Can C3D Laserboard drive 2 stepper motors on Y-axis for new K40 gantry?

Machine: K40

Board: Laserboard

Firmware: Smoothie

Problem/ Question: I’m replacing the OEM K40 gantry with a larger one. The design requires 2 stepper motors for the Y-axis. I plan to use 1.68A (peak) motors. I connected the left motor for the Y-axis and all is well (using Lightburn to control things). However, when I connect the right motor, the motors turn together in the correct direction for movement, but there doesn’t seem to be enough power to drive them both. I’d like to know how to get past this hurdle. I’m hoping it’s just a change to the Smoothie configuration file, but I’m not sure in which direction to proceed. I would very much appreciate some guidance. Thanks!


I would first of all suggest using an external stepper driver. This way you can safely run far higher power through your motors - especially when running two side-by-side.

And yes, it is doable to run two steppers of an external stepper driver. You can either run them in Parallel or in Serial setup, and from an electrical standpoint the last seems to be the most logic - since in serial setup the Amps are equal in both motors, while the voltage is divided. A stepper is Amps driven so that should make more sense.

In a quick Google search I found several forums / setups for CNC’s, 3D printers and lasercutter selfbuilds using similar setups and also found the following serial wiring setup:
As always, pay attention when wiring these kind of components and test well before everything is blown to bits due to a wiring or config mistake :slight_smile:

Thanks for the reply. I’ve been reading more about this and it’s often suggested to use a single motor with a drive shaft for the other side of the Y-axis instead of two motors. The issue is that, with a CO2 laser, there’s a danger if one of the two Y-axis stepper motors fails sending the laser beam in unwanted directions. It seems like a reasonable precaution so I can always redesign my gantry in case two motors turn out to be a bad idea.

Agreed that it’s a bad idea to have 2 separate Y motors for a CO2 gantry - if they get out of whack you are screwed. A single motor with a shaft driving the Y rails on both ends is the way to go.

For reference, it is possible to set up the LaserBoard to drive 2 Y motors off 2 separate onboard drivers for diode laser and CNC use. This is a documentation article that is in the works now.

This topic was automatically closed 14 days after the last reply. New replies are no longer allowed.