6 jaw chuck holds work way off center

[Seuss54]

I recently acquired a South Bend Lathe and it came with a 4 and 6 jaw chuck. The lathe needed some cleaning and I wanted to take it apart and get a good look at some of the internals before I started running it and this past week I finally got it up and running. The 6 jaw chuck was already threaded on the spindle so I threw a piece of steel I got into the chuck to start making chips and as it's spinning the piece looks awfully strange to me. I go to touch of the piece and make a few really light cuts and the darn thing is like 100 thousandths off center. I pulled it off and pulled all the teeth out and put them back in, thankfully they are stamped 1-6 as well as the slots they were in but that fixed nothing.

I got the recommendation to use a boring bar to actually bore the teeth out to be centered up again but is this possible? It's an old chuck I have no idea what the jaws are made of.

 

[GeneT45]

First thing to check is to see if the chuck is a "set-tru" type. Usually that means some allen head or square sockets, usually smaller than the regular chuck key, that can be used to center the work to near perfection. It's hard to imagine a chuck being out 0.1" and not showing some serious damage, so I suspect it was adjusted for some eccentric turning.

Pics of the chuck, particularly around the sides, might be helpful.

GsT

 

[Seuss54]

Of course, im guessing that's what these are for. Forgive my stupidity I am still very much a beginner and bumbling my way through all this.

 

[projectnut]

Also make sure the jaws are in the proper slots. Each jaw should have a number stamped into it and each slot should have a number stamped along side of it

 

[markba633csi]

Yep it looks like a set-tru so you need to true it up. Re-machining the jaws is not a job for a beginner so don't go there.

 

[mmcmdl]

Remove the jaws and re-install them #1 first . The jaws have to installed in order and have to go into the scroll correctly . If that chuck is off .100 something is not correct as a set true can't be thrown off that far .

Take a pic with the jaws fully closed and post it here if you would .

Edit . After looking at the above pic , definately looks like the jaws are installed incorrectly . Looks like the top and top right jaws are out past the OD while the others are not .

 

[GeneT45]

Of course, im guessing that's what these are for. Forgive my stupidity I am still very much a beginner and bumbling my way through all this.

Nothing stupid about being a beginner, none of us were born knowing this stuff. That said, I think mmcmdl probably hit the nail on the head - I hadn't even thought of that.

GsT

 

[mmcmdl]

Nothing stupid about being a beginner, none of us were born knowing this stuff. That said, I think mmcmdl probably hit the nail on the head - I hadn't even thought of that.

One of my signs on the wall read " If I can't fix it or mess it up , you don't pay " .














I haven't had a paying customer in 48 years .

 

[VicHobbyGuy]

I'm a beginner and I didn't understand how to install jaws in a scroll chuck until I watched this video by 'MrPete' - watching for that 'first tooth' -the beginning of the scroll - to show up before inserting each jaw was the key. You can skip to the 3-minute mark:

 

[Uglydog]

Of course, im guessing that's what these are for. Forgive my stupidity I am still very much a beginner and bumbling my way through all this.

Seuss54,
It's good and appropriate to be a "beginner".
It's ok to bumble.
It's ok to fail.
It's ok to be wildly successful (precise and accurate).
It's also necessary to have great fun, be very safe, and fiscally accountable to your family as you begin and progress.

Daryl
MN