I have recently purchased a SIP 36" lathe. It has a single bar bed
with key underneath to align the head and tailstocks. The tailstock
keyway has quite a bit of play in it and this play is taken up by a
pin, grubscrew and locknut. To align the tailstock I position it so
that the tailstock centre and drive centre are in line and then adjust
the pin/grubscrew. Problem is that the pin/grubscrew needs to be so
tight that the tailstock will not slide on the bed and if it is any
slacker then there is sideways movement in the tailstock and
misalignment.
Has anyone experienced this problem and how did you overcome it ?

"LesC" wrote: (clip) Has anyone experienced this problem and how did you
overcome it ?
^^^^^^^^^^^^^^^
My Harbor Freight knockoff of the Sears monotube lathe had that same
problem. I got rid of the problem by buying a better lathe. I also had
trouble with the monotube rotating slightly, causing the tailstock to move
off axis. It is held by a single setscrew (grubscrew), which is not secure
enough.

In article ,
(LesC) wrote:

there is sideways movement in the tailstock and
misalignment.

I've used a lathe that's similar to this. Basically, you accept the
tailstock being somewhat out of whack. Since you are not cutting with a
fixed tool as in a metal lathe, a slight offset of the tailstock does
_not_ automatically imply cutting a taper. Precision alignment is not
really needed for spindle turning - it's nice, and buyng a better lathe
is the way you get it, but it's hardly needed - consider all the crudely
knocked-together wooden lathes of yore...

I have an old lathe which had a half-assed rebearing done that I have
not corrected yet. It has a vertical misalignment of the tailstock
center. Other than holes drilled from the tailstock being somewhat
larger than the drill bit, it has not practical effect on turning - the
only place it would be much of an issue would be on really short work
mounted on a faceplate or chuck, which I can do with no tailstock. If
you feel that you must use a tailcenter on faceplate work, it does have
more of a need to line up "perfectly".

--
Cats, Coffee, Chocolate...vices to live by

That gives me a warmer feeling about the tailstock of my wood lathe wobbling
a few thousand of an inch or more. Come to think of it if the weldment
construction or casting housing the bearings are not normalized after
fabrication it will move and get the bearings out of line after a while.
When making precision lathes to machine metal the entire lathe is
normalized. Then the bearing housing is machined, honed and in line bearings
are installed.
The bed is then machined or better still hand scrapped to a set tolerance to
maintain the perpendicularly and parallelism with the tailstock.
I have doubt that when making lathe to turn wood the same procedures are
used. For sure this tolerance is none existent with low end wood lathe. As
for high priced lathe I welcome comments as to what standard the
normalizing is done and to what tolerance the final machining is done.



"Ecnerwal" wrote in message
...
In article ,
(LesC) wrote:

there is sideways movement in the tailstock and
misalignment.

I've used a lathe that's similar to this. Basically, you accept the
tailstock being somewhat out of whack. Since you are not cutting with a
fixed tool as in a metal lathe, a slight offset of the tailstock does
_not_ automatically imply cutting a taper. Precision alignment is not
really needed for spindle turning - it's nice, and buyng a better lathe
is the way you get it, but it's hardly needed - consider all the crudely
knocked-together wooden lathes of yore...

I have an old lathe which had a half-assed rebearing done that I have
not corrected yet. It has a vertical misalignment of the tailstock
center. Other than holes drilled from the tailstock being somewhat
larger than the drill bit, it has not practical effect on turning - the
only place it would be much of an issue would be on really short work
mounted on a faceplate or chuck, which I can do with no tailstock. If
you feel that you must use a tailcenter on faceplate work, it does have
more of a need to line up "perfectly".

--
Cats, Coffee, Chocolate...vices to live by