Replacement 3 Jaw Chuck

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grandpaswagon

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I have a Craftsman (Atlas) 12"x36" bench lathe that has a broken 3 jaw chuck. I don't see where I can find the replacement parts to repair it, other than going through eBay (or similar) and getting something that may or may not work.

My question is, are all of the smaller chucks (say 6" and less) using the same spindle size and thread pitch? I looked in my manual, but it doesn't mention anything about the size of the threads that mount the chuck to the spindle. I did a quick measurement and they appear to be 1 1/2 x 8 tpi - does that sound correct?

There are a lot of chucks on eBay right now, and if I can just replace the entire chuck that may be the quickest way to get back to work.
 
Mark,

Yes, the Atlas (and Atlas/Craftsman) 9", 10" and 12" all have the same 1-1/2"-8 spindle nose threads.

Finding parts to fix a broken vintage chuck (or finding the correct and often missing alternate 3-jaw jaw set) is a very iffy proposition. So buying a replacement chuck is the quickest and safest course. Just do not buy any solid jaw (i.e., not 2-piece jaw) 3-jaw chuck unless either the photos show it with both sets of jaws or you write the seller and he confirms that it will come with all 6 jaws.

Robert D.
 
I have a 5" Union U-435, 3 jaw chuck, with a broken inside jaw. It is not a complete loss as I have the set of outside jaws for the chuck.
However, finding a set of replacement inside jaws for this chuck is looking to be harder than finding and honest politician.

So, I have been looking on eBay and there are ton of chuck options. My question is how big of a chuck can I reliably use on my lathe? 5 inch for sure, as that is what I currently have. What about a 6" or 8" chuck? I don't want to go any smaller than the 5" I currently have.
 
Mark,

It depends a little on what you usually work on. There was a lengthy thread on this subject a few weeks ago. But I can't recall the subject line. You might look for it. Pretty sure it was since Thanksgiving.

But for the most part, the standard chucks for a 12" seem to be a 6" 3-Jaw and an 8" 4-jaw. Based on the facts that 3-jaw chucks are generally heavier than 4-jaw and the swing over cross slide is usually in the 7" range and economics and probably other factors. So unless you have specific and repeated reasons for needing a larger 3-jaw, I would buy a good 6". Preferably one with 2-piece jaws.

Robert D.
 
Thank you much for the insight.

I was thinking of getting a replacement 6" and keeping my Union 5" in hopes that one day I will find a replacement jaw for the broken one.
 
Makes sense.

Robert D.
 
I gave up finding inside jaws for the OE chuck on my Logan. But I did find an identical chuck with inside jaws only for what I was willing to pay for jaws. So rather than fiddling with swapping jaws I just spin off one chuck spin on the other. Much easier
 
That makes sense, too.

Robert D.
 
grandpaswagon said:
I have a 5" Union U-435, 3 jaw chuck, with a broken inside jaw. It is not a complete loss as I have the set of outside jaws for the chuck.
However, finding a set of replacement inside jaws for this chuck is looking to be harder than finding and honest politician.

So, I have been looking on eBay and there are ton of chuck options. My question is how big of a chuck can I reliably use on my lathe? 5 inch for sure, as that is what I currently have. What about a 6" or 8" chuck? I don't want to go any smaller than the 5" I currently have.
Click to expand...

Mark,

I'm in the same boat as you. I have a 5" Union U-435, 3 jaw chuck, with a missing inside jaw # 3.

Rich
 
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