Two Y Steppers....followup Q's.



  • Now that I actually have a Duet WiFi wired up and playing with it...Duet is pretty amazing ...I have some specific questions please. Sorry for being so anal, but my first printer and very little Duet/Gcode experience.
    Previous:
    @https://forum.duet3d.com/topic/9962/confirmation-of-y-stepper-wiring-please/18

    I'm considering only two options now for the Y axis two motor control.

    1. Using two drives, 1(Y) and 4(E1), separately on the motors, each with it's own endstop.
    2. Using the Z drive series input...one, maybe two endstops?

    Would like to go with option 1.
    Key questions: By jogging Y, the printer can repeatably trigger mswitch endstops to 0.1mm, good enough (I think) for homing and two motor axis alignment. But what happens if, during a print, one stepper starts getting out of alignment due to friction, step drift in motors or whatever? Can/do the drivers crosstalk somehow on missed steps, or in some way maintain alignment of the two Y steppers?
    Can the printer be coded to shut down if it senses Y axis skew before damage occurs?

    Option 2 - second choice.
    Q's: If I map the two Y's to drive 2 (Z, series ports), are there any cascading effects, e.g. is the Z-probe input affected (I want to use Mode 5)? To get more V per motor, how wise is it to bump the current up, eg two 1.5A steppers in series run at maybe 1.4A?
    In series on one driver, can you still get missed steps/misalignment of the steppers? More or less likely than with separate drivers?
    Thank you.



  • @danl I can give you some insight on option 1... There's no explicit synchronization between the drives but I use 2 steppers for X and 2 for Y and have never had the steppers get out of sync as long as power stays applied and as long as the motors get enough current to not skip on their own. Both of those statements apply even if the motors are driven from the same driver so you should be OK.



  • @danl said in Two Y Steppers....followup Q's.:

    one stepper starts getting out of alignment due to friction, step drift in motors or whatever?

    then you get layer shifts like with one y motor. if that happens during printing you need to fix the mechanical problems or reduce jerk/acceleration. there are closed loop stepper motors that can sense and correct that but that should normally not be required.

    q2) not that i am aware of.
    you should run the steppers at about 75% of their max current or cool them very well.

    if you are really worried about the 2 y getting out of sync than get a Endless belt and connect the 2 y axis to one motor. then they should not get out of sync.


 

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