Which stepper motors are compatible with the laser board?

Machine: K40

Board: Cohesion3D laserboard

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

Problem/ Question: I bought a used K40 with a toast moshi MS10105 board. Just ordered a cohesion3d laserboard but in the meantime installed an Arduino MEGA with ramps and 2 A4988 drivers.
I cannot get the steppers to work well, they are skipping and jumping. Adjusted Vref to 0.24V based on a sketchy Google search for 42-2100C08S (Y) and 42-2100B03 (X) which had them vaguely rated at 0.6A for step current. I suspect that there is an issue with the steppers themselves and considering preemptively ordering new stepper motors (as an upgrade as well). Which stepper motors (or specs thereof) work well with the cohesion3d laserboard? The one in the store is only single shaft so it won’t work for my Y axis. I couldn’t find any info on what stepper motors are supported by the board.

The LaserBoard will support any biphase NEMA17 motor that specifies current up to 1.2A RMS. K40s usually ship with 0.9° motors as opposed to the more common 1.8° motors - it is a good idea to match that specification to avoid additional configuration overhead.

After doing a quick google search for these motors, I’m unable to find any definitive information - I find a lot of conflicting specifications for them. Tuning current for stepper motors can be tricky. Start with 0.6A, then increase the current by 0.2A at a time until you get reliable operation. Ensure the motors don’t get excessively hot after a few minutes of operation - they can and will be warm to the touch but you should be able to hold on to them comfortably. If it is uncomfortable, they’re too hot and you need to back off the current.

Another thing to check if you’re missing steps is the mechanical connections: check the belts. Are they tight? Are they too tight? There should be some slack, but not enough to where it makes the belts difficult to move. The gantry and rollers should be free-rolling and lubricated with a small amount of white lithium grease. Frozen/worn rollers and carriage guides should be cleaned/lubricated/replaced as necessary. Any bearing surface should be lubricated as well.

Good luck!

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Stepper motors very rarely fail. “Skipping and jumping” does not mean they have stopped working. The K40 uses very specific motors: 0.9 degree and the Y axis one is a dual shaft. These are not easy to find in that combination.

The preferred answer is to leave everything alone and swap the LaserBoard into as close to a stock machine as you can.

Yeah - I can definitely say that in all my searching, I have not been able to find a higher-torque 0.9° dual-shaft NEMA17 to replace the one in my K40. The one I have works just fine, though - I had wanted to increase the gantry weight by adding some drag chains and stuff to clean up the wiring/hoses (which proved too much for the stock Y motor) and couldn’t find anything suitable. I ended up ordering, about six months ago, (and haven’t yet installed due to lack of time) a 1.8° equivalent. I’m not looking forward to the recalibration I’m going to have to do.

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