7/16" BSP Tap

Other day Malc the scrappie called in for a cuppa and to see if he could borrow a 7/16" BSP die.
I said I'd never heard of one, didn't mean to say there wasn't one, just I'd not heard of one.

He insisted he'd got the taps but no die.

So looked in various books, World screw threads, MH, Machinery screw threads book but all list 1/4", 3/8" then 1/2"
Even the specialised tap and die people don't list one.?

Anyway he popped in again to day with a tap and sure enough it's clearly stamped 7/16" BSP x 19 threads and it looks to be about the right size, looks close to a 3/4" UNF as a guide size.
Even took a picture

Anyone else heard or seen of a 7/16" BSP ??

John S.

Edited By John Stevenson on 20/03/2012 22:36:03

Parallel or Taper?

Ian

Not 1st April yet.

John

No, no joke, dead serious.

It was parallel but I even looked under tapered charts and nothing.

I have plenty of old engineering books, in fact I collect them and have about 7 that have nothing but screw threads in them. One list threads that obscure it even lists Manchester Plumbers Thread for copper pipe, only used by plumbers in the manchester area.

Also it lists the original Whitworth pipe threads which are very slightly different from the modern ones but again no 7/16"

John S.

Only reference I can find is for petcocks on old British motorcycles; like this:

http://www.steadfastcycles.com/cart/index.php?main_page=product_info&cPath=171_176&products_id=3917

Be about right; use an obscure thread nobody else uses, so the punter has to come to you for spares.

Regards,

Andrew

Tracy's have 7/16 x 19 taps and dies listed under specials.

J

Our spammers are up nice and early this morning!!!

Len.

Andrew,

Interesting link but for experiance all the fuel fittings I have come across are 1/4" pipe. This 7/16" pipe thread is about 3/4 to 7/8" outside diameter which is large for a motorcycle fuel fitting.

Jason,

The tracy taps are 7/16" OD pipe is different in that the size is the hole down the middle of the pipe but I'm probably telling you how to suck eggs.

John S.

JasonB, bsp is no where near to normal 7/16 much nearer to 7/8.

Peter

7/16" Is near to 1/4"BSP (but not quite), the thread number is the same. I have'nt been able to confirm it yet, but I seem to remember it as a gas thread, and I think the pipe size is the external size unlike water pipe, I'll have another dig and see what I find. Ian S C

Ian you are making the same mistake that I did. JS's tap is about 3/4 dia so that would be about right for a 7/16 ID pipe with 1/8" wall thickness.

J

J, oops, so it is very fine thread is'nt it, normal wouldbe about 11TPI. Ian S C

Well about right for BSP as 1/4" & 3/8" also use the 19tpi before it changes to 14 for 1/2"