I picked up a genuine Hercus 3C collet set at the Bendigo swap meet last weekend. A nice complete set with the storage stand and all. After cleaning it up I have found the thread in the collet end of the draw bar to be in poor condition. Probably not so unusual. I thought I might make a new one. A bit of research suggested the internal thread (collet end) is an odd thread of 0.635" x 26TPI, so that will have to be cut in the lathe. The external thread at the other end is 3/4" x 24TPI, which I can get a die for, but will probably also cut that on the lathe (maybe use the die to tidy it up).
Anyway, my question: can someone direct me to a supplier of the tube stock?
The tube is a thick walled tube, or hollow bar, 19mm OD and 13.75mm ID. This gives a wall thickness of 2.6mm in round numbers. Getting 19mm OD tube is OK, but the thickest wall tube I can find is 1.6mm - which is just too small for the internal thread (and leaves a pretty thin wall on the external thread). I believe the original tube was mild steel.
I'm in Melbourne. Happy to buy a longer length if need be (maybe make a few tubes for others, or just cut off a length if someone else wants to share the 'experience').
You may also have some alternative/better suggestions to solve my problem.
Thanks in advance, Tony.
PS. the internal thread of 0.635" x 26TPI is mighty close to 5/8 x 26TPI BSB (for which taps are available), but not quite. Some research suggests a tap of this size may end up with some very tight collets.