lathe aligement problem

[Tozguy]

I'm guessing you are using a self centering chuck that is not centering perfectly. If so that is normal since they are not perfect, however some are much better than others. I you want it to line up you will have to use a four jaw chuck and dial gauge. Have fun!

I agree. Chances are the repeatability (or lack of it) of your scroll chuck is what you are seeing. A simple test would be to turn one end, remove it from the chuck then put it back in the chuck the same way without flipping it. Take another cut and see how concentric it is.
Standard procedure using a 3 jaw scroll chuck is to do all the cutting before removing the work. Once you remove the work don't count on the work being held the same a second time.

 

[mack318]

I would check everything in your set up. cross slide, compound slide, tool post, cutting tool.

I have a QCTP and one time the tool was slipping in the tool holder, producing a irregular cut to say the least.

stupid stuff will mess you up. Hey are those metal chips on the jaws of your chuck? you wont get a good clamp on your work piece like that, even if you use a 4 jaw chuck, once you start cutting, it will stop running true, maybe even walk itself out of the chuck creating a dangerous situation.

what cutting tool are you using? from your description it sounds like a facing cut, turning cut or both. are you using the right cutting tool for the type of cut your making? is it correctly sharpened?

forcing a dull cutting tool into your work piece can cause some HUGE irregularity's in your cuts.

anyways i hope that helps

_mack318