Slingshot, I recently went thorough the same issues with a new 4jaw. I did the following tests :
1. Remove all the jaws and run a DI on the face of the chuck to confirm that the chuck is running in axial alignment with the headstock, also do this on the side of the chuck to verify radial alignment. Do the above for each bolt position on the chuck (normally 4) and note which gives you the best results. Give axial alignment priority as you can dial out radial with the jaws when working.
2. Once you have the chuck body aligned move onto the jaws. Replace them and Mount a test bar, dial it in near the headstock the run your dial indicator out to about 6" and check runout note how much runout and in what position the high point is relative to the jaws. Now remove the jaw where the high point was ands swop it with the jaw opposite it. Again chuck up your test bar and perform the same test. If the high point moved with the jaws you can be certain that the error is with your jaws and not the headstock. For me this was the case. You can resolve this by grinding your jaws. However what I did first was to make up a list of every permutation of jaw to slot (24 combinations, hint label the jaws and slots) and perform the above test with each combination noting the resulting runout at 6". I found a best case of 0.06mm at 100mm (I work in metric) which I ended up using and did not need to grind my jaws.
1. Remove all the jaws and run a DI on the face of the chuck to confirm that the chuck is running in axial alignment with the headstock, also do this on the side of the chuck to verify radial alignment. Do the above for each bolt position on the chuck (normally 4) and note which gives you the best results. Give axial alignment priority as you can dial out radial with the jaws when working.
2. Once you have the chuck body aligned move onto the jaws. Replace them and Mount a test bar, dial it in near the headstock the run your dial indicator out to about 6" and check runout note how much runout and in what position the high point is relative to the jaws. Now remove the jaw where the high point was ands swop it with the jaw opposite it. Again chuck up your test bar and perform the same test. If the high point moved with the jaws you can be certain that the error is with your jaws and not the headstock. For me this was the case. You can resolve this by grinding your jaws. However what I did first was to make up a list of every permutation of jaw to slot (24 combinations, hint label the jaws and slots) and perform the above test with each combination noting the resulting runout at 6". I found a best case of 0.06mm at 100mm (I work in metric) which I ended up using and did not need to grind my jaws.
