Help setting up MegaPi with two Z stepper motors

#1

I’m converting my i3 Prusa 3D printer to a laser machine. I’ve removed all the 3D hardware and now just have the frame with one X stepper, one Y stepper and two Z steppers.

I have the Marlin RC8 source firmware so I can go into that and setup the needed #defines but I don’t what file or which #defines I need to modify.

I’m assuming I can plug any stepper into any one of the four ports and I tell the MegaPi which steppers are plugged into which ports via the #defines in Marlin?

I notice on my laserBot, the X and Y steppers are plugged into the outer two ports and the inner two ports are unused.

Thanks for any help…!!!

#2

I uncommented the line in adv.h

Z_DUAL_STEPPER_DRIVER

…but got a compiler error: pins.h:449: error: ‘E1_STEP_PIN’ was not declared in this scope.

Does anyone know how to resolve this?

Thanks…

#3

Hi rfresh737,

This is John. I wanted to post here what we found via email exchanges in case it helps anyone else looking to run two stepper motors on the Z axis.

What we found was that the Marlin firmware is expecting an extruder to exist which means that the first available stepper port (E0) is automatically assigned and when you enable the Z_DUAL_STEPPER_DRIVER flag, it assigns the next available port which is E1. The pins_file for the megapi board has X, Y, Z & E0 defined so that it will compile. However, E0 is not actually available to be used since the firmware expects an extruder motor to be assigned to that.

Note: setting the extruder count to 0 will cause it to fail when compiling the code, so it does not appear to support disabling the extruder.

Hope that helps someone out.
Thanks
John

#4