Arduino left and right motor ports unresponsive

Hi folks,

I’m new to Maslow and just got my kit … and I promptly broke it. ;(

I had the kit all together and had everything working. I used it to cut out my sled, moved my router over, re-calibrated and set it to run on a long project - making a sign. I had it running overnight and in the morning, the right chain was wrapped around the sprocket and nothing was moving.

I unwound eveything and attempted to recalibrate it. During motor/encoder testing, the left and right motors failed, but the z axis motor passed. So, I tested the left and right motors by plugging them into the z axis port and they pass.

So, did I burn out the Arduino? Do I need to get a new shield? Does something need to be “reset”?

Being new, I have the triangular link kit and the latest Arduino code and ground control.

Thanks for your help!

sounds like you burned out the motor controllers for the X-Y motors. Your arduino board should be fine, but you will likely need a new motor controller board.

Hi Keith,

Thanks for the response! Is the motor controller board the Arduino shield?


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Sorry about your predicament… I’ve had a similar experience when not paying enough attention to the machine during a cut run. It is to learn… Yes, the motor controller board where the motor cables plug in is probably damaged if the ‘Test Motors/Encoders’ test fails for the left or right motor. The Arduino board is probably still ok though.

Yep, that’s the one.

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Thanks blurfl!

What do you think is the root cause of the damage? Was it thermal on the board from the long run? Or because the motors didn’t respond?

Would a cooling fan have prevented the damage? Better alignment if the chain or a guard to prevent the chain from wrapping on the motor when unattended?

Thoughts on how to prevent it again?

I would guess thermal bc the motors were bound but likely still trying to move the sled, which would increase the motor electrical load to try to overcome the bind, thus running a lot of current through the motor driver chips ultimately resulting in magic smoke.

No way to know for sure, but if it had been caught early enough, and the motors shut off, the board may have survived. Generally speaking, leaching a cnc machine running unattended for any extended amount of time is not advisable.

Fortunately, it sons like your motors are done, so replacing the motor control shield should fix the problem. You’ll probably also want to examine the chains to see if they are twisted in any way, which might cause chain skipping or other feed problems.

Here’s hoping a new shield is all you need :slight_smile:

I think @Keith has summed up. You certainly need a motor driver board and maybe a new chain.
In my very similar instance, I decided that - “during unattended operation, a chain skip occurred which led to mechanical binding. That caused thermal damage to the chips driving the motors. The root cause was whatever caused the chain to skip.”
To prevent it from happening ending again,

  • I re-checked my setup for proper chain alignment and corrected that. Very careful checking the slack chain/sprocket/sled alignments showed that one of my motor mounts wasn’t as precisely mounted as it needed and the chain/sled alignment changed at different parts of the workarea because the plywood had bowed. I re-did my motor mounts more carefully and changed my frame to keep the plywood flat in both directions. I went through my slack chain arrangement to make sure the chain fed straight and tension was maintained throughout the working length.
  • I took the chains off and checked for twist and stretching I found that the one which had bound had and stretched about 1.5mm in total length, so I replaced it.
  • I lubed the chains with a dry Teflon chain lube.
  • Finally, I’ve tried not to leave the machine running unattended. The ‘Hold’ button is the tool for that, it finishes the current line of gcode then pauses until releases. A short break or quitting for the night, it will be in the same place and ready when I come back. I make a note of the current line number in GC just in case the computer has shut down GC - I can jump to that line and pick up again where I left off.

I chalked it up to learning. I don’t think a fan would have mattered nearly as much as being present to notice ‘something going on’. In my shop the Maslow isn’t yet a ‘fully qualified craftsman’ working alongside me, it’s a new apprentice that I need to keep an eye on, but that does pretty good work when things are going right.


Is a reasonable suspect. (no insurance will pay for anything like that or worse btw :slight_smile: )
What components have fried in that event is still to be narrowed in.
A one by one replacement would sound right for me.

I’m suspecting a power supply to have given up after 1 year use on the Maslow. Your event with shorts in the chips could have created an amp spark that would drive me to at least doubt my power supply or measure what it is still capable of.

Can you post your log file? Maybe there’s something in there that we can use to work on a ‘watchdog’ solution in firmware or GC that shuts things down when things go horribly wrong.

Ah! The hold button. That is a great idea. Thank you. I’ll look for the line numbers, too. I didn’t think of that to keep it from having to run unattended.

Yes, I think I need to make a slight adjustment to the alignment of my sprockets. There was slight rub marks on the crossbar in the morning, too.

I am chalking this upo to learning, too!

Thanks everyone for the input. I’ll get back on the horse as soon as the new shield comes in! :slight_smile: