Lathe chuck jaw repair

A

abunai

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I have an old three jaw chuck that the jaws are not parallel to each other.
They do not hold even from the bottom of the jaw to the top.
Is there a way to fix this?????
 
I had an old 4 jaw LW chuck that was so worn it was either try to true the jaws or send it to the scrap yard. Rather than just toss it I decided to reprofile them on the surface grinder. I set them all in a line in the vise and trued them to the same length. Then repositioned them and one at a time recut the 45* angle at the tip. The final step was to recut the serrations on the tips.

The whole process took about 3 hours on a Kent automatic feed grinder.

As for a 3 jaw scroll chuck I think the best way to true the jaws would be to install a spider and grind them insitu. There is a Tubalcain video on the subject. "Machine Shop Tips #147 Grinding the Jaws on a 3 Jaw chuck"

 
If you use your chuck(s) daily like I do. Then I would not waste my time. I would buy a new chuck with the set-true feature. If the jaws are not like they should be. They will never be correct again. You cannot “correctly” fix a “worn chuck”. Grinding the jaws is not a fix. Some will argue with me and arguing is welcome…Dave
 
I’ve been trying to find jaws for this chuck (someone buffed them to death) with no luck , seems like a well made chuck
Ied like to get it serviceable again. I may try to make some top soft jaws for it
7C38F1B5-738E-496B-993F-5CB9D2C937B6.jpeg
It’s a Japanese ITI so-6x trademarked soul , came on a Sheldon 13” lathe , it fits my SB 10L also.
 
dlane
Those are top jaws, you should be able to find replacements for them. Or, push comes to shove, make some soft jaws and turn them to whatever you need.
 
I agree with T Bredehoft. It's hard to tell, but from the picture I believe you have the "American Standard" style jaws. They could be the serrated style, but in any case there are several companies that make replacements. I've ordered several sets of American Standard style soft Jaw tops for different size chucks over the years. Soft jaws come in either steel or aluminum, and usually cost between $35.00 and $75.00 depending on the size of the 3 jaw chuck. Some specialty soft jaws can be more expensive.

Hardened top jaws on the other hand can be expensive. Here's a link to a company that makes both hard and soft jaws:
http://tool.wttool.com/tools/lathe-chuck-jaws

This company makes soft jaws:
http://monsterjaws.com/
I have done business with this company, and they do make quality products at reasonable prices.

There are a number of other manufacturers. Just Google "replacement American standard chuck jaws" without the quotation marks
 
abunai, if a fix like Tubalcain shows in the video above is suitable to you, I would add a suggestion for controling grinding debris in addition to all the precautions he mentioned. Since a spinning chuck acts like a fan and blows grit and chips outward, adding some fibreglass tape around the steps on the jaws as shown in this picture will catch and hold an amazing amount of the bad stuff.

IMG_1108.JPG
 
There's some videos on YouTube on truing or grinding chuck jaws with a dremel held in adapter on the tool post maybe check those out and see if it's an option
 
There's some videos on YouTube on truing or grinding chuck jaws with a dremel held in adapter on the tool post maybe check those out and see if it's an option
Done correctly, that can make the jaws accurate at the exact diameter you have it set up at when you grind the jaws. If there is any wear or other inaccuracies in the scroll, which is pretty much a given, then the runout will still be off at any other diameters by that amount. It might still be worth doing if there is taper or other damage in the gripping surfaces of the jaws, even on a 4 jaw chuck.
 
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