SKR 1.4 turbo dual X configuration (X motor low holding power)

Dear all,

I would like to ask for your assistance with the SKR 1.4 turbo board (5xTMC2130). I want to run a cnc machine (RPI controlled over serial).

Previously I was running the configuration with X axis instead of Z where I used two sockets for X and X2 motors with one driver. However, I was disappointed with the accuracy (GT2 belt 1200 : 1200 mm system). I have read that going to separate drivers might help. However, I stumbled up on some issues.

In the setup - with belts.
I have 2 motors for X coordinate. Y and Z single motor work fine (I also use bl touch - works fine). I enabled X2_DRIVER_TYPE and SPI mode. M119 list all endstops as open (for now I have only one endstop for X, other for X2 is disabled - tried with it enabled, did not work) and M122 List all 4 motors (no errors). When I run G0X10 command only one motor (X2) moves. Directly after G0Y command, when moving the X and X2 by hand it seems there is very little bias applied on the X motor (unplugging the cable makes the movement easy). X2 on the other hand is rock solid. Could you please advise how to solve this?

No belts, motor spin free:
Both X and X2 work, however holding power of X motor is significantly lower.

I have 12V power supply supporting 20A.

I tried swapping to Y instead of X (same problem). I tried to move around the drivers in different sockets (same problem).

Eventually I would like to redefine E1 as a rotation stage too (I_DRIVER_TYPE). That worked for me in the past but in this setup I got extra errors.

Thank you a lot!

dual x is not going change anything accuracy wise.


When you enable a driver type X2 marlin auto allocates the first unused E as X2, so the first X is plugged into X plug and the X2 is plugged into E0 or E1 plugs (what ever is still un allocated) (unless you have changed the pins files to explicitly define the X2 pins)

Thank you for a quick response.

I still do not understand why having same system (same belt tension and V wheels) works better (similar hold power) when one driver (Z) is used for both motors.

For current configuration I did not redefine any pins. Now X2 is plugged into E0.

To compensate for low holding I cannot swap my V wheels but I can reduce the belt tension.

I finally found the issue, pulley of the motor was loose due to continuous runs before ...

Any suggestions how can I fix them better to the shaft?