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Unusual Slave axis problem
« on: September 09, 2015, 05:31:40 PM »
I'm having a rather odd problem with mach 3. I have a plasma table running cuts well most of the time however occasionally when I start a cut the slave axis and x axis do not move in unison. its a fairly aggressive switching one motor to the other. this only happens right when I start a cut. I could jog the table back and forth all day and it would never do it. the real interesting part is that I can jog the machine normally immediately after this has happened without resetting anything. It seems to me this problem must be tied into the software somehow. does anyone have any thoughts?

I am using a probotix PBX with probotix steppers and Keling Technologies KL-4030 stepper motor drivers 


Offline ger21

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Re: Unusual Slave axis problem
« Reply #1 on: September 09, 2015, 05:45:47 PM »
Is there interference  when the torch fires? That's what it sounds like to me.

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Re: Unusual Slave axis problem
« Reply #2 on: September 10, 2015, 12:38:10 AM »
I don't believe so.. I have actually now had the issue happen while jogging the machine. I thought I found the reason for the issue, previously I was driving the X and A axis from the same output on the PBX. (DIR+ and PUL+ was a shared signal running to both X and A axis stepper motor controllers) However, I have now changed this to it's own independent channel for X and A, figuring the signal from the PBX was to weak to supply both controllers. Unfortunately the same issue showed up shortly after I made the change. All of the cable on the stepper motors are shielded and grounded. The wires are secured to the opposite sides of the cable trays from the torch to maximize distance to reduce the risk of interference. The issue seems to occur frequently as the machine is trans-versing to the cut start point before the torch is ignited. 

on an unrelated note I have noticed when the machine is leading in on a cut it accelerates very suddenly regardless of what I set the acceleration rate this is affecting the quality of circular cuts is there any way to slow this down?

thanks for the help!
Re: Unusual Slave axis problem
« Reply #3 on: September 10, 2015, 12:43:07 AM »
oh and I should mention there is basically no chance it is a mechanical issue with the table. The whole table is built by a real German Machinist and he is an absolute perfectionist. It's been in the works for about a year now he did a REALLY nice job :)
« Last Edit: September 10, 2015, 12:45:24 AM by maxvw »
Re: Unusual Slave axis problem
« Reply #4 on: March 30, 2016, 10:10:03 AM »
I'm also having a problem slaving the A-axis with the Y-axis. 

My original driver failed and upon replacing it noticed that it had been set-up with two stepper motors (Y-axis) being driven by a single driver.   Some research identified that each driver should have a dedicated driver, therefore I
replaced the single driver with 2 new drivers and re-wired.
In Mach 3 I selected Slave Axis and slaved 'A' to 'Y', then re-started Mach 3 as instructed
I have ensured that motor outputs are enabled for the A-axis, the motor tuning is identical for both motors and the A-axis is not inhibited (in Settings)
I have tested the stepper motors and each works so there is unlikely to be an issue with the wiring or drivers

I cannot seem to make the slave (A-axis) stepper motor work, i.e. when I select and jog the Y-axis in Mach 3 only one motor turns.  Maybe the Motor Output numbers (Step Pin and Dir Pin) for the A-axis are incorrect?

Any help would be massively appreciated...