Pm1127vf-lb New Chuck Or Back Plate

I've been guilty of not making sure a round piece is chucked properly when working toofast and using the center of the three jaws....got some pretty decent wobble out of it:eek 2:
 
As a practice, I learned early on that I need to wiggle the stock around to make sure it seats true to the jaws, so that is a non issue. I took the chuck apart, removed the back plate, removed all of the internals, cleaned, and lubed it all. I checked the run out of the spindle face and the OD of the hub register and all is well there. I did take a light facing cut on the spindle when I first got the lathe and all was still well there. I then bolted up the back plate and noted that the ID of the back plate had approx. .0025" of runout, even when mounted on the spindle. However, the outer register of the back plate was approx .001" runout. I decided to trim it back and cut a new register. I did that and got he chuck to mount well. Now when I chuck something up, I get a consistent .004" runout assuming I tighten it with one particular key hole. With the two other key holes, I get betweeon .005-.006" runout. For my work, when I need a 3-jaw, .004" will be just fine.
 
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