Re: Backlash Fixes: South Bend Lathe


Webb Wyman <lynnw@...>
 

Hi There,

I have been following the threads on "Backlash" with great interest. The
latest posting by Chris prodded me into responding. If there is play (or
"backlash" if you want) in the ball crank - graduated collar - bushing area,
there is a proper fix that does not require shims. I have included the SBL
sheet on fitting a new cross screw with the instructions as an attachment.
These instructions are just as pertinent to fixing a screw that has a worn
thrust shoulder on the screw and/or bushing.

If one lacks access to a second lathe, the repairs can be accomplished on
the lathe under repair. For example if one is repairing the cross feed
screw, one removes the cross feed screw assembly (ball crank, collar,
bushing and screw) from the cross slide. Then one tightens the gib screws
on the cross feed slide to lock it in place. Then one can swing the
compound to "zero" or straight in and use the compound as the cross feed.
One doesn't need power feeds for this repair. After the cross feed screw is
repaired and replaced (and the gib screws are readjusted), the same
procedure can be performed on the compound screw assembly.

End play in the ball crank - collar - bushing assembly is common on these
lathes if they have any time on them. It is often confused with "backlash"
in the screw - nut fit and is easily fixed.

I hope this information is helpful. God Bless America!
- Blue Chips -
Webb

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