Z stepper motor overheating

Machine: K40

Board: Laserboard

Firmware: “I have a new board and I’m using whatever it came with”

Problem/ Question: I have a Z table in my K40 and have it attached to the Z axis on the Laserboard and it is rated for 1.7a so I have it set to 1.2 in the config based on this chart.

Should it be getting so hot that I cannot touch it? Is there a way to disengage the Z Axis in between move commands that it will not be powered up all the time. I rarely raise or lower it so there is no need to keep the motor energized all the time so that it gets hot.

This is the motor I have on the Z axis.

The motor should be engaged all the time to hold the table in place during a job. Since the machine bumps about when the gantry is in motion it’s definitely likely that Z will be affected during a job if the stepper’s not locked.

That said, something’s definitely wrong if your motor’s getting too hot to touch, and that likely means overcurrent. The spec sheet for your motor does indeed say 1.7A, but if it’s getting hot like that the motor may have been mislabeled at the factory or something. Back it off to 0.8A and check two things: a) the table moves the commanded amount without losing steps b) the motor doesn’t get hot like that. It’s OK and normal for them to get warm, but you should always be able to touch them continuously without turning your fingertips into seared flesh.

I changed it to .8 prior to your post just to see and it still seems to get warmer than it should just sitting there.

Did you let it cool completely before applying power again?

Yes I did, sat overnight and tested again and it get hot pretty quick. I tested this same motor on 2 different CNC Shields and had no overheating issue.

OK, let’s try something else - in your config file, let’s move your Z axis to the A connector and physically move the wires from Z to A. You will need to swap the gamma_step_pin, gamma_dir_pin, and gamma_en_pin values with the ones for the delta axis and vice versa. Then, use delta_current to set the appropriate current value for this motor.

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