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Backlash Problems
« on: December 24, 2013, 06:08:03 AM »
I am having a strange issue with Mach3 backlash compensation.  I am using a 4' X 6' router.  I am using steppers and Lead shine servos with 90V AC power supply (2 X 240V AC transformers).  Max speed of the machine is 10,000mm/min.  It works fine at that speed.  Manufacturer rates it a twice this.  The machine works absolutely fine with backlash compensation turned off.  I have no problems with correct travel or simultaneous moves of the axis.

If I move one axis at a time (X, Y or Z) everything works as expected with the backlash compensation enabled.  If I try to move any two axis concurrently there is no problem as long as I move in such a way that backlash compensation is not activated.  If I move in a manner that enable backlash compensation the machine clunks, drops steps and (occasionally) squeals.    

I am trying to surface my spoil board and, by the end of the surfacing operation I have lost ~3 inches in X.  Repeat with backlash compensation of and there is no clunking and the machine works as expected.

e.g. I can replicate is I start the y axis moving in one direction continuously and whilst it is moving, I move the x axis or z axis one way, then the other (say 2 seconds in either direction).  Even if the x/z axis is stationary but Mach3 determines that it is a change in direction from the last move, the axis will lock up.

Changing motor speeds and acceleration makes no difference.    I have tried backlash settings of 50% of max, as well as 20, 10, 5, 1.  All has no effect.

My backlash settings are very small for each axis:
X  0.030mm
Y  0.055mm
Z 0.035mm

I confirmed Constant Velocity mode is turned on.

I am using Mach3 R3.043.066 (Latest) on Windows XP and the software is registered.

Can anyone help?
« Last Edit: December 24, 2013, 06:12:13 AM by swarfmeister »

Offline Hood

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Re: Backlash Problems
« Reply #1 on: December 24, 2013, 06:15:17 AM »
Try adjusting the shuttle Accel (General Config page)
Hood
Re: Backlash Problems
« Reply #2 on: December 24, 2013, 07:17:12 AM »
Ok, So I was able to adjust the shuttle to between 0.1 and 0.25 seconds.  The clunking is gone.  I left it at 0.25 to be safe.  I think it may have fixed it.  Except for the 0.25 second pauses every time an axis changes direction.

The question is why?  Lack of power from the power supply?  Noise in the system?  Mach3 software? Something else?
Re: Backlash Problems
« Reply #3 on: December 24, 2013, 09:13:04 AM »
Sounds a bit you using an external controller, can it handle the backlash compensation correct ?

just a thougt

alex