commandcnc linux motor issues

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mcmental
Posts: 42
Joined: Thu May 14, 2020 10:06 am

commandcnc linux motor issues

Post by mcmental » Tue Sep 14, 2021 2:54 am

hi there, i have asked the question on the commandcnc forum but i dont seem to be getting a clear answer.

i have a 4 motor setup for plasma and im running commandcnc on linux, now everything was running fine except i had my home switches in wrong place so i moved them and re routed some wiring, upon switching everything back on now when i try to run the Y axis (this has second motor as a slave) i just get loads of juddering and it doesnt go anywhere, i have put 1 motor into reverse (still using the old settings) so i switched the wiring for the 2 motors and then the problem goes to the other motor, swapped the drivers over still have the issue.
i have taken the belts off so i can see what is going on and only 1 of the motors drives when i hit the jog key on the keyboard, should they both drive?? couple of videos here, 1 with both motors connected and 1 with only 1 connected.
only reason i have it as motor 5 not 4 is because of a chewed up screw on the terminal.
thanks


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mcmental
Posts: 42
Joined: Thu May 14, 2020 10:06 am

Re: commandcnc linux motor issues

Post by mcmental » Tue Sep 14, 2021 3:04 am

the settings are showing 800 steps per unit at the moment i have put those up to around 2000, im working in metric here in the uk, nema 23 steppers 20 tooth gear and gt3 belt.

robertspark
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Re: commandcnc linux motor issues

Post by robertspark » Tue Sep 14, 2021 3:22 am

mcmental wrote:
Tue Sep 14, 2021 3:04 am
the settings are showing 800 steps per unit at the moment i have put those up to around 2000, im working in metric here in the uk, nema 23 steppers 20 tooth gear and gt3 belt.
??

I don't understand your math.

800 steps per inch equals 800 steps per 25.4mm....
therefore 800/25.4= 31.4960629921 steps per mm

20 tooth gear... gt3 (1 presume 3mm per tooth???)
sw5-sw8 on on on off = 1000 micro steps per rev

20 X 3 = 60mm per revolution.
60 / 1000 = 0.06mm / step
1/0.06 = 16.6666666667 steps per mm

if in imperial....
16.6666666667 X 25.4 = 423.333333333 steps per inch....

mcmental
Posts: 42
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Re: commandcnc linux motor issues

Post by mcmental » Tue Sep 14, 2021 3:42 am

robertspark wrote:
Tue Sep 14, 2021 3:22 am
mcmental wrote:
Tue Sep 14, 2021 3:04 am
the settings are showing 800 steps per unit at the moment i have put those up to around 2000, im working in metric here in the uk, nema 23 steppers 20 tooth gear and gt3 belt.
??

I don't understand your math.

800 steps per inch equals 800 steps per 25.4mm....
therefore 800/25.4= 31.4960629921 steps per mm

20 tooth gear... gt3 (1 presume 3mm per tooth???)
sw5-sw8 on on on off = 1000 micro steps per rev

20 X 3 = 60mm per revolution.
60 / 1000 = 0.06mm / step
1/0.06 = 16.6666666667 steps per mm

if in imperial....
16.6666666667 X 25.4 = 423.333333333 steps per inch....
Thank you, the original settings vanished during a power cut so I was guessing. So should the slave motor drive too?

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acourtjester
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Re: commandcnc linux motor issues

Post by acourtjester » Tue Sep 14, 2021 11:25 pm

if you have 2 motors on one axis they need to have the same setting on the driver.
Now the jitter you have a broken wire or bad connection going to the motor that jitters, it is the DIR signal. What happens is it gets a step pulse but does not know which way to go, so it jitters.
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mcmental
Posts: 42
Joined: Thu May 14, 2020 10:06 am

Re: commandcnc linux motor issues

Post by mcmental » Wed Sep 15, 2021 12:28 am

Thank you, I have traced it back and found the wire at fault, going to work on the acceleration and velocity tonight

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