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Craftsman 4 Jaw Chuck Screw

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cbrims

Steel
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#1
I was working on cleaning up everything I've got for my lathe and when I started on the 4 jaw chuck I noticed a chunk of one of the screws had been broken where the T handle connects to the screw. I've searched all over the place looking for replacements; new old stock at SearsPartsDirect.com, a used chuck on eBay and Lost Creek Machine, and searches on Google; I've come up empty handed. I've got the 101.21581 chuck and pickins are slim. Are other screws compatible? Am I better off looking for a different chuck? Or is there an option I've overlooked?
 

wa5cab

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#2
You didn't say whether your 4-jaw is the 6" (Atlas 6644) or the 8" (Atlas 6646). But 101.21581 crosses to 9 GT 21581 which crosses to Atlas 6646 (8"). The only documentation on the chucks that we have are various Atlas and Sears catalogs and an Atlas 2-page instruction sheet and replaceable parts list. So the part that you are looking for is Atlas # 6646-51. What I would do is to call Clausing and ask whether or not they still have any of those. Probably not, but they've surprised me before. If they don't have it, ask whether or not they still have the drawing for it. If they do, ask them to send you a copy, and forward it to me. If you cannot find someone selling a damaged 8" 4-jaw cheap, you can make a screw. Of course, the difficult part will be the square socket in the outer end. For that you probably have two choices. Find a near-by machine shop that has a rotary broach of the proper size. Or drill the end for the starting hole and single-tooth broach it on the lathe, using the indexing pin for positioning the spindle.
 

cbrims

Steel
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#3
I don't have the chuck with me, but I do believe it is an 8" chuck. I will start by calling Clausing and if they have a drawing, I will get it to you. Then I'll start checking out the different options available if I can't get anything from Clausing. Thank you for the information.
 

cbrims

Steel
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#4
Well, I called up Clausing, told them the part number, they transferred me to Pratt Burnerd, they didn't have the part. I asked about the drawings, they said they don't have it. So I guess I'm going to keep checking all the sites. I'm in the process of rebuilding the lathe, then I'll be onto learning how to use it. I'm not in need of the 4 jaw chuck right now. Once I learn how to thread and everything, I'll work on making a new screw.
 

David S

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#5
Once you get down to trying to make a replacement, don't discard making a two piece solution. Figure out how to cut the thread.

Then make a separate piece with a square hole and silver braze it to the threaded piece.

David
 

Randall Marx

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#7
It might even be possible to use something that already has the square hole in it as part of the two-piece solution. I'm thinking of something like a socket or extension from 1/4" or 3/8" drive socket wrenches.
 

wa5cab

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#8
Well, I called up Clausing, told them the part number, they transferred me to Pratt Burnerd, they didn't have the part. I asked about the drawings, they said they don't have it. .
OK. I was pretty sure that Atlas never made chucks (or motors). But thought that they might have had the parts drawings.
 

bobl

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#9
I was working on cleaning up everything I've got for my lathe and when I started on the 4 jaw chuck I noticed a chunk of one of the screws had been broken where the T handle connects to the screw. I've searched all over the place looking for replacements; new old stock at SearsPartsDirect.com, a used chuck on eBay and Lost Creek Machine, and searches on Google; I've come up empty handed. I've got the 101.21581 chuck and pickins are slim. Are other screws compatible? Am I better off looking for a different chuck? Or is there an option I've overlooked?
I have some that came with my heavy 10 don't know if I have one that you can use give me a picture and dimensions and lets see if I can help you


Sent from my iPod touch using Tapatalk
 

cbrims

Steel
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#10
I have an update in the information. I was going through a box of tooling and bolts that came off the lathe and I found the piece that broke off of the adjustment screw. Would this in any way be repairable or is it more work than it's worth and I should consider making a new screw?
 

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wa5cab

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#11
You could try brazing or welding it back on. It doesn't appear that you have anything to lose, other that a little time.
 

whitmore

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#12
Once you get down to trying to make a replacement, don't discard making a two piece solution. Figure out how to cut the thread.

Then make a separate piece with a square hole and silver braze it to the threaded piece.
This outfit can supply the hole...
<http://www.sturdybroaching.com/contact-us-2>
if the threading isn't a problem. Until then, a four jaw chuck with three working
jaws isn't a lot of fun.

Making four screws, and switching out the square-drive key for a hex tip,
you could just braze Allen screws (big 'uns) into tapped holes. Or use threadlock.

I can't imagine how the original could break, and still be un-stretched enough to
take a braze-together fix.
 

cathead

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#13
A repair using silver solder might be a viable option for you. I fixed a chuck jaw that way and it works fine.
Silver solder is great for these kinds of repairs because of its high tensile strength. I wouldn't even consider
using brass(braze) for a repair like that knowing that silver solder has two to three times the tensile strength.
 

cbrims

Steel
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#14
I have to see how the broken piece fits into the screw, if it feels like it seats nicely, I'll look into what it's going to take for silver soldering. Otherwise I'll go back to my original option of making a new one. I still need to build a tool to remove the plug that holds the screw in from the back.
 
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