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Grinder Attachment for Trueing up the 3 Jaw chuck

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vtsteam:
I'm afraid this one hardly merits "Project" status.

I have an old Atlas/craftsman 12" x 36" lathe which I've used very little. It has been in storage mainly, and I finally cleared out enough space around it to do some machining. I tend to use the faceplate a lot, and turning stuff between centers. It does have a 3 jaw chuck, and I haven't paid much attention to it. But today when drilling out some pulleys I with the 3-jaw had a difficult time adjusting them to center. The old paper under one jaw trick couldn't take up the excessive amount of runout.

So I decided to stop and do something about it. I had a Dremel in a drawer and conveniently one new stone for it right by. On a shelf near the lathe I saw an unopened tube of JB Weld epoxy putty. I also had a piece of 5/16" key stock in my scrap box, so I sawed off a chunk, grabbed the other items and trudged back to the house. Shop temperature is 30F today so no gluing there!

Back home I rough sanded down a spot on the Dremel. Then I cut off a chunk of the epoxy putty and warmed it up for 10 seconds in the microwave and kneaded it. Stuck the keystock onto the Dremel with the putty and smoothed it down with a wet finger. JBWeld epoxy putty cures quickly -- you have about 3 minutes to work it, and full cure is effected in only an hour. I've found to be a very high quality and tough material, and to give a good bond. Other brands I've tried never worked as well, or cured as quickly.

It was rock hard in a half hour, so back down to the shop, and popped it into the tool holder. A few adjustments later and with the lathe turning at its highest speed to keep the jaws out at edge on the scroll and the grinder running, I just touched the stone to the jaws enough to see a couple sparks. Traversed in to clean up the jaws. switched off, and back out. Then repeated a couple more times until I could just see a few tiny high spots ground off on the jaw that was the narrowest -- the others had been ground a little bit more. And then called it done. Worked fine, and the pulleys were easily centered and drilled.

Anyway here are the ingredients:

vtsteam:
Glued up:

vtsteam:
And ready to position for grinding:

philf:
Hi vtsteam,

There was some discussion about truing 3-jaws some time ago.

http://madmodder.net/index.php/topic,4145.0.html

It's important to load the jaws as though they're clamping something whilst you grind them.

I posted a photo of my solution but something has gone amiss with the image so here's another version:



Basically the angle of the jaws clamps on the sides of the slots in the tube and the point of the jaw protrudes through the slots enabling them to be ground.

Cheers.

Phil.

vtsteam:
Hi Phil, thanks! Looks like a good solution to doing a good job of it. Thanks for the thread reference -- I read it through. I had heard that spinning the jaws at the highest lathe speed would do basically the same thing by centrifugal force acting on the jaws to keep them tight to the scroll. That seems to have worked for me.

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