Bummer! Got my chuck today and its stuck

[Dale_z28]

I bought a 6" chuck on ebay knowing it wasn't top o' the line, but I expected it to at least open and close fully. Not! It's built rather cheaply, which I can live with, but the innards are jammed-up in such a way that I can only open the jaws halfway before they stick.
It only has one hole for the key, works like the ring and pinion in car's rear end. On the opposite side of the "ring gear" (from the "teeth") is where the jaws mesh, and I don't see what's causing the binding but I also didn't buy it expecting to have to work on it, or have it not work!
Rant Over. I feel better now, sort of...

 

[darkzero]

What brand (well known or Asian import) & was it new or used?

 

[GA Gyro]

I suspect dis-assembly and inspection... will reveal the issue.

You have our curiosity up... :thinking:

 

[xalky]

Did you try oiling the scroll really good? Sometimes little chips get in there from the manufacturing process which can jam it up pretty good. Try blowing some air in there too. blow the chips out as you rotate the scroll around. This happens to existing chucks on a lathe too. It probably shouldn't happen to brand new chuck, but you do get what you pay for, it might be really minor hopefully.

 

[Dale_z28]

OK, here's the scoop. It was a used chuck, the seller knew nothing about it (bought it at an estate sale I think). It had no key and it has no markings other than the jaw positions 1 thru 3. Since it was an ebay purchase I didn't want to tear into it until settling the dispute (seeking to return it) about the item. I got an offer of a partial refund of $25 (I paid $35 plus $12 for postage). I accepted because I THINK I can get it back to working order. The back comes off to reveal the "ring gear" that is driven by what appears to be the end of a drill-chuck key that rides in a recess in the body of the chuck, sandwiched between the main body and back. It IS full of shavings. The jaws jam when adjusted outward at about their halfway point, and I agree, a good cleaning will probably cure it. I'll disassemble it completely this weekend while the wife hosts a cookie exchange. I'll post pictures and hopefully I'll discover something good about this purchase!

 

[xalky]

That'll probably cure it. Thus happens to high quality chucks too sometimes. So don't despair, you probably have a perfectly good chuck that just needed a little tlc.

 

[Dale_z28]

Tore it apart tonight


Chips weren't surprising, but a couple dings may have stopped the jaws



Also the "key" (internal, that is - for lack of better term) is cracked and has been brazed in an attempted repair



The jaws slide without too much drag with the scroll removed



A bit of stoning and I think it will be usable!
I wouldn't mind finding a replacement for this internal key, but if I'm easy on this one, it might do the job.
Thanks to all for the encouragement.

 

[12bolts]

Do you have a useable chuck without that 1 working? If that pinion gear isnt too hard and there is enough meat to play with, what about turning it down and putting a collar on it to reinforce it? Or cut a square hole in a new piece of steel and turn the broken piece off and weld the new one on.
On 2nd thoughts as you dont have a chuck key anyway, get a big SH cap screw to suit and weld it on then turn it to fit. Then you just need an allen key to operate your chuck

Cheers Phil

 

[Dale_z28]

Thanks! The socket-head capscrew is a great idea! The square socket in the existing (pinion gear IS what it amounts to) "key" is basically a 1/4" drive-sized opening and it appears it cracked upon some forceful tightening.
I'm heading out to work on it some more....

 

[hman]

Wild hair of an idea:

The pinion looks like it has a pretty narrow OD where the chuck key sockets in - weak enough that it cracked under stress. You might consider turning a ring to fit around the OD of the pinion, maybe 3/8" long, and with a nice, hefty OD. Braze it on, and it should strengthen the pinion in the stressed area. Then assemble just the front and back of the chuck and bore the hole to the appropriate OD and depth for the modified pinion.