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cdhknives

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#1
I am tired of my wobbly chuck and might have some budget to change it. I really don't think a high $$$ chuck is appropriate for our light duty Atlas lathes but I would like something better than my oft crashed Union 6" 3 jaw. My look has focused on the Shars options. If it truly holds 3 thou or less runout it is a good improvement over mine.

http://www.shars.com/products/workholding/lathe-chucks?mounting=1-1/2+-+8

Are these a reasonable compromise between cost and quality for a 10" Atlas? I would prefer a single body, not a plain back, due to weight and length, but these are priced right and the back plate is included.
 

wa5cab

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#2
Although I have no personal experience with Shars, they do have a pretty good reputation. I would personally go for the one with the 2-piece jaws, as I have one by Pratt-Burnerd that is similar (but today about triple the cost). Especially as the Shars one is on sale for a little less that the one with solid jaws.
 

4ssss

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#3
If your Union is "oft crashed" the Shars will be "oft crashed" as well.
 

cdhknives

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#4
:rolleyes: Tongue in cheek. I hit it once several years ago (with the tool in the lantern post) under power which stalled it (from low speed, maybe 250 RPM, and it bent over the carbide insert tool only), and I spent an hour or two getting the one jaw to run smoothly again. When I got it the chuck was 50 years old and FAR from pristine which tells me all I need to know...that and the major runout. Since then I have replaced galled and pitted bearings and cleaned up lots of nicks and such in the bed, so maybe it will run more true with a better chuck.
 

markba633csi

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#5
I have a Shars 4" on my 6 inch Atlas. It's ok, around 3 thou runout. I did have a problem with 1 of the jaw sets- after some back and forth they sent a new set which is acceptable. If you buy one, be sure to check it thoroughly when you get it, with both sets of jaws. Also one of the pinion retaining screws was drilled a bit off but it's a minor thing. The backplate took some time to machine; the hub needed about 1/2" of material removed. This is Chinese stuff so you have to expect things like that. It's a cost-effective option.
Mark
 

chippermat

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#6
Although I have no personal experience with Shars, they do have a pretty good reputation. I would personally go for the one with the 2-piece jaws, as I have one by Pratt-Burnerd that is similar (but today about triple the cost). Especially as the Shars one is on sale for a little less that the one with solid jaws.
I feel like I should already know this, but why the preference for 2-piece jaws over reversible jaws?
 

pontiac428

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#8
If Shars quotes .003", then it's at least that good. I don't have a Shars lathe chuck, but I have bought a couple of drill chucks from them and been very pleased. I like Shars quality quite a bit, and the price is right. They spec a lot more QC into their catalog items than other China importers.

If your chuck isn't hammered to death, you could grind the jaws with a tool post grinder to eke a couple thou of center accuracy back into it. Probably lots of different points of view on how that is best done, but it is an option to try before you drop your hunk into the bin.
 

4ssss

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#9
I feel like I should already know this, but why the preference for 2-piece jaws over reversible jaws?
It's for those that "oft crash" into their chuck. You can just replace the top jaws instead of the entire thing, and you can also make them for a specific job.
 

chippermat

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#10
Interesting points regarding 2-piece jaws, gentlemen, thanks for the insight.
 

kd4gij

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#11
2 piece chuck jaws as said are faster to switch. Plus you can get or make soft jaws and open up a hole new world in machining.
 

wa5cab

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#12
And one other point in favor of 2-piece jaws - every 3-jaw (and all of the relatively rare self centering 4-jaw) chucks comes new with two sets of jaws (called by various names but Inside and Outside are common choices). Unfortunately, if you buy a used 3-jaw, at least judging from the photos and descriptions on eBay, 90% of them the PO has lost the 2nd set. That isn't usually the case with 2-piece jaws. And if the removable jaws are missing, 98% of the time you can buy brand new ones from any decent machine tool supply house. Which you cannot do with one piece jaws.
 
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