02-01-2021, 04:20 PM
I found my copy of the book today. As it is quite old it does not cover the "modern" 17/50 model. The 1750 is a 10mm lathe and I think of it as a clockmaker's rather than a watchmaker's lathe. The Pultra 10mm collets listed have a thread 0.389" diam and 1.0mm pitch. I am guessing that it is the drawbar which you need, which is internally threaded to screw onto the end of the collet and draws the collet into the headstock. I am attaching a photo of my watchmakers lathe drawbar and a collet.
My solution would be to make a drawbar and to use a scrap collet to make the necessary tap. As it is probably not going to be heavily used, the drawbar could be made from brass rod. The collets are hardened and would probably cut steel if the flutes were reasonably ground but just grinding three eqally spaced slots using a Dremel type tool would be adequate for cutting brass. I am quite happy to give any further advice as I have spent a good deal of my working being paid to make swarf!
Rod
My solution would be to make a drawbar and to use a scrap collet to make the necessary tap. As it is probably not going to be heavily used, the drawbar could be made from brass rod. The collets are hardened and would probably cut steel if the flutes were reasonably ground but just grinding three eqally spaced slots using a Dremel type tool would be adequate for cutting brass. I am quite happy to give any further advice as I have spent a good deal of my working being paid to make swarf!
Rod
