Atlas brand 4-jaw

[cdhknives]

I took apart my very dirty and neglected 4-jaw that came with my grandfather's lathe. IT came apart and went back together pretty easily, and a toothbrush + WD-40 took care of the gunk. Two questions:

1) The set screws on the back that hold in the U shaped retainer for the adjustment screws were loose. When I tighten them, the jaw adjustment screws are very stiff. Should they be snug (in which case I have a problem) or left loose?

2) One of the jaws has a different, much finer and smaller in diameter, adjustment screw. It is also a duplicate #4 (missing #2) so I assume at some point one jaw got lost or damaged. The smaller adjustment screw rattles around a bit, but once torqued down seems tight enough. Problem or not?

 

[pdentrem]

I never had the 4 jaw completely apart so I can not speak about the retainers but if the one oddball adjustment screw holds then it is no issue. Unless you have to use alot of force then it may skip teeth if it is too loose.
Pierre

 

[wa5cab]

I don't know about the set screws, either. I would tighten them for best fit, run the chuck for a while, and see whether they tend not to stay adjusted. If they tend to get looser, I would apply a drop of blue Locktite and let it cure before operating the chuck. Or buy four nylon insert set screws.

On the odd jaw and lead screw, my guess is that some PO lost the #2 jaw and replaced it with the #4 from a different make chuck. The replacement jaw may have required a different pitch and/or diameter lead screw and it isn't a good fit in the Atlas body.

Robert D.