Im a member of a new makerspace that recently acquired a used chinese laser cutter from somebody who needed the money. The laser tube is supposedly 150w and it has a cutting area of 1300x800mm or there abouts. The controller is a RDC6332M and for the most part things seems to be working.

after cleaning the machine and re-aligning the mirrors it seems to cut and engrave just fine and it has no problems drawing straight lines or even curves as long as you are going slow enough. but if you bump the speed up a bit everything goes to hell in a hand basket.

when trying to engrave curves at like 100mm/s it seems unable to follow them instead under and overshooting creating really ugly shapes. While trying to trouble-shoot this issue we found that if you set the move speed to 200mm/s on the machine and jog 2 axises at the same time. 1 of the axises will jam up and/or make a horrific noise. This happens when running XY. XU or UY.. as long as you are moving slowly. or only moving 1 axis at a time. everything is fine

while it is doing this it is also losing steps. rather a lot we took this video just before going home tonight. in it we are jogging the X and Y axis at the same time..
in it the X axis gets mis-aligned by 100mm.


Things we have tried:

  • Lubing the rails with lithium-grease.
  • Disconnecting the stepper drive belt so that the rails are only running their regular drive belts and then checking for resistance or lack of paralellism. (nothing obvious found)
  • Checking the Power supply for brownouts using a multi meter at both at the stepper driver and at the power supply. (steady 40.1V at both ends)
  • Tried adjusting the settings on the stepper drivers to give less current (thinking maybe the PSU wasnt providing enough juice)
  • Tried adjusting the settings on the stepper drivers to give MORE current. (thinking maybe the steppers werent getting enough juice.)


So far all we found is that there might be a little bit of drag on both axises in some spots.but nothing that we couldn't easily push past with just a tiny bit extra finger pressure and they generally went away once we lubed it.

None of us are experts in building or trouble-shooting laser cutters. and this isn't helped by the fact that we got it second hand by somebody who might have done something idiotic with it.

So far all we have is that we could try swapping the PSU or that we could try messing with the USER and MACHINE parameters for things like steps and acceleration but we have no idea what would be sensible figures to start with in that department.

Any suggestions for troubleshooting steps to try or sensible things to try and look at in the machine parameters would be much appreciated.

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