Lathe Chuck Mystery

[jwmay]

The inner hard jaws obviously came from another chuck as they were marked 1, 3 and 5, with the #3 being in the 2nd jaw slot and the #5 in the 3rd jaw slot, so I'm assuming they came from a 6-jaw chuck.

I'm not focusing much on the fix, as much as how it could be possible that both sets of jaws could be dialed in while the body is offset from the back plate.

Haven’t you answered your own question by stating plainly that these jaws aren’t even made for this chuck?

Stating your question with all information would look like this: How is it possible that jaws from a different chuck don’t run true to this one?

 

[G-ManBart]

Haven’t you answered your own question by stating plainly that these jaws aren’t even made for this chuck?

Stating your question with all information would look like this: How is it possible that jaws from a different chuck don’t run true to this one?

No, not really.

One set of jaws is from a different chuck so it makes sense it took a lot of adjustment to get them zeroed. If I change nothing else, and swap in the outer jaws that are marked 1,2,3 (so clearly not from the 6-jaw the inner jaws came from) they are also zeroed.

If the chuck body is moved to zero the jaws from the 6-jaw when I swap in the original outer jaws they shouldn't be anywhere near zero.

I guess it's possible somebody zeroed the chuck with the inner jaws, then installed the outer jaws and ground them in place, but that seems unlikely. The outer sections of the outer jaws didn't appear to have been ground, but I don't recall what the innermost section looks like...I'll have to look again.

It was on a Buck D1-6 back plate when I got it, so it was being used on the lathe the way it was.

 

[FOMOGO]

Looks like the jaw on the right (inner set) needs the tip to be narrowed to center properly. That could possibly account for the imbalance, at least with that set of jaws. Mike

 

[G-ManBart]

Looks like the jaw on the right (inner set) needs the tip to be narrowed to center properly. That could possibly account for the imbalance, at least with that set of jaws. Mike

I think what you're seeing is just an angle/shadow since the phone wasn't exactly square to the chuck...hard to say. The jaws had a trace of bell mouth to them, so that could be some if it.

The bigger question is just how it's possible to have a set of jaws from another chuck and a set of jaws from this chuck that are both zeroed while the body of the chuck is significantly offset from the back plate. I just don't see how that can be possible barring something really unusual or a huge coincidence.

 

[jwmay]

I think it’s possible that NONE of those jaws go with that chuck. Every three jaw chuck has 1,2, and 3 labeled. And the fact that it was on a backplate means nothing as to whether or not it was in use.
The fact that they are similarly incorrect is as likely to be coincidental as anything else.
The assumption that something odd was done to those jaws or that chuck prior to you owning them is equally likely. As you yourself are pondering the very same sort of effort.
Anyhow, you seem to be sure of your position, and have the best view of it. Good luck! lol

But certainly you can imagine a scenario where bubba grabs the wrong jaws and installs them, they don’t work out, he takes the chuck off, and it sits unused until auction day. Every shop Ive ever seen has piles of questionable tooling that has “something wrong with it”, but doesn’t get thrown away.

 

[G-ManBart]

I think it’s possible that NONE of those jaws go with that chuck. Every three jaw chuck has 1,2, and 3 labeled. And the fact that it was on a backplate means nothing as to whether or not it was in use.
The fact that they are similarly incorrect is as likely to be coincidental as anything else.
The assumption that something odd was done to those jaws or that chuck prior to you owning them is equally likely. As you yourself are pondering the very same sort of effort.
Anyhow, you seem to be sure of your position, and have the best view of it. Good luck! lol

But certainly you can imagine a scenario where bubba grabs the wrong jaws and installs them, they don’t work out, he takes the chuck off, and it sits unused until auction day. Every shop Ive ever seen has piles of questionable tooling that has “something wrong with it”, but doesn’t get thrown away.

It is certainly possible that none of the jaws go with the chuck, but it seems like a giant coincidence the two sets of jaws just happen to zero out the same when one is definitely mismatched.

I can't prove the chuck was in use, but going off what I saw, I think it's likely. The lathe was a Clausing-Colchester 15" (D1-6 spindle) with a 6-jaw chuck mounted. On the cart next to it was this 3-jaw as a separate lot, there was a 12" 4-jaw as another lot and then the tool post/holders as another lot. They also had a 13" Clausing with a D1-3 spindle that was set up the same....6-jaw mounted, 3-jaw, 4-jaw and tool post/holders as separate lots. Both of the mounted 6-jaws were master/top jaws, so not a donor for the inner jaws on my chuck.

I wouldn't say I'm sure of my position...it's just a theoretical discussion about what could have happened. I could sell the back plate, break even and not be out a penny so I'm not at all worried. It'd be nice to make the chuck useful again, so before I start grinding on something I figured it's worth kicking around what could have happened in case that would suggest a better path.

 

[jwmay]

but it seems like a giant coincidence the two sets of jaws just happen to zero out the same when one is definitely mismatched.

Yeah true. I thought I read you talking about taking it to someone, and spending $600 to have it repaired, and how that would be a good deal. Which is where I started pressing the panic button. Lol

I’m not sure why I care how you spend your money, but that seemed a little extra for a chuck with a name on it. lol

My most expensive chuck was 225 from Enco before they consolidated with MSC. But it’s silly to expect your limit to be the same as mine or anyone’s. $600 may actually be a good deal. Idk.

 

[G-ManBart]

Yeah true. I thought I read you talking about taking it to someone, and spending $600 to have it repaired, and how that would be a good deal. Which is where I started pressing the panic button. Lol

I’m not sure why I care how you spend your money, but that seemed a little extra for a chuck with a name on it. lol

My most expensive chuck was 225 from Enco before they consolidated with MSC. But it’s silly to expect your limit to be the same as mine or anyone’s. $600 may actually be a good deal. Idk.

I'm going to check with the folks at Kalamazoo Chuck Manufacturing to see what they would charge to fit a new set of inner jaws to the chuck since it appears otherwise sound, but I'm not in any rush. I actually bought a San Ou 3-jaw adjustable chuck that matches the dimensions of the Buck so it'll work with the existing back plate. It's got master, reversible jaws and was $229 out the door. I've had good luck with their chucks in the past, so hopefully that will continue.

Comparable new chucks from Buck, Bison and Pratt Burnered are all in the $1,200 - $1,500 range give or take and I think the Buck is actually made in China. I figured if I could get a set of jaws made for the Buck for something like $3-400 I'd be under $500 total...not too terrible.

 

[Cadillac]

That last picture of the chuck on your lathe shows something. The lower jaw at 6 o’clock looks different then the 10&2 jaw. It looked like the stepping on the back was different than the others and the coloring was different.

 

[Cadillac]

Went back and looked again. I would have to agree those jaws are not for that chuck for sure. They do not nest properly. When you close a chuck all three faces on the jaws will touch each other eventually. Yours jaws are shaped with a narrower V let’s say. Which would be needed on a 6 jaw with more jaws.