Union chuck issues

S

sandmanred

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I have this crack in my chuck and I'm wondering what to do. It's a Union 4 jaw 6 inch 6628. I'm guessing it was dropped some time ago. It functions okay as far as I can tell. I was able to chuck and center a 1.5 inch round bar within 0.001 all along about a a 4 inch length of cantilevered bar. And the faces of the jaws are within 0.002 when engaged with a work piece.

The options I see;

  • Leave it alone.
  • Weld it up with no filler
  • Gouge it out with a carbide burr and weld it up

Any other suggestions or comments on either option or any other options to consider? If welding is a recommended can anyone tell what material this might be and the recommended filler rod and process?





 
Do a Dye Pen check to see how big the crack really is, and run to failure.
 
For the money you save keeping it might not be worth the injury caused.
 
Most of those older chucks were made of cast iron and have been soaking up oils for years making them almost impossible to weld effectively. Besides that that chuck should never be turned to any more than 60 to 70 rpm and even at that it may not be safe ! I would put it in the scrap bin !
 
Bronze welding would be the safest but I agree with frankly2 get a new chuck for the lathe and turn that one into a holder for a mill. There is a lot of stress when spinning which is why chucks have speed limits.
 
I would say your pressing your luck if you mount that chuck on a lathe. I would bring it to a engine repair shop and have them magna flux it. That will show the extent of the fracture. Would be a good rotary table chuck or welding positioner?
 
I agree with the others, trash bin or a work holder for a rotary table.
 
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