13/16 26tpi die nut and tap

As you wish to restore your threads, have you considered a thread file?

If you are unable to borrow one, Hitchcocks Motorcycles sell this one:

https://accessories.hitchcocksmotorcycles.com/accessory-shop/tools-chassis/14114

Says 26TPI on their page, but have seen Sykes Picavant files advertised elsewhere missing 26tpi from the sizes covered so best to check with them first. That said, Enfield are/were traditional with their singles up to now so they ought to be right.

Regards,

George.

I had the same problem and finished  up buying a new nut from NOC parts and a 26tpi  thread file from E bay. I had not used a thread file before but was surprised how well it worked Bryon

If its the first thread or 2 that's distorted on the yoke shaft then the thread file will do a better job than the die. The die will follow the distorted threads until it engages with a few of the good threads, in the time it takes for this to happen it will narrow the first couple of good threads. When you use the thread file engage with more good than bad threads so the bad become good. Once the yoke shaft is good then try the nut as it may not be too bad. A thread file will not work on an internal thread but a smaller tap but 26 tpi can be used as an internal thread file, 1/4 BSF is a good one to use, 26 tpi and small enough. 

The Sykes-Pickavant file mentioned by George is not as good as my decades old Metric and Unified ones. It can do the job but don't have the right feeling. It might be caused by the different angle on BSW/BSf (55 degrees) compared to the cycle thread (60 degrees).

.. careful use of a three-square (triangular) file can often get male threads back into usable condition. The angle is of course 60 degrees.

I have a two-into-one issue with a couple of tachometer gearboxes, both of which are faulty in different ways but with which I hope to perform the two-into-one trick in order to obtain a functioning item.  As the attached photo shows, one unit is missing an end cap and one of its pinions, whilst the other one is complete but the thread for the drive cable spigot has been stripped, so I would like to swap over the two cases.  The job should be easy apart from the task of popping out the boxes' circular end-caps, which are an interference fit in their casings, which are cast from Mazak or a similar alloy with a high zinc content.

I would welcome any tips from anyone who has already tackled this sort of chore successfully.

Ian.

(North-East Yorkshire)

Ian, you need to start a new full topic, your current post will only be seen by cycle thread enthusiasts and miss the tacho experts. 

.......reforms 26tpi threads. Don't know where you would find one these days.

There is a cheaper version of that but it only does one size and being soft not hardened steel will not do as good a job. Take a good correct nut and cut into halves. Place the 2 halves on a good part of the shaft and then use a ring spanner to keep the 2 halves together and using the ring spanner turn the split nut so it runs over the distorted threads.