You can discount the information based on prejudice if you want, but what
you have here is one of the reasons why I use dovetails, not compression
holds. If you squeeze a piece of wood, it'll seek accommodation by
compressing or working against the incompressible steel. Can be so gross as
to be visible, or so subtle as to pass without notice. Try bringing up the
tailstock with the piece only supported in the chuck, then tightening the
chuck. May not be absolute, but it will restore the status quo ante.

Your problem might be exacerbated by serrations on the inside of the chuck
jaws. They're generally symmetrical, and so as likely to push away as draw
toward the established shoulder when you tighten. They also break fibers,
making a precise remount less likely. The dovetail wedges itself against
the bottom, doesn't chew fibers, and if you use it properly - snug, not
cranked to the point of depressing the wood - automatically recenters if you
dismount.

Did you put your spur center point matched up against your tailstock point?

"Paul Kierstead" wrote in message
news
In article , "George" george@least
wrote:

Does the point meet the one you made at the tailstock when you chuck up?
If
not, you've got misalignment. Could be chuck, could be what it's
mounted
to. A point in the headstock should meet a point in the tailstock.

That is what happens. Actually, never mind the drill thing; it distracts
from the problem. If I do this:
1) Rough a cylinder between centers using spur and live center
2) Cut a tenon (parting tool)
3) Remount cylinder using chuck (Talon)
4) move tailstock back to cylinder.

in (4) the tailstock live center will not line up with the old point.
Now the tail stock has some play (it is not an exact fit between the
ways), but even the play is not enough to make line up. In my mind, this
would indicate the head is not parallel to the ways; how would one go
about fixing this? Of course the chuck could be bad too, but it is much
much better built then the lathe.

PK