It may be bad form to ask for a product recommendation here, but it's tough to do web searches for these things. Apologies if this question is out-of-line.

I just picked-up a 3-jaw 3-3/8" lathe chuck at a yard sale and it looks like it's in great shape. The problem is that it's got a 3/4x16tpi threaded hole and my lathe (a vintage 1950 Shopsmith 10ER) has a 5/8" plain spindle.

I don't seem to be able to find much in the way of spindle adapters with 3/4x16tpi outer threads, let alone with a 5/8 plain internal bore. Does such a beast exist? Or will I have to get two adapters:

  1. 5/8-plain to 1x8tpi
  2. 1x8tpi to 3/4x16tpi

That seems like a lot of hardware for a rather short spindle.

  • Something like this but with 3/4x16tpi on the outside instead of 1x8tpi. Dec 13 '16 at 21:54
  • 1
    Have you considered getting another spindle with the same taper as your existing one and just swapping them?
    – keshlam
    Dec 14 '16 at 3:14
  • You might also consider finding a local blacksmith (OK, fine, a machine shop) to inquire about having one made.
    – FreeMan
    Dec 14 '16 at 16:54
  • I've been told by a fairly reliable source that this item is actually a metal-working lathe chuck and not a woodworking one (though to my untrained eye, I can detect no reason why it would be), so I may actually sell this one and buy one that is more appropriate for my situation. Dec 14 '16 at 19:51

Not a true answer to your question, however you say that your lathe spindle is plain (I take to mean unthreaded). Any spindle adaptor would therefore need a grub screw or similar to secure it. It would not be a difficult task for someone with a metal lathe to produce an adaptor. My thought would be to use something like a drill arbour. You can certainly buy 2MT to ¾" 16tpi arbours, you would need to check the taper used on your lathe. To safely use with a chuck you would need one that takes a drawbar through the lathes headstock to secure in place. In a comment you said you had been told this is a metal working chuck, but didn't see the difference. The main give away is that it is three jaw - ideal for holding perfectly round bar stock, less ideal for softer and less round wood stock. Chuck's designed for wood tend to be of the four jaw scroll (self centering) variety, and tend to use a dovetail or grip jaw rather than the step jaws often found on engineering/metal chucks. Of course an engineering chuck is perfectly usable for wood turning, it just may not be as good at holding wood as a chuck specifically designed for the purpose ;-)

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