Buck 3 jaw chuck out of whack

[Motorhead99999]

I recently acquired a leblond 14” lathe and finally got to play with it. I was going to make a new end mill holder for my mill until I clamped a piece of 2” steel in the lathe and spun it by hand and seen how far out it was.

With no work in the chuck and the chuck tight one of the three jaws is still loose because it doesn’t make contact with the other two by eye I’d say .150 thousands I don’t have a ton of experience with lathes but have never seen this before. It’s not a chuck that the jaws can come out of the top to off center work.

It it possible that the scroll is 180 degrees out on that jaw from someone taking the chuck apart to clean it? Should I make a grinder and grind the inner and outer edges of the chuck to re get things re centered?
Never been in this situation before.

I didn’t take a picture of the chuck last night but can take one tonight and post it.

 

[Philabuster]

Sounds like the jaws were not installed in the correct order in the chuck. There should be numbers 1,2,3 on the jaws that go into slots numbered 1,2,3.

Jaw 1 usually goes in first, then move the scroll to lock in jaw 2, then jaw 3.

 

[Tyrone Shoelaces]

As what Philabuster wrote but when you’re winding the scroll around take your time and be sure you don’t wind it too far. It’s surprising ly easy to do so if you aren’t paying attention properly. Everybody who has a three jaw must have done it at least once. I know I have.

Regards Tyrone.

 

[michiganbuck]

Here is a video showing

It may help to sharpie mark the jaws 123 so match how they are are factory marked.
Would not hurt to sharpie mark the chuck body123 as you intend to replace the jaws.(many chucks may have numbers or punch marks on that chuck body)

You might assemble 3 times if there are no body marks, varying the start slot (123) to see if there is one assembly that is best.

The most wear factor is how much the scroll can wiggle radially set place. brand new that amount is very little.

 

[michiganbuck]

Here is a chuck tear down, (may not be the same as a Buck chuck)

(X) The error here is that you should always mark the original assembly..Perhaps mark each piece with 12 0 CLOCK (Perhaps just set them on your bench 12:00 lined up.

You can see in the tear-down how the scroll is set in. if there is much over .002 wiggle a shim might be added to tighten it up.

Grinding on/in a lathe or chuck is the biggest culprit to chuck wear.. and the lack of cleaning and lack of lubrication.

 

[eKretz]

Pull the jaws as mentioned by the others. Reinstall while making sure the correct jaws are in the correct slots and on the initial rotation of the scroll for each jaw. Also have a good look at the teeth in the underside of the jaws. I've seen damaged jaws with a tooth broken off. If you have one of those, the jaw will be out of whack even if the jaws were installed in the normally correct places and order if they didn't wait a scroll rotation to put in the jaw with the missing tooth.

 

[lumley32]

it's not always the case that you have to install the jaws in the correct order, I have a set of jaws that have one tooth missing on one jaw, so you have to install them 3,1,2.

 

[eKretz]

it's not always the case that you have to install the jaws in the correct order, I have a set of jaws that have one tooth missing on one jaw, so you have to install them 3,1,2.

Didn't I just say that?

 

[lumley32]

Didn't I just say that?

must be an echo!

 

[Bill D]

If you take the chuck apart for cleaning grind or mill two small slots on opposite edges of the front and back body mating faces. This will allow a screw driver to quickly pop the body apart next time

 

[Tyrone Shoelaces]

Here is a chuck tear down, (may not be the same as a Buck chuck)

(X) The error here is that you should always mark the original assembly..Perhaps mark each piece with 12 0 CLOCK (Perhaps just set them on your bench 12:00 lined up.

You can see in the tear-down how the scroll is set in. if there is much over .002 wiggle a shim might be added to tighten it up.

Grinding on/in a lathe or chuck is the biggest culprit to chuck wear.. and the lack of cleaning and lack of lubrication.

No need to beat the shit out of the Chuck with a copper hammer. Just loosen the three fastening screws in the backing plate a few turns, put the Chuck on it’s side, hold on to the backing plate and tap the screw heads in turn with your copper hammer. That will separate the backing plate from the main body of the Chuck.

Regards Tyrone.

 

[RC Mech]

Worst case, line up the jaws scroll side up. It will be obvious which one goes in first, 2nd, 3rd.

Helping a buddy with an old lathe, his chuck jaws were stamped incorrectly. No broken teeth just mislabelled.

 

[Nmbmxer]

The 10" chuck on the lathe we have in the engineering shop had a ton of run out, couldn't figure out why. It seemed to be seated fine, OD and face ran true, but the work was always .015" out or so. After disassembling the chuck to inspect everything and finding nothing wrong ,I installed the back half of the direct mount D1-6 chuck and took .015" or so off the register between the front and back halves of the body. Reassembled and with the 6 body screws snug, tapped it true and then tightened it up.

It's run like that for years with .001 of runout across most of the scroll, if an intern crashes it we can easily true it up again. Not as sturdy as a set-tru with radial adjuster screws but if it moves 6x M10 mounting bolts then that's the least of its problem.

 

[4GSR]

The 10" chuck on the lathe we have in the engineering shop had a ton of run out, couldn't figure out why. It seemed to be seated fine, OD and face ran true, but the work was always .015" out or so. After disassembling the chuck to inspect everything and finding nothing wrong ,I installed the back half of the direct mount D1-6 chuck and took .015" or so off the register between the front and back halves of the body. Reassembled and with the 6 body screws snug, tapped it true and then tightened it up.

It's run like that for years with .001 of runout across most of the scroll, if an intern crashes it we can easily true it up again. Not as sturdy as a set-tru with radial adjuster screws but if it moves 6x M10 mounting bolts then that's the least of its problem.

Yeah, this is my standard procedure for my non-set true chucks in my shop.