I thought I would address the shortcomings of the old style threaded lathe spindle. All of the chucks which are used with the Smart & Brown model A have backplates using a 1 3/4"W thread, and I decided to investigate the possibility of using some type of drawbar. Only one chuck looked to be a likely candidate, there was a space between the backplate and the rear of the chuck. Also the backplate overhung the end of the spindle by about 3/16". With a boring bar, I produced a recess in the backplate 2" diameter stopping about 0.02" short of the spindle and made a steel disc with a 3/4" hole to fit inside the chuck assembly.
I used a large rod with nuts at either end which had been laying in the metal junk/stock for years which was exactly the right length. It had a strange thread on it which was found eventually to be 1.5mm pitch. The right hand nut was turned top hat shape to fit in the disc and a bush for the left end was made to keep the drawbar central. The bar even had spanner flats on one end, I'm so glad I hadn't cut it up for another job.
Of course, you loose the hollow spindle although the S&B only has a 15/16" bore anyway.
I used a large rod with nuts at either end which had been laying in the metal junk/stock for years which was exactly the right length. It had a strange thread on it which was found eventually to be 1.5mm pitch. The right hand nut was turned top hat shape to fit in the disc and a bush for the left end was made to keep the drawbar central. The bar even had spanner flats on one end, I'm so glad I hadn't cut it up for another job.
Of course, you loose the hollow spindle although the S&B only has a 15/16" bore anyway.
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