re:Re: backlash testing

Hugh,

I'll buy that! And I'll add...

Backlash can be found occurring beyond the nut/ screw interface! The
leadscrew may be shifting axially in its' mounts. A motor belt drive
may have backlash also. Or 'cyclical errors'(out of roundness).
That's why Fred S' idea to check backlash at a "system level" is a
good one, IMO.

I'd add to HIS comments: Be sure to check backlash THROUGHOUT the
travel(s). Also use movements of more than one inch when 'fine
tuning'. As I said, we're interested in the "system" backlash, not
just the screw/nut!

Hope this helps.

Ballendo

P.S. inserting "extra" backlash values in software can make some
interesting patterns. Try 1/2 inch b/l comp on a circle, for example.
While you're 'playing', try inserting "incorrect"/ unequal steps per
unit. Turns circles into ovals, or "squishes/expands" text to fit
horizontally, vertically! BE SURE TO RESET things when you are 'done'
playing!

And you can "scale" toolpaths by "lying" to the control about
stepsize. Even accomplish "roughing cutpaths" on SOME TYPES of
parts...(lie about z steps per unit)

>Tauseef & all:
>As I understand backlash it is the slop or free-play between the
>lead screw and its nut. In moving right, stopping, then moving left
>some lead screw rotation is needed to take up the slop and thus
>doesn't move the table. This rotation without table motion is
>backlash?<snip>
>Hugh