3/4 Whitworth Tap and Die?

J

john_morris_uk

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Has anyone in the Plymouth area got a 3/4 Whitworth tap and die I could borrow for an hour or two please? I am having trouble finding a hire shop or anywhere to borrow these tools, and its a bit pricy to buy them to chase one thread thats a bit tight. And yes, it is definately 3/4 Whit before anyone asks...
 
A bodgers technique if you can't get the die, and depending on how bad the thread is. Works best on brass/bronze male thread. Get a steel nut of the right thread. Cut a slit in one face all the way through thus making a form of die. Check it will run on the thread at all. Assuming it will, run it up and down the thread compressing it in Mole grips and it will act as a form tool. Its a bodge but works surprisingly well.

If you have a steel male thread and its quite bad I'd suggest a little pre dressing with a needle file.

Female thread is far more difficult and by the time you have knocked up a bodge tool you might just as well have got the proper thing, you would need a steel bolt, slt it up the middle, clean all the burrs off the cut sides with a needle file and then set it out using some shim brass, the idea being that you have a slit wither side with the shim as a core. The slit makes a form tool and the core prevents the bolt compressing below nominal diameter.

I would lay reasonable odds that the tools exist somewhere in Devonport Dockyard for a suitable "tot".
 
You might try going to Knights at Mutton Cove, they do loads of ex dockyard stuff and have lots of taps and dies. You might even pick up some other goodies. I think they are open sat morns.
 
Most older engineering workshops and fabricators have a supply of old stuff like that in a drawer. I got hold of a special huge box spanner for a couple of quid fee to do a one off job last year.
 
If you end up having to buy one, Tracy Tools Ltd, Dartmouth 01803 833134, are a cheap source. Or Leeside Toolshop, Yapton, Sussex 01243 554056 sell masses of secondhand tools and may do mail order.
 
Thanks for the tips gentlemen.

I found a 3/4 whitworth bolt in the fastening shop I usually use on Exeter St Plymouth, which showed me that the nut was perfect. ie it was the propshaft thread that was binding.

A combination of filing and grinding paste got the 'new' nut to fit. It was one of those things, where the old nut and the new nut would fit perfectly on a new 3/4 whit thread, but only the old nut would fit on the propshaft thread.

By the way, Woods of Crediton have moved to a new premises, and now I can't find anything when I go there!

The dockyard would have helped for the usual packet of biscuits, but I was not confident of getting hold of anyone on a Saturday.... (I don't think my propshaft nut problem allows me to call out the emergency engineering teams...) I am currently working away from Plymouth during the week, and its a lot more difficult to get the odd jobs done - hence my plea on the forum.

Thanks again.
 
John
I'm glad you fixed it - I was going to suggest buying a "thread file" these are files that have a teeth shaped file - normally there are 4 different thread forms on each file but they are only any use on external or male threads.

Peter.
 
Both 3/4 whit and 3/4 unc have the same pitch at 10 tpi but the depth of the thread and angle are a bit different. My bet is that you actually have 3/4 unc shaft and the new whit nut wont fit well because the thread is deeper.
 
I thought of that - and thats why I checked both the old and new nut on a brand new 3/5 whitworth bolt. From memory whitworth threads have 55 degrees between faces of the thread and the top and bottom of the threads are rounded.

However I am still not sure why the thread was binding with the new nut.
 
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