I used this bracket to convert the original V-King design to a three motor Z-axis with true auto-leveling of the print bed.
To convert the print bed, you need to print one more set of parts for the Z axis idlers/anchors. This bracket works with the existing Z belt anchor low to make it easy to convert. With those parts, simply mount the three motors and setup the three Z axis assemblies.
I am using a Duet Maestro and the M3D Duet Maestro breakout board to control the 3 motors. With this configuration, you can setup the motor drivers and the location of the motors like:
M584 X0 Y1 Z2:5:6 ; three Z motors connected to driver outputs 2, 5 and 6
M671 X28:273:156 Y480:480:-38 S0.5
And the following bed.g:
G1 X77.5 Y288 F12000
G30 P0 X77.5 Y288 Z-99999
G30 P1 X232.5 Y288 Z-99999
G30 P2 X154 Y72 Z-99999 S3
You can then run G32 to run the bed leveling. You should probably level the bed when it preheated to your normal print temperature (or average of your common print temperatures).
Note: The S0.5 parameter defines that only a maximum of 0.5mm of correction will be applied. If your bed is initially more out of level than 0.5mm then you can temporarily change that parameter or manually adjust the Z axis by driving each motor independently to get close to level before running a final G32.
Openscad source code is available: