07-01-2013, 08:41 AM
.750 sticking out 10".. Well, .0005 is a great figure but you tested the chuck against an unknown and possibly got a meaningless result. A proper test means making chips.
You should make some chips from a 1" diameter bar (half of maximum length) mounted between centers (don't use the chuck). Then do a long one (full length) between centers and compare results. That will test bed and tailstock alignment.
You should try the short one with the tailstock quill both extended and retracted (re-locate the tailstock), running an indicator along the top and sides of the work. This will test quill alignment.
Finally, turn a bar about 4 inches long mounted in the chuck alone (don't use the tailstock). That will test headstock alignment. See if the work is actually round. That will test the spindle bearings.
You can use a few collars glued to the bars to save material and time, and as a bonus taking tool wear out of the picture. Not important, but the bars would best be hollow with a thick wall, and RPM should be kept low to minimize things from winging about from being out of balance. Nitpicking a bit..
Btw, the Rollie test doesn't take sag into consideration but it takes a lot of sag to influence the result. You don't need a level to "level" a lathe, the Rollie test works fine. A level is faster/easier.
You should make some chips from a 1" diameter bar (half of maximum length) mounted between centers (don't use the chuck). Then do a long one (full length) between centers and compare results. That will test bed and tailstock alignment.
You should try the short one with the tailstock quill both extended and retracted (re-locate the tailstock), running an indicator along the top and sides of the work. This will test quill alignment.
Finally, turn a bar about 4 inches long mounted in the chuck alone (don't use the tailstock). That will test headstock alignment. See if the work is actually round. That will test the spindle bearings.
You can use a few collars glued to the bars to save material and time, and as a bonus taking tool wear out of the picture. Not important, but the bars would best be hollow with a thick wall, and RPM should be kept low to minimize things from winging about from being out of balance. Nitpicking a bit..
Btw, the Rollie test doesn't take sag into consideration but it takes a lot of sag to influence the result. You don't need a level to "level" a lathe, the Rollie test works fine. A level is faster/easier.