Threading a punch tube

[TomE]

I purchased a couple of replacement tubes for an Osborne #153 spring punch, and one of them doesn't screw into the punch.  The threads appear to be shallow and incompletely cut.  I received a replacement tube with the same problem.  While waiting for the vendor to resolve this with CS Osborne, I tried cutting threads on one of the tubes and the metal is hard and brittle (which I'll view as a good thing).  Any advice about removing the temper, cutting threads, and hardening the tube would be appreciated.  I don't own a forge but have an acetylene torch, oven, Zippo lighter, ....  This is an experiment while waiting for Osborne to replace the defective tubes.

[fredk]

I'd try using a fine tri-square file to chase the threads first

[zuludog]

7 minutes ago, fredk said:

I'd try using a fine tri-square file to chase the threads first

Or a knife blade needle file

[chuck123wapati]

if its thin and small enough a soldering torch will heat it enough, the acetylene is plenty also, anneal it cut the threads then reharden bright orange into oil  and temper at about 400 f. the hard part is getting it into the oil at bright orange you only have a second or so. temper it in an oven or toaster oven

here is a video the operation is the same

 

Edited December 24, 2021 by chuck123wapati

[TomE]

Thanks @chuck123wapati!  I'll watch the video after I feed some horses and report back on my results.

[bruce johnson]

If this is an old frame - The old frames were tapped with a shallower tap and the new threads on the replacement tubes are the correct pitch but too high. Chase the threads in the  frame with a new tap of the same size and you will be good without doing anything else. realize they used three sizes of taps - 00-7 used the same, #8 had it's own size, and #9 and #10 had a different one. 

I chase the threads in every single tube punch I do so down the line the new replacement tubes will fit. 

[MikeRock]

Bruce,

Thank you for that.  I had the same problem and recut the threads, a real pain. 

Merry CHRISTmas to all.

Mike and Valerie

 

 

[TomE]

19 hours ago, bruce johnson said:

If this is an old frame - The old frames were tapped with a shallower tap and the new threads on the replacement tubes are the correct pitch but too high. Chase the threads in the  frame with a new tap of the same size and you will be good without doing anything else. realize they used three sizes of taps - 00-7 used the same, #8 had it's own size, and #9 and #10 had a different one. 

I chase the threads in every single tube punch I do so down the line the new replacement tubes will fit. 

Thanks, Bruce.  Good information.  My spring punch is about 5-6 years old, and the 00 replacement tube fit whereas the 0 tube in the same order had shallow threads.  Following advice from @chuck123wapati I annealed the tube, cut in the threads with a 5/16-24 die, hardened and tempered the tube, then cleaned up the cutting edge and polished it.  I had to punch some oiled leather to clean out the exit hole and now I have a working punch.  Thanks to everyone for their input.  It is a privilege to connect with so many experienced leatherworkers here. 

[MikeRock]

If you stick the punch in a potato and heat the threads to orange quickly a few or three times, just the threads will soften and no hardening and tempering is needed.

[TomE]

7 hours ago, MikeRock said:

If you stick the punch in a potato and heat the threads to orange quickly a few or three times, just the threads will soften and no hardening and tempering is needed.

Good tip!  I'll try the potato for the replacement tube that has the same problem with shallow threads.