Hi Icrum
Tool rest 1/8" out over 6", that's certainly not a lot, however if it
was right on, it would be better.
First question what is off, toolrest or banjo, to find out, set banjo
at 90 degrees to the lathe axle and measure from lathe bed to top of
toolrest, swing toolrest 180 degrees and measure again, no change ??
than it is not the rest, and it could be the banjo, also how much play
in the banjo opening for the toolrest, how is the tool rest post, nice
and smooth or burred up by the fastener, and what's the toolrest made
of, a what I would consider long rest can easily drop by 1/8" on that
length if there is some wear, or a combination of wear on the banjo
opening and the tool rest post and the banjo bottom.
I assume that the rest is still a cast iron one, if wear is the case
you could braze up the toolrest post and make it fit better again, if
it is a steel toolrest, it would not take much to change the height
difference, and if the banjo has worn on one side, that could be
rectified by either brazing on some new material or by filing the banjo
so it is even again.
Also it is very easy to make an other rest, a piece of cold rolled
steel and some angle iron, weld it, and you have one, or some other
combination of metal, and make some shorter rests while you're at it.
If you want to use a long rests I would advise to get 2 banjos and a
rest with 2 posts, makes for a much better rest, (less vibration, less
adjusting the banjo etc)
I don't know what your plans are in turning, but I think the problem of
your banjo being off is not a big deal, imagine a 12" spindle you turn
that is 1/4" smaller on one end than the other, would that prevent you
from working with your lathe ??? of course not.
If you where to go and make a lot of dough rollers it would be a pain,
but as soon as you make any curves or cut into the spindle to make
coves or beads, a concave or convex surface, it would not make any
difference to you that the tool rest is of by 1/4" over that 12" length
I have a pic. of a tool rest I made and also of one that Leo Lightman
made and some other stuff, you can have a look if you like.
http://homepage.mac.com/l.vanderloo/PhotoAlbum25.html
Have fun and take care
Leo Van Der Loo