How do I synchronized x-axis motors?

[Uli]

Dear Community,
we are currently setting up a Farmbot Genesis in the school where my wife works. When checking x-Axis moves we realized the gantry gets stuck for one to two seconds when moving over the middle of the raised bed (happens only in one direction). I have not checked if the raised bed is perfectly rectangular, but I noticed the two x-axis motors do not start spinning at the same time, there is a lag of about 1 second when they start. I assume that therefore the gantry is slightly angled when it moves along the guiding extrusions. Anybody noticed this as well and is there a way to fix it ?

[Darksplat]

Sounds like that the rails are not perfectly flat at the mid point. You need to adjust the rails so that they are perfectly flat so that the motors have no dramas in going down the whole track. If you can’t get any more adjustment from the rail as if you can’t push up or push down a rail or both to make them perfectly even get some sand paper and sand them off smoothly so that there isn’t any bumps.

Also To make sure that the motors go at the same time, I would drive the motors all the way to the home point then release the motors by pressing the red button (or Emergency Stop in software) this should release the power from them so that can freely move and then make sure they are both at the end stops hard. Then reapply the power by pressing the yellow button or the unlock button in the software. Then do a find X home command and then a set X home command. Lastly I would then either measure the X axis and put in that valve or find Length X command. All of this can be found in the setup option under Axes

Cheers
Jeremy

[voortwis]

I really hope that the firmware will be upgraded/fixed to use the encoder(single) to try to adjust the motor rotation(steps). Then, also do this for the second x motor. Right now, when one motor is skipping steps the gantry will get skewed increasing friction and ending in an endstopped state.
I tried to figure out how to fix the firmware but this is definitely not my cup of tea.
Another solution would be (but sadly we have the steppers soldered to the farmduino) to use closed loop motor drivers ( Mks Servo42d ). These can also be controlled using a CAN bus (RS485). When controlling all motors like this we would only need 2 powerlines and the canbus which all can be shared with all motors.