Z-axis. drivers failed in a short time

Hello,

I have the following configuration:

MPCNC: 1000x900x250mm (X,Y,Z)
MKS RUMBA+
DRV8225
NEMA 17hs19-2004s1
POWER Supply: ?V , ?A
MAKITA RT0700C (710W, max. 30000 revolutions no-load)

FIRMWARE:
Marlin 2
the customized version
“Marlin-MPCNC_Rumba_T8_16T_LCD_32step_DualEndstop”

The milling machine is newly built. A few test runs worked without any problems. Now I have a problem on the Z-axis. Three drivers failed in a short time. I used a 35mm planer cutter with 600mm/s with 2mm acceptance from oak. All drivers are set to 0.8V. The last one I had set as a test to 0.4V. I also measured the motor, it has about 2 ohms per phase. The Z-axis is easy to move. The threaded rod is straight.

The Z-driver didn’t get hot either. Nevertheless it is broken and does not supply power anymore.

Yesterday the ordered new drivers arrived. What can I do now to find the error?

Any ideas?

Greetings Bastian

Try getting a real pololu, I bet it doesn’t pop!

Other than that you say0.8V but you do not list the power supply voltage. We can’t proof the numbers without that.

Just guessing since its hard to really know, but bad wiring can produce an intermittent connection and this can kill stepper drivers. Would you describe your Z wiring as “solid” or “janky” or something in between?

It is hard to kill drivers from overloading them. High torque and the motors skip and the driver feels nothing. High current and the thermal shutdown starts cutting power to your motors, which can be murder for your workpiece but your driver will be fine.

Good call, If you unplug or have a loose wire on a cheapie board you driver is the first thing to die. Newer boards have more protection against this.

I soldered the ends of the motor with Ethernet cable. I just remembered that in contrast to the X Y axes I soldered the twisted pairs of wires (always two) to one motor cable. As a redundancy idea. Maybe that’s the problem.

Is driver death impossible if the motor loses steps under high mechanical load and the axis is pulled down? I asked myself the same question.

Immediately after the failure I put my finger on the heat sink. Lukewarm.
I also read that the drivers switch off when overloaded. My question: When will it be reactivated? When rebooting the machine?

I will rewire the Z wiring in the next few days. Thank you very much for your promising advice.

Apparently, the problem’s solved. Since I replaced the cabling the driver is still working.

However, I also have another driver from an alternative source.

Thanks again for your support.

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