On 2008-07-15, Bruce in Bangkok wrote:
On Mon, 14 Jul 2008 11:41:55 -0400, "Joe AutoDrill"
wrote:
[ ... ]
Is it something you can take off, measure up and have someone make for you
for less? If they did this, would you be guaranteed to have less slop?
I read posts like this frequently but in reality any machine tool
built before the advent of ball screws had backlash in all its
adjustments. Apprentices were taught to cope with this problem by
making all adjustments in the same direction - opposite to the force
being applied by the cutting tool. In your lathe's case, assuming
normal turning operations, you back the tool off and then readjust it
toward the work until you reach the dial setting you had used for the
previous cut and then as much more as you want for the next cut.
And -- one thing which you can do is to mount a dial indicator
with a two or three inch travel so it measures the motion of the cross
slide. This will be more accurate than a worn leadscrew in a worn nut.
(If it were just the nut worn, you would have the same backlash all the
way through the range, and your dials would be accurate enough.
However, if the leadscrew is worn, that will be more so in the middle of
the range, and will introduce extra errors -- unless you are measuring
cross-slide travel with something which does not depend on the
leadscrew.
My 5418 had the leadscrew and nut so badly worn that it was
producing 0.070" of backlash in the middle of travel -- and this on a
1/2" diameter leadscrew which produced a full 0.100" travel per rotation
when in good shape.
However -- the leadscrew and nut were a lot less expensive for
mine -- at least back when I got it. :-)
If you want less slop then just make a new nut.... after all, you've
got the lathe to bore and thread the new nut.
And at least you have a larger bore than I did. Beware that you
will probably need to make a left-hand thread ACME, not just a normal
ACME if your cross-slide is like mine. Check it out before you order
anything.
Good Luck,
DoN.
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