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4 jaw chuck help.

Brian Ski

Aug 8, 2019
I have a 9" South Bend lathe. Wanting to add to it an independent 4 jaw chuck. I am the newbie to machining. I know I need a 2-1/4" 8 thread. I would prefer a cheaper used chuck. I am surly not someone who is a precision machinist. Just wanting to do some learning. Doing some internet digging I have heard a 6" is a good size for a chuck. How large of a diameter would that hold? Is Ebay the best place so far for used chucks? I can't seem to find anything local. I am not in a hurry either.

Any advice? I know the best quality is always better, but I have limited talent and money.

Edit for correct thread size.
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eBay is a good option, four jaw chucks are the most universal of all chucks and usually fairly inexpensive, at least compared to the cost of all of the other tools you'll soon want to add to your collection.

As far as capacity, that all depends on how you hold the part, and WHAT the part IS!

A box fan blade has a 1/4" shaft and 18" blades. You only chuck the shaft.... Usually.

Get whatever you can afford, work up from there.
Be aware that if the jaws of a used chuck are loose in the body ,the chuck is worn and near worthless.......Dont believe the old sellers lie "just regrind the jaws ,good as new"
Be careful with used chucks. My Southbends (9a and Junior) both seem to have tight spindle threads to the point that I can't get my good used chucks on all the way. However, the same chucks fit my Taiwan lathe just fine.
6" seems a reasonable size for a 9" lathe. Capacity depends on jaw orientation, condition, and the part. The jaws can't extend too much past the body and still be safe.

If you ebay it, just be sure the pics look really good. Be patient and wait for a nice looking one. Be sure you can return it. Return shipping shouldn't be horrible for a 6".

I ebayed an 8" once. The screw threads were cracked off to the danger point on some of the jaws and the screws. I talked the seller into paying for return shipping,. He was clueless about things machining and wasn't happy about it. I hope he threw it away.
A 4jaw independent can have wobble, that is when you indicate dead zero at one place the part will run out indicating an inch away.

It looks like minimum quality chucks are about $200 and up with top chucks in the thousands..
A good chuck makes the lathe much more enjoyable.
Well at least I looked... In the back of my mind something did not seem right. So I looked before ordering. I have the larger 2-1/4" thread not the 1-1/2". I think I have only removed the chuck once. BTW I do know not to use the back gear to remove the chuck. I bought a strap wrench for it. Looks like the teeth on the back gear have been repaired before.

I am still pondering a 6" or 8" chuck.

I do have a large tube I would like to turn, but it is too big for this lathe (I think about an 11 inch diameter).

Thanks for the help.
What 9" lathe do ya have that takes a 2 1/4 x 8 thread ? I have a Sanou 6" with 2 piece jaws on my 9A .
If your looking for a new chuck the Sanou chucks are good chucks . I have 2 , 1 with 2 piece jaws & one without .I would buy another when it comes chuck time again. I got mine from one of these guys


these guys are 9 bucks apart for a plain back chuck . You will need a backplate unless ya have one . Ya can order one with the backplate or without from CME , ya will still have to do some machining for proper fit , which is something ya would have to do rom any vendor .

Animal12? Are you on the Burke forum?

I am an amateur when it comes to machining. I have a South Bend Lathe 10" (edited for 10") They are in 2 thread sizes and glad I checked. one is 1-1/2 8 and the other is 2-1/4 8. Mine has a long tube that fits through the spindle so you can draw collets in with the larger thread. It came with a bunch of older tooling, collets and a 3 jaw chuck. Looking to expand.

That company you posted has some good prices. They show on sale. Still undecided if I want to do a 6 or 8" chuck. Leaning toward an 8". I will need a backing plate too. They say that they need machining to finish. Do you know if they mean the outer rim? Or the face?
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I don't think any SB 9" swing lathes had a spindle nose bigger than 1-1/2 x 8tpi. Sounds like you have a Heavy 10 (10L) or larger
It has a short bed on it. Remember I am the rookie guy... Ugh 10 right on the QC gear box. How did I miss that?? Rookie thing I guess.
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I think I will go with an 8" chuck unless someone has reasons not to.

Animal, thanks for the tips on those websites. Strange one has a great deal on the chuck, the other has a great deal on the backing plate.
hey, you figured out the size and thread of the spindle, that's what matters! Personally, I think a 6" and an 8" would be ideal for a 10" lathe. 6"ers are way easier to move around and thread onto a spindle than an 8" chuck, even a 4 jaw. But sometimes you just need the size.
I use a 6" 3-jaw and 8" 4-jaw. Seems to work out well. You might get lucky on a used 4-jaw in terms of wear because everybody is lazy and hates 4-jaw chucks, using the 3-jaw if they can possibly get away with it. I don't know about the larger spindle size, but the smaller ones vary a bit by manufacturer. You might do a search and see if SB tends tight or loose.
Have ya had any issues with the 8" as far as size on the lathe ? I need to get a larger 4 jaw for my 9A & have been dragin my feet cause I can't make up my mind on size .
One of the most critical issues is RPM. If you run small parts you want hi RPM and cheap cast iron chucks are not rated for it. A chuck that is over speed can come apart!!! Semi steel is often seen in chuck composition. It will stand more Rs
Check the rating before you buy.