die nut on order. I can easily find out that a taping hole size is 8.6mm (if I remember correctly) for a female thread, but I can't find the equivalent for a male thread.

Am I being thick? Is it the same size whether male or female threads?

I am not sufficiently skilled to thread on the lathe, nor do I want to delay this job whilst I become so!

Thanks

Andy.

Edited By Andy Collins on 11/07/2014 12:59:21

This should tell you what you need to know.

http://en.wikipedia.org/wiki/British_Standard_Pipe

Phil

Andy, Zeus book is the place, every machinist needs one!

O/D is .383 bar size for your die

tapping size 8.75mm (.3445) or alternate 11/32" (.3438"

Zeus also give all other data , effective dia, pitch, depth etc, etc.

regards John

Andy,

Concur with JohnF; Zeus book in the workshop, overalls, coat pocket ... the engineers ready reckoner / ref book, a minimum must for any ME.

George

yep, still got my Zeus from 1980, bought it as an apprentice

Still got mine from 1960 but it's a bit tattered! Have anew version as well metric revision just wish I could get one of the originals. Also have a pretty good one form WW2 -- inherited I might add!

I was presented with my Zeus book on day 1 of my apprenticeship in September 1962. Still got it and still using it, occasionaly. I have to confess to having a new Metric one as well. Nobody should be allowed near a lathe or a mill without one in their pocket. It should be a legal requirement.

Hi, I have three, one from 1972, one from 1978 and one from somewhere in the 80's, all are metric revised. The 1978 one let me down once as it had a printing error on the last page of the solution of rght angled triangles. In the column of "DATA KNOWN" on the sixth line down, the letters were wrong, can't remember what they were as I've scrached them out and written the correct two in, which are; b & B.

I think my 1972 one cost about 50p or 60p ish, the 1978 one was 75p cause it's got it written in a circle on the front, can't remember what the 80's one cost but probably close to or over £1.00.

In the 1958 Buck & Hickman ltd. catalogue, they advertised Zeus precision data charts and reference tables for 2 Shillings and Six pence (2/6) 12.5 pence in todays money, by 1964 they were 4/6 22.5 pence in todays money.

Regards Nick.

P.S. Buck & Hickman currently have them for £4.71 excluding any VAT or PP.

Edited By Nicholas Farr on 12/07/2014 11:28:16

I've got a copy of Zeus somewhere, but no idea where, so it looks like I'm operating illegally.

Andy: If you have ordered a die nut, as opposed to a circular split die, then you're going to have a problem. Die nuts are intended for cleaning damaged and dirty threads, not for cutting them in the first place.

Regards,

Andrew

Good point concerning the purpose of die nuts and the difference between them and dies.

However there are also hexagon shaped un-split dies which look at first glance the same as die-nuts but which will cut a satisfactory thread from scratch. Especially if buying surplus it can be a toss up as to which you get.

As I recall things such hexagon unsplit dies were made in pipe sizes for use in a special diestock with a carrier for an alignment bush. In use the bush and die pertaining to the pipe size would be fitted. The pipe was slid through the bush and the die wound on to produce the thread. Ordinary workers could easily produce accurate threads on site. These days the powered pipe threading machines fill the same niche.

Care is needed when looking for die-nuts and hexagon dies in metric sizes as many of the truely crappy bottom of the market bargain tap and die sets include dies of this form. Regrettably performance varies from insert cheese only please to distinctly unsatisfactory.

Clive

Clive the dies you are thinking of did have a hex or octagonal drive to fit the ratchet at the guide end but the actual business end is more like a diehead.

Still use mine on the larger model hit & miss engine exhausts

J

Jason

Nice bit of kit there. Turns out I have got one such die marked Beaver 3/8 W in the "I really should bin them" box. Always wondered what it fitted. Now I know. Thanks for the picture.

However I have had a full hex pipe die through my hands which, according to the man I passed it on to, fitted a hex carrier diestock assembly essentially similar to the usual type save for the different recess shape and guide assembly. 30 or so years back so don't recall if I was simply told about it or actually saw it.

Clive

Hi All,

Thanks for the responses- I think I assumed that the OD of an un-cut thread started off bigger, and the action of cutting reduced it. I sit corrected- the OD before and after cutting a thread is the same.

I do have a Zeus book, dated '65...a year younger than me, and I don't know why I didn't look in there first- I think I assumed a BSP thread would not be mentioned.

Andrew- a typo- I did, in fact order a split die, but even so, I didn't know there was a difference between a split die and a die-nut!

Thanks again- threads cut successfully!

Andy.

With ductile materials (e.g. copper, aluminium), it can pay to use slightly undersize material as a degree of extrusion takes place when cutting the thread.

Neil