Oh Fu.uudge! Dropped my 4jaw chuck

[lynnl]

Was switching from the 3jaw to 4 jaw and after removing the 3jaw was having difficulty holding the 4jaw up so I could screw it on (8" chuck, arthritic hands).
I was in the process of finding another thin board to put under it to raise it more in line with the spindle. I'd positioned it so I thought it wouldn't roll, and even stopped to observe for a few seconds to make sure. But a few seconds after my back was turned I heard the crash as it fell on the concrete floor.

It now has a crescent shaped crack on the back rim about 1.5 to 2" long, maybe 3/4" wide. The piece is still rigidly in place, but I can see the trace of the crack on the backside. Tho I can't feel it back there.

This is a Horton chuck, old - but I don't know how old. I can't tell if it's cast iron or that semi-steel. I suspect the latter.

I don't want to try to trust it to my welding skills, such as they are, so I'll probably take it to a professional shop and see if they can TIG it.

This is on a 13" LeBlond with a max speed of 500 rpm. It might hold as it is, but I'm leary of the potential for that chunk to fly out and disappear up my nose.

Any suggestions or comments? ...other than "you dumass!" I already know that!

[ckelloug]

I'd offer to help with my tig welder since I'm down the street but I'm out of argon and tig about as well as a rabid weasal. I did manage to get my four jaw on last week after a fight with some asian bolts if you're desperate.

[Carld]

it was just waiting for you to turn your back. You could have watched it for an hour and when you turned around, KABAM.

Back rim??? does that mean it fell on the threaded hub and the crack is an arc in line with the circumference?

[jcarter]

Can we see a pic of it?

[gnm109]

Good Lord! I'm glad it missed your feet. That would put you away for a while. That's why I hate to change chucks even though I have the D1-4 system. It's always a pain and it's getting harder every year.

I'd take it somewhere and have it welded. It will be fine.

Glad you weren't hurt!

[Evan]

You need to make yourself a chuck stick. Hardwood from an old shovel or whatever works well.

[lynnl]

it was just waiting for you to turn your back. You could have watched it for an hour and when you turned around, KABAM.

Back rim??? does that mean it fell on the threaded hub and the crack is an arc in line with the circumference?

No it didn't hit on the back plate.

Basically it landed on the periphery of the chuck body, but the back side of the periphery hit first. i.e. the jaw side was slightly higher.
Looking at the back side of the chuck, it's solid in the four areas where the pinions are, but sort of hollowed out in the areas between. That is to say the back of the chuck body is webbed, with the pinions in the four webs. So the chuck periphery over those hollowed out areas is only about 3/8" or so thick. It's noticeably lighter than my 8" 3 jaw because of those hollowed portions.
I think if it had landed on, or closer to one of the pinions it would've sustained no damage.

After looking closer, the crescent shaped crack does not extend all the way at one of its ends. I've wrapped 4 layers of industrial strength duct tape around the chuck over the cracked area, which should tend to preclude it breaking loose further, or at least briefly contain the shrapnel if it should fly loose.

From the looks of it, I'd say the odds of it coming loose are probably no more than 5-10%. But I do want to get it fixed.

Yeah that's what I did (after the fact) Evan.

I've always thought about making a cradle, with radius to match the chucks, to support the things when changing. Maybe even include a couple of pairs of ball bearings to permit screwing it on while fully supported. I may give that more serious thought now.

[tattoomike68]

A cracked chuck says" I will hit you in the face with 20+ pounds at 60 MPH"

send it to the foundry gods or use it on a rotary table where its doing low RPMs.

you can weld it up and use it for low rpm work, I tend to machine faster when using a 4 jaw but that chuck is no longer safe.

[MickeyD]

I have never seen any cracks get better but I have seen a lot get worse quickly. I think what you have now is a very valuable positioning jig. This can make welding and brazing easier, assembling things simpler, and tons of other uses. Just be glad that it did not crush your foot or some other body part you might be interested in keeping.

[Evan]

I agree that it shouldn't be returned to service on the lathe. For the crack you can prevent it from going further by stop drilling it with perhaps a 1/8" hole about a 1/4" beyond the furthest perceptible part of the crack. That provides a radius to spread the forces in the end of the crack so it won't propagate.

[winchman]

Evan,

Why don't you snug the chuck stick in the jaws before removing the chuck from the spindle so the chuck will be centered on the threads when you put it on? Just leave the stick in the chuck.

What's the pattern on the right end of the stick?

Roger

[Evan]

Why don't you snug the chuck stick in the jaws before removing the chuck from the spindle so the chuck will be centered on the threads when you put it on? Just leave the stick in the chuck.

Because I didn't think of it.

The pattern is for more grip. My hands don't work well (nor does any other part). I get momentary spikes of pain that are entirely unpredictable and cause me to drop things frequently.

[BobC]

[QUOTE=Evan]You need to make yourself a chuck stick. Hardwood from an old shovel or whatever works well.
QUOTE]

Nice idea. I will do it.
Thanks,
Bob

[hardtail]

lynnl if you drill the crack as suggested and weld it up and only you ever use it, I'm sure you could get by with low rpm work, the trouble is for it never to be sold or used by someone else.......it will likely be slightly out of balance anyway for speedy manouvers

I pulled a shyhook/toolpost crane out of the dumpster a couple weeks ago and it's doubtful I will ever use it as I'm going to fab up a monorail system out of unistrut but it's yours if YOU want it, the shipping would probably be a killer though........frown

[thistle]

I would not use the chuck on the lathe any more.

HSM or MW magazines have had a few gadgets in the past
to help with chuck mounting.

One good one is to bandsaw a block of wood- shaped so that bottom slides on the lathe bed, the top is cut to the shape of the chuck when it is aspindle height.
you plop the chuck on and slide it up to the spindle nose.

Evans stick is a good idea.