Cleaning up BSW threads

If you really don't know the history (eg of Whitworth threads) please don't make it up.

Cheers, Tim

Or they could even be metric nuts that have been butchered or retapped or who knows after 70 years?

Edited By Hopper on 01/04/2021 11:46:05

Hi, just to show some difference between 1/2" Whitworth nuts and 1/2" UNC nuts, first photo from right to left, with the actual measurements across the flats are; Old Whitworth nut, new standard Whitworth nut and a standard UNC nut.

The next photo is with the nuts on corresponding bolts.

The next photo shows that both old Whitworth and new bolts and nuts are interchangeable and vice versa.

The next photo shows how far a UNC nut will go onto a Whitworth bolt and a Whitworth nut onto a UNC bolt, purely using figures and without undue force.

Lastly how far a UNC die nut will go on a Whitworth bolt and a Whitworth split die will go on a UNC bolt, again using figures and without undue force. It will be seen that a Whitworth split die will only engage the first thread of a UNC bolt but the UNC die nut will go almost halfway onto the Whitworth bolt.

Regards Nick.

Edited By Nicholas Farr on 01/04/2021 11:51:42

Thank you. I was concerned I'd got it wrong but all seems OK. The dies were a bit tight at first but nuts and studs work smoothly now. It is also quite noticeable that some of the studs are bent.

Yes the bending will certainly not help. If you have a split die like that one on the right in Nick's last picture, you can expand it slightly by screwing the clamping screw in the dieholder into the gap. This makes it less of a tight fit for the first run then if the nut is still tight, can be adjusted to suit to some extent. Good you got it sorted one way or the other after all that. Happy bandsawing.