Closed loop calibration on a dual axis setup?
-
Last night, I got my steppers (with internal 4,000 PPR quadrature absolute/incremental encoders) wired and operational under closed-loop mode with my 1HCL boards. Huzzah!
I did so with the axes on my gantry disconnected, however. It's an XY cartesian system with dual Y rails, each powered by a stepper. The steppers for Y thus turn in opposite directions.
My question: how can I perform the calibration move without dismantling the axes, short of stressing them? They are belt-driven actuators, so 5 full steps moves one Y actuator noticeably in relation to the other, which I'd like to avoid.
-
@usinjin running the calibration for multiple motors at the same time is on the feature request list:
https://github.com/Duet3D/RepRapFirmware/issues/758
Best regards
-
@T3P3Tony Oh, I missed this--thanks!
-
@usinjin you could maybe just loosen the pulley on the motor shaft? then the motors turn freely, but in-place on the machine.
-
@oliof Yes, this works well, but I was hoping for something a little more automated, as they're not that easy to get to.
I also realized the bigger problem is that it outright fails calibration on the dual axis. The backlash recorded on each side is always just over the threshold. I really want to find a way to calibrate easier and run closed loop. Or just not have to calibrate at all. Is there no way to store the recorded backlash value from running M569.6 Pnn V1?
-
Follow-up, this is basically what I ended up doing. I realize this may not be a good idea in practice, but it does seem to work. I rebuilt the firmware so that in the event of excessive backlash, a warning is issued, and a static value is assigned. Each 1HCL has it's own value it sets.
