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Replacement 3 Jaw Chuck

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grandpaswagon

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#1
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.
 

wa5cab

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#2
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.
 

grandpaswagon

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#4
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.
 

wa5cab

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#5
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.
 

grandpaswagon

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#6
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.
 

wa5cab

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#7
Makes sense.

Robert D.
 

AR1911

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#8
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
 

wa5cab

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#9
That makes sense, too.

Robert D.
 

MACH-4

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#10
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,

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
 

wa5cab

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#11
Generally, 3-jaw chucks are heavier than 4-jaw (because of the scroll, mostly). And chucks with 2-piece jaws will usually be heavier than ones with solid jaws. With either type, you have to make sure that you don't run the jaws out so far that they hit the ways or saddle wings, which can happen with an 8" chuck. A decent 8" 3-jaw is going to be expensive and weigh a ton. Stick with the best 5" or 6" you can afford. And maybe buy an 8" 4-jaw.
 

Wierd Harold

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#12
Like Robert said , a lot depends on the type of work you do. I have both a 3 and 4 jaw 6" and the headstock mount Jacobs chuck but what I use the most is beautiful little Craftsman 3" 4 jaw . I make both a lot of small parts and also long tubes that I turn off center to make variable thickness walls.
HWF
 

navycwo

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#13
I have the same Union U-435 chuck with a broken # 2 jaw. Maybe we can get one good chuck out of the three chucks or even two chucks depending on which jaw grandpaswagon needs?
 

wa5cab

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#14
That might well work.
 

navycwo

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#15
I have a good #1 & #3 jaw plus the whole chuck with a 1 1/2 x 8 TPI thread that I don't need since I bought another chuck.
 

G7564

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#16
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.
I have a complete chuck with both sets of Jaws message me if your interested. I know its about 3 years late but I thought I reply
 

wa5cab

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#17
No, they are not all the same. 1-1/2"-8 is common to a lot of 9" through 12" lathes. But 1"-8 is another common size. It is used on the Craftsman 101.07301 6" made by Atlas, and apparently a lot of smaller wood lathes that Sears used to sell. 1"-10 was the size that Atlas used on the 612, 618 and MK2 6" lathes and on the mills. 3/4"-16 was once another common size found on small chucks. However, whether or not you need to worry about what the threads are depends upon whether or not your existing threads and register area are bad. If they aren't bad, then you could possibly find your repair parts on another model number chuck. But it probably has to be from the same contractor.
 

G7564

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#18
No, they are not all the same. 1-1/2"-8 is common to a lot of 9" through 12" lathes. But 1"-8 is another common size. It is used on the Craftsman 101.07301 6" made by Atlas, and apparently a lot of smaller wood lathes that Sears used to sell. 1"-10 was the size that Atlas used on the 612, 618 and MK2 6" lathes and on the mills. 3/4"-16 was once another common size found on small chucks. However, whether or not you need to worry about what the threads are depends upon whether or not your existing threads and register area are bad. If they aren't bad, then you could possibly find your repair parts on another model number chuck. But it probably has to be from the same contractor.
The one I have is a 5" Union Chuck U-435 it has 1 1/2 -8 thread
 

G7564

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#19
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.
My chuck is a Union U-435 has both sets of jaws it is for sale
 
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