RE: [Emc-users] Backlash (a different issue this time, I think)

[Donald V. L. <do...@sb...>]

   Hi Ben and Gene,

      It seems to me there are two possible problems. First would be if =
the
backlash was measured wrong, or if the program is doubling the amount of
correction, due to a mis definition of what the "backlash" is. Try =
halving the
value you are working with and see if this doesn't prevent the tool =
breaking.=20

      The way I have observed the EMC backlash compensation working, is =
that it
is applied when there is a reversal after a movement. The initial =
movement does
not have any quick action. If the proper amount of backlash is being =
applied,
then the axis should not move in the reverse direction at all while the =
quick
backlash compensating screw turning is happening. So, there should be no =
tool
breaking, because the work does not move.=20

       If there were too much compensation set up in the .ini, then the =
table
would move, and with more acceleration and velocity than set up in the =
.ini
file. With steppers, they would most likely stall at this point. But, =
the
residual energy in the magnetic field would rapidly accelerate the table =
a small
amount and crash the tool.=20

       The other problem could be that there is variable backlash in the =
screw.
Say the threads of the screw are thicker in one place, then another. If =
where
you measured the backlash, the screw threads were thin, then you would =
have more
backlash there. So, when a backlash compensation occurred where the =
screw thread
was thick, which would result in less backlash, then the tool would =
crash.=20

         73, Don...


-----Original Message-----
From: emc...@li...
[mailto:emc...@li...] On Behalf Of Ben Dugan
Sent: Thursday, October 27, 2005 3:32 PM
To: emc...@li...
Subject: Re: [Emc-users] Backlash (a different issue this time, I think)



Gene,

Thanks for your email.

So we'd both like to be able to slow down the backlash step, right?  I=20
think we're on the same page about that.

If I understand you right, though, you're also trying to improve the=20
leadscrew in your setup, which I think is a different issue.

Ben




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