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phamandp
09-08-2018, 10:37 PM
Hi everyone! I have a problem with my CNC controller setting ( I use Planet CNC USB Controller Mk3). My CNC machine have 4 axis ( X axis set axis 1 port,Y axis set axis 2 port ,Z axis set axis 3 port, A axis set axis 4 port and A slave axis axis 5 port) and I drive them by stepper motor. X,Y,Z axises are good moving but A axis seem to be missing step. I have already changed A axis from port 4 to port 6,7 on my controller but the result is the same for all case. When I tried to use axis 1,2,3 port for A axis the missing step problem not anymore. I have already tried some time but nothing change. My setting file is below. Someone can please to help me? Thanks a lot.
https://drive.google.com/drive/my-drive?ogsrc=32

harryn
09-23-2018, 02:04 PM
I don't have a google account for privacy reasons so I cannot look at your configuration.

If you can post the info directly into the forum I will take a look.

Probably it helps if you have some information posted with the details of your stepper motor, gearing, etc because usually if a cnc is missing steps, it is a torque problem.

Since a stepper motor is a constant power device, and power = torque x rpm, try slowing down that axis fairly dramatically and see if that helps.

phamandp
09-24-2018, 10:24 AM
I don't have a google account for privacy reasons so I cannot look at your configuration.

If you can post the info directly into the forum I will take a look.

Probably it helps if you have some information posted with the details of your stepper motor, gearing, etc because usually if a cnc is missing steps, it is a torque problem.

Since a stepper motor is a constant power device, and power = torque x rpm, try slowing down that axis fairly dramatically and see if that helps.

Thanks you harryn,
About my A Axis rotary configuration:
+ Driver Vexta RKD514H-C set at 0.18 deg./step and 1.4A current.
+ Motor Vexta PK596 with 0.0144 deg./step resolution 1.4A current max and 2N.m torque max.
+ Gear ratio 3:80.
+ Mass of rotary mechanism: 23Kg
I don't know reason why sometime it working nice sometime missing step.
My setting is below. Please see attached.
402718
https://www.cnczone.com/forums/attachment.php?attachmentid=402722&stc=1https://www.cnczone.com/forums/attachment.php?attachmentid=402724&stc=1https://www.cnczone.com/forums/attachment.php?attachmentid=402720&stc=1

harryn
09-25-2018, 12:22 AM
First - I only have recently started to work with the planet cnc product, so I am a beginner in that area.

I have some experience with the motor similar to that one. My understanding is that it is a 5 phase motor, so the step size is not the same as a normal stepper motor. In a conventional stepper motor, it uses 200 steps per rotation and relies on using micro stepping and gearing for finer resolution. The motor you have (I think) is intrinsically finer steps, so you don't want to do micro stepping with them.

I have some older versions of that motor and they came each with a anti vibration damper on the shaft. I don't entirely know why, but with the vibration damper, they worked pretty well. If the vibration damper was removed, they sometimes would go into oscillations and not work right.

harryn
09-27-2018, 02:13 PM
Another question - the stepper motor is only 1.4 amps? What voltage are your feeding into the driver? I am assuming fairly close to the maximum?

I am not an expert, but this seems like a very small motor for a 23 Kg rotating table.

It is not at all clear to me why you are loosing steps on some axis vs other. Perhaps find someone with an oscilloscope and have them look at the wave form profiles coming out.

phamandp
09-29-2018, 10:27 AM
Another question - the stepper motor is only 1.4 amps? What voltage are your feeding into the driver? I am assuming fairly close to the maximum?

I am not an expert, but this seems like a very small motor for a 23 Kg rotating table.

It is not at all clear to me why you are loosing steps on some axis vs other. Perhaps find someone with an oscilloscope and have them look at the wave form profiles coming out.

The driver with adjustable current from 0.25-1.4A and it was supply 220V Voltage. You right! the motor seem to be overload even though I use gear box with 3:80 ratio. About losing steps on some axis I will try as you suggestion. Thanks for your help! :)