My 1946 TH42 came with an Atlas 5" 3-jaw chuck, IIRC. It's FUBAR, and awaiting time for me to try out one of my tool post grinders on it... If it's a real Pratt it should be a very good quality chuck, but it may be old and worn, as is my Atlas chuck. Give it a good deep cleaning, and see if that helps any. Some folks bought complete sets, some got just the lathe, so there's no telling what came with it unless you got original paperwork with it. Mine was at least second hand, and maybe more.? And don't expect too much from a 3-jaw chuck. A 3-jaw self-centering chuck that has a TIR of .003" is considered pretty good. And they're not used for things that require high precision. Usual tolerance for most machining is +/- .005" in industry, according to the instructor in my machine shop class a few years ago.?

This isn't something taught in my class, but learned from some of the old books. If you want the absolute best precision a lathe is capable of, you need to turn between centers. Next best would be either a 4-jaw independent jaw chuck, or a collet chuck. Or collets that fit the spindle. ;) An ER32 or ER40 chuck can be had to fit the Atlas/Craftsman spindles, and they will allow material up to about 3/4" through the spindle. I also found an ER32 collet chuck and made an adjustable mount for it. Since I also have a set of ER32 collets I bought for that mini-lathe.?Morse Taper 3 (MT3) collets fit the spindle with no adapters, but they do need a draw bar to keep them from spinning in the spindle. That is a bad thing! The draw bar also prevents material from going through the spindle. Atlas/Craftsman and the 7x mini-lathes use an MT3 spindle, and an MT2 tailstock taper, so a lot of the accessories for one can be used on the other. With a new back plate, you can use the 3 & 4-jaw chucks on either, too.?When I got my Atlas lathe, first thing I bought it was a 6" 4-jaw import chuck. Could not afford any of the really good chucks. A Buck Adjust-Tru was more than I spent buying the lathe. But you can make your own back plate and turn about any chuck into an adjustable chuck. With just a little fiddling, I can get a part dialed in to .0005" and with a bit more, I can get to .0001" in the 4-jaw. I'm not doing rocket science, but wanted to be able to.?

I probably have much more stuff than I need, but you don't have to go bonkers like I did. :)

Bill in OKC