10-18-2020, 08:51 AM
Install your 3 jaw chuck on the lathe and chuck up a piece of 50mm or so stock and take a clean up cut to make sure it is running true. Mount the 4 jaw on the cleaned up portion of the material with the back of the chuck facing away from the headstock. Indicate the outside of the 4 jaw so it is running true then use your DTI to inspect the back of the chuck. If it is not running true then take clean up cuts to true it up. You have not said what type of spindle nose you have but if it is a camlock (D type) make sure you inspect and true up as necessary the angled portion. Make sure you cut the angle (taper) correctly and also face off the back of the chuck to make sure it seats properly.