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Lathe chuck

I'm hoping some one knows about old Union Mfg Co. lathes chucks. I have a 6" one marked U-770 3 jaw scroll chuck.The jaws are also Union Mfg Co. with no.906 marked on them. No. 2 jaw has 2 teeth broken off of the scroll. Are these a special thread pitch to that chuck or can they be replaced , and can you get them from any place?
 
Ouch.

I have never replaced a scroll chuck jaw but I would be worried about runout when the jaws might not be a matched set.

Luckily a 6" chuck isn't huge, replacing the whole thing isn't too bad.

If it was a 12" or 14" chuck, the sticker shock would be worse.

I hope you find a good solution.
 
You are referring to the teeth inside the Chuck that engage the scroll? If so I'd say it's time for a replacement Chuck . Chances of finding one that is worn and ground exactly like yours is slim to none .
6" aren't that much , what the mount ?
 
You are referring to the teeth inside the Chuck that engage the scroll? If so I'd say it's time for a replacement Chuck . Chances of finding one that is worn and ground exactly like yours is slim to none .
6" aren't that much , what the mount ?
Yes, there the one's that engage the scroll .It's a screw on 11/2 x 8. on an old Monarch lathe.
 
Last I checked you could get a brand new Bison chuck for about the same money and machine it to fit your lathe perfectly (depending on the mount) with minimal run-out.

There are at least 3-4 ways to skin this cat so investigate.
 
For gunsmithing, I've found a 3-jaw is just about useless.
Very little if any first ops, which is the only use for one.

You're much better off with a 4-jaw. You can't indicate/dial in anything with a 3-jaw. I own one only because it came with the lathe, never used it.
 
^^^
I get that front mount three jaws can be tweaked with the mouting screws.
But short of boring the jaws for a specific diameter it's not going to be repeatable in my experience. Take the workpiece out and it's got to be re-indicated if put back in.
Which is why I own a Set-Tru's and not a 3-jaw scrolls, almost none of my machining is first ops.

JMO. YMMV.
 
I think buck calls their system adjust Tru. Bison calls it set Tru, lol. I got a Bison and it repeats. Pratt has another name for it...

I got several sets of soft jaws for it as well.
 
I think buck calls their system adjust Tru. Bison calls it set Tru, lol. I got a Bison and it repeats. Pratt has another name for it...

I got several sets of soft jaws for it as well.
I got both- one is a 3 jaw one is 6. Youre correct the bison says set tru right on the face engraved about 1/8” deep. I call em all set tru since that was my first!
 

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