Set Tru chuck for old lathe

I am looking for a 6" set tru 3 jaw scroll chuck for my South Bend Model O Heavy Nine lathe. I currently have a no name chuck that has quite a bit of run out and I have a Buck 6" 6 jaw set tru that I really love. I also would like to have the jaws removable so I can make some soft jaws. I see a few nice Bucks on Ebay from time to time, but really pricey. All the Bison brand set tru chucks I've seen are completely out of my price range as a home hobbyist. I have also heard that ToolMex or TMX makes a decent set tru chuck as well. I also don't really want to go to a 5" chuck because I need all the capacity I can get. Any ideas or are there other options for Set Tru scroll chucks out there?
Thanks

skipd1

How much are you willing to spend?

is 400 over budget?


you can make any front mount chuck into a set tru.


or here is your cheap option-

https://www.ebay.com/i/182484511092...0%26rvr_ts%3D2c8c8cee16a0ab199a87d77affab09e3

how do you turn a standard 3 jaw chuck into a set tru chuck??

OH, my...so many ways...simple "bump/tap true" for one.
my buddy drilled 4 holes into the rear face of a backplate and made a little "jacking tool" that had a pin that slipped in the hole with a t handle on the tool, insert tool,turn t handle and the end of the screw would push the chuck body...worked pretty darn good...hopefully my lacking explanation makes sense.


here is a horrible quickie drawing-




well, for some reason wont post right side up.

If you want a chuck for soft jaws, it doesn't need to be set-tru.

When you bore them in place, they are, by definition, concentric with the spindle.

Find yourself a chuck with 2-piece jaws missing the tops. They can go for cheap because a set of hard top jaws can cost a fortune.

Mine cost all of about $60.

Then get yourself some soft jaws from US Shop Tools.

Steve

I have a 6" Gator that I use as a sub-chuck in a turning center when I don't feel like boring softjaws. It has always repeated very well, even after bumping the hard jaws a couple of times with an OD tool. Has a 1.50" thru hole. You needed 3 different hex keys to center the chuck and flip the jaws which was annoying. Been nice to have used the same fastener size for the backplate and centering screws...

Nmbmxer said:

You needed 3 different hex keys to center the chuck and flip the jaws which was annoying. Been nice to have used the same fastener size for the backplate and centering screws...

Click to expand...

The Heavy 10 I operated in college was like that. One day when we were slow I put the chuck wrench in the mill and cut a hex stub on each end, one size for the chuck set-tru screws and one size for the compound rest grub screws.

Cole2534 said:

The Heavy 10 I operated in college was like that. One day when we were slow I put the chuck wrench in the mill and cut a hex stub on each end, one size for the chuck set-tru screws and one size for the compound rest grub screws.

Click to expand...

I dowel pinned and bolted a ring with 4 radial threaded holes to the back of a non set tru chuck,...now I have a set tru chuck. It's not rocket science, just do it.

I think trying to turn a "cheap" 3 -jaw into a very accurate "set-tru" type via the backplate is a mistake. Yes- you could possibly chuck up the work, indicate and adjust to less than a thou.

But I seriously doubt that if you chucked up another piece, especially one with a different diameter, that you would get the same result. Quality chucks cost what they do because of the precise machining and fit of the components, especially the scroll. And if you gotta indicate and adjust every time you chuck up a workpiece, might as well have saved the money and effort and use a 4-jaw.

No shortcuts here. I waited nearly a year (using collets and 4-jaws, because I couldnt justify a grand) until an absolute creampuff turned up on fleabay. Not a mark on it, when I received it and disassembled all surfaces still had original maching/ground surfaces.

Spend the coin, or work with collets and four jaw on second ops where precision is required and keep your eyes open for a deal. Mine had the wrong backplate, but that was easily rectified with a generic, new one for $75.

within the context of cheap simple lathes such as SB, it's hard to justify spending a lot on a chuck and it's surprising just how decent cheap 3 jaw chucks are nowadays...2 piece/soft jaws solve many problems.
now, a 4 jaw chuck is a different story- get the best you can,cheap 4 jaws suck and the first time you try to do an offset/eccentric and the damn thing won't hold straight....