off center turned blanks

[nonimac]

Hello,

I have only been turning pens for about a year now. Recently I have noticed that the last few blanks I turned have been off center. Meaning thin on one area and thick in another. I am wondering what could be the cause of this. I have a strait mandrel. If anyone could offer any insight I would appreciate it.

 

[D.Oliver]

Is it possible your are tighting the nut down too tight and causing the mandrel to flex?

 

[butchf18a]

If you are certain your mandrel is not bent; Derek is right about tightening the nut excessively. There is another possibility; when you set and then tighten your tailstock, it is easy to over-tighten and bend the mandrel. When you loosen the tailstock to remove the pen, the mandrel will return (material memory) back to straight.

 

[nonimac]

It is very possible. I have never thought about that, I am going to loosen it up and see if I can true it up. thanks for the replies.