NickG's thread regarding chuck runout in the "How Do I" forum plus a comment by my son prompted me to do some research on the chuck that came with my X2 mill.
I set up my DTI and started measuring. Starting at the spindle I found the runout to be less than .0005"
How Precise is Your Chuck?Moving to the top of the chuck sleeve I found that each time the chuck was tightened a different reading might be found. The largest error I found was .0105" and once it was as little as .0045"
How Precise is Your Chuck?Moving to the middle of the sleeve the reading improved to .008". It once measured .006"
How Precise is Your Chuck?Moving to the bottom of the sleeve, just above the teeth for the key. I got a reading of .007". For some reason this reading was fairly consistent each time I measured at that point.
How Precise is Your Chuck?Measuring the chuck body, just at the chamfer, the reading went back to .0005", about the same as the spindle measured.
How Precise is Your Chuck?To represent the tool runout I chose a center drill as it was ground and polished. Here I found that each time the tool was inserted it would measure slightly different. The best reading I got was .00125" but I also got as high as .0025".
This was done by removing and replacing the same tool. While I did not try it I would suspect that a different diameter tool would give a different set of readings.
How Precise is Your Chuck?As the sleeve runout has no bearing on accuracy it really does not matter. The interesting part is that while the chuck body was very concentric the variation in the jaws spoiled it.
Joe
