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Author Topic: Cannot get backlash to work.  (Read 1964 times)

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Cannot get backlash to work.
« on: November 24, 2012, 12:26:02 PM »
Hello, I cannot seem to get backlash comp to work at all. No matter what values I use it makes no difference. Speed is set to 200%. Tried .003" and nothing. Then tried .050 and no difference. Each time I make a change I close and open Mach and check the values before moving but there is no comp happening. Any settings I am missing?
Thanks

Offline Fastest1

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Cannot get backlash to work.
« Reply #1 on: November 24, 2012, 01:04:22 PM »
So are you saying when you go back to verify the changes, they aren't where you set them? Or the changes are not being performed? I would think the 200% is definitely the wrong way to go. 100% is the rapid or velocity setting of your motor tuning. You can not exceed this setting. I have always used values of 50-100%. This is only in regards to the speed at which Mach takes up the backlash. Since you are attempting to use values above an attainable speed, I wonder if Mach is disregarding your request?
I want to die in my sleep like my grandfather, not like the passengers in the car! :-)
Re: Cannot get backlash to work.
« Reply #2 on: November 24, 2012, 01:12:52 PM »
I mean Mach shows the setting in the backlash configuration box but does not execute them. I originally had speed set to 20% and after reading some of the posts in here i changed it to 200%. I tried 50% and still nothing. It's like it just ignores whatever backlash I put in.  And yes backlash is enabled.

Offline RICH

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Re: Cannot get backlash to work.
« Reply #3 on: November 24, 2012, 08:24:27 PM »
AMorris,
See if this helps"

The  50-50-50 rule which you may want to consider is as follows:

50% - The max velocity is 50% of where your steppers will start to skip
50% - Set the shuttle Wheel setting in configuration to .0050  to .050 ( .5 too slow )
50% - Backlash speed

The Shuttle Wheel Accel is in seconds. How exactly is the" time" applied to the backlash "cycle"? Well I don't really know.
 It's internal to Mach. By observing the difference in how the motor reacts to different settings you will see that it affects the overall time
 it takes for Mach to take up the backlash and at say a value of 5 you will find that over five seconds the handwheel / shaft will turn
 rather slowly. At 0.005 sec its almost instantaneous. In the real slow setting, and say you jog a distance of .1"  you will find there
seems to be almost 3 distinct motor responses in the cycle,....... a small rotation then deceleration...... then backlash taken up
over a time...and then  accel and move to finish the distance.

So to get of flavor of it you need to start slow, observe, listen to see what is happening over an operating range.
Work your way up in settings.

RICH