Help me setup Marlin FW for MKS board for dual extruder?

I have a MKS gen 2z v1.1 board

I want to have two extruder-steppers and only one z-stepper, I'm new to marlin/arduino but i feel like I've tried changing every single setting in Marlin.
No matter what i try both steppers acts as z-steppers (when i move z axis both steppers move)

can someone please help me, how do I make it possible to have two (individual) extruder steppers?

from the name, Im guessing this board has the same step/direction/enable lines from Z going to the two stepper drivers.

Ie its not possible to over ride this behavior in firmware, you have to actually modify the circuit board.


got a multi meter? we can test this

with the printer off and usb unplugged (ie making very sure its off with no power)
check continuity from the step pin on Z1 to the step pin on Z2 if they are connected. your out of luck.

there's continuity... I've wasted a LOT of time.
thanks for your help! I need to buy a new board.

but what's the point of having the same signals going to both z drivers? couldn't they just have used a single stepper driver to run 'em both then?

with this configuration both Z steppers get the full current of each stepper driver.

When steppers are in parallel on one stepper driver they each get half the current (presuming the steppers are identical)

Edited 2 time(s). Last edit at 08/27/2018 09:11AM by Dust.

ahh that makes sense, can I theoretically connect both drivers to one motor and then use a bigger stepper motor then? - just wondering

Dont know, not something I would want to try...

The signals coming out of a stepper driver are complicated and if one is slightly out timing wise the energy is probably going to go into the other driver and damage it.

ok I'll just forget it then, either way... I'll better be looking for a new board capable of running two extruders. thanks for your help!