Grinding the small 4" 618/101. Chuck Jaws

benmychree said:
I wonder if your lathe's wear situation makes the finish grind tapered, that may account for the problem.
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I've been lathing 3/4" x 9" door pins and there was a .003" difference at the chuck and I had to use a file to make it match the tailstock end. All in all though the lathe is really running great. Even better than I figured I'd ever get it to perform.
 
I just watched a video on YouBoob about accurizing the small lathe chucks. Drilling and tapping four holes for set screws to align the backplate to the chuck body. This may be the answer to making my chuck more accurate. Check out the video and see what you think!

 
Worked on the chuck this morning trying to get my runout better than the .006" that I had read last night. Loosened the three backplate screws and then loosely snugged them. Used my dial indicator and tapped high spot and low spot and was able to get it at .001". Sequencely tightened the screws three times, until tight, and rechecked. "YES!" It held at .001" which is close enough for me.
 
Did a test cut tonight on a 3/4" cold rolled sticking out past the chuck about 3". I still have .001" runout "butt" there is .003" difference in the cut between the chuck and other end. I gave slight pressure upward on the chuck and got about .020" or more movement. I tried tightening the bushings but they get too warm. Seems like I put new bushings in it about a year ago when I did the restoration. (Can't really remember.) I have had the spindle out numerous times and may have damaged them in the process. Guess I gotta order some new bushings from Clausing unless someone knows where I can buy them otherwise.

(Is there anyway to knurl the inside of a bushing?)
 
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