New K40 upgrade with motion issues

Machine: K40 with original board

Board: Cohesion3D LaserBoard Added 5amp 24vdc power supply

Firmware: Smoothie

Problem/ Question: Jerky X and Y. Y seams to start working after a bit and operates smoothly (no mechanical binding on either axis). M119 shows optical end stops are working as expected (1 for triggered, 0 for un-triggered)

I have built several CNC machines in the past, router and X2 metal mill conversions but have never used this controller/driver config. Mach3 and a parallel BOB.

I have made some changes to the config.txt file from some suggestions on the Forum.
Current, acceleration, max speed ect…
I will try attache some pics, video and my config.txt but need to read some directions on the Forum

Thanks for any assistance


Pull up a data sheet for your motors and compare them to your configuration settings.
Second using your data sheet look at the coils on your motors and make sure they are wired correctly .
Generally coils are paired A+ and A- one pair B+ and B- second pair or A1A2 B1B2.
You can check coils without a data sheet by reading the impedance across the wires. or by twisting 2 wires together and see if the motor becomes hard to turn.
If your settings are correct in the config file and the wiring correct (check your plugs continuity to make sure they are working properly) then start looking for noise interference.
the best way to do that is by using shielded cable if you do make sure to only ground the shield on the board side. do not ground it to the motor the motors create noise the idea is to isolate the cable shield from the motor. the motor is probably mounted on metal that is grounded. connecting the cable shield to both the board and the motor will create a ground loop.
If your stepper motors are way to long shorten them.(if you have like an extra 12 inches laying around in your electronic area)
Separate your wires running multiple non shielded steppers wires side by side can induce noise into each other .
Running your motor wires close to AC lines can cause noise.
for testing purposes you can create a faraday cage around one of your wires to see if its succumbing to noise.

Thats all i can think of right now
Hope it helps

Thanks for the reply!! I found the board connector to be bad. Used the screw terminals and works great now. Next step is to put some grub screws on the bed cage to align it better, then about 50 other things, great fun, great group.

Thank you again!!


… Can you elaborate on this, preferably with details and pictures so I can see what is being discussed?

If there is a missing solder joint or clearly visible board defect, I definitely want to know about it.
Otherwise, what does happen is that the JST XH and VH style header contacts often have the pins that don’t seat all the way in so people have bad electrical contacts leading to jittering but not moving motors and a laser that won’t fire.

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