Z table stepper stopped working under load

Machine: K40

Board: C3D Laserboard

Firmware: GRBL-LPC

Problem/ Question: A few days ago my lightobject z table stepping motor stopped moving the table up
or down, but does ‘buzz’ when a jog request is made. Occasionally it will move a few steps. I was able to get it working again by resetting (powering off and back on) the laserboard, but this was only good for a day or so. I tried to loosen the belt tension but this had no effect. I can get the shaft to turn only by removing the load entirely. I replaced the stepping motor but get the same results. Spins OK while in no load state but as soon as there is some load it just hums/buzzes. I have the gamma current already set at 1.2A in the config file. At this point I am thinking the output of the z driver is off. What would be the best way to measure current output of the laserboard driver, or do you have other suggestions?

Thank you

Curious if it will work with the A driver. Not sure how much weight you had on it, but you may want to think about an external driver.

There was no weight on the table. Just the light object table itself. When removed from table, you can easily stop the stepper motor shaft by pinching the shaft lightly. I have tried two different stepper motors and both react the same. Almost no pressure required to stop the shaft rotation. Will try the A driver

You state you are using GRBL-LPC firmware. GRBL-LPC is configured by using the Machine Settings in LightBurn (or via the $ commands in Console), no longer by the config.txt file on the board’s memory card like it was with stock Smoothie firmware.

You probably need to set the Z motor current to 1.2 via that method, as your symptoms would be explained by the motor current being too low.

It could also be a stealthchop vs spreadcycle stepper driver mode, or trying to move too fast. These will also be worth looking into if the above does not solve your problem.

I don’t have a LightObject Z Table so our guidance that it will work with the built in stepper driver has been based on other users’ experiences, but I don’t know how much weight they were trying to move with it.

I’d like to get you sorted here before dealing with “whether you need an external stepper driver” and amending or cancelling your most recent order with us.

You are correct. I found the settings this morning for the current in lightburn. I also disassembled and reassembled the ztable to be sure there was no binding. But I think it was setting 1.2A in the lightburn settings that made the difference. Thank you for your responses!. Please cancel my order for the
external stepper cables, I (thankfully) won’t be needing them.


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