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Workbee movement problem

Discussion in 'CNC Mills/Routers' started by Wallied, Nov 26, 2019.

  1. Wallied

    Wallied New
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    Hey. Since I rebuilt my Workbee about a week ago, I've been having a peculiar problem, and now am hoping someone has faced a similar problem before and could help me cut down on the time spent troubleshooting.

    Put shortly, the machine doesn't move to Y+ X+ and Y+ X-. All axes move like they should individually, and with each other, except for this one direction. Even Y- X- and Y- X+ work, just not this one direction.

    When I jog on UGS to Y+ with a simultaneous X move to either direction, the X moves seemingly as it should, though accompanied by some rattling sound which I'm not encountering on any other moves. The Y motors don't move at all when doing this particular direction. Tried loosening the couplers, and the motors are not turning at all nor making any sound, but do a move in any other direction and Voila!, they turn exactly like they should. While this is happening (or not happening, if you will), GRBL tells me the axis is moving.

    Originally I blamed my motor wiring, thinking it was the fact I used unshielded cables, but after changing them to shielded ones, I can say with confidence it isn't that.
    A faulty driver would be a popular guess if the problem were "broader" (one direction only or not working at all). But since the machine otherwise moves like before, with more than enough torque (the most I've dared to try was 20.000 mm/min, and even then I couldn't stall the gantry by pushing).

    Next things I'm going to try are to redo the Arduino-to-driver wiring (twisted pairs, worked without a hitch before), powering the Arduino through a wall wart instead of USB and reinstalling both GRBL and UGS. After that, only a faulty Arduino comes to my mind as a possible reason for this.

    And since it's relevant, here's what I'm running:

    -Workbee 750 x 1000, leadscrew driven axes, with X-axis being reinforced
    -Arduino UNO with screw shield V3 for easier wiring
    -Four DM860A Stepper drivers, all supplying 2 Amps RMS current at 50 Volts (if I remember correctly, might be 55V or 60V too)
    -Four 3A stepper motors (272 Oz-in ones if I remember correctly), microstepping at 1/4 step
    -One limit switch per axis, wired NC, pull up resistors and capacitors implemented as per recommended
    (-VFD is the common HY one, running a 1,5kW water cooled spindle) The VFD can't be the culprit as it currently is not installed.

    Regards, Will

    Edit:
    After redoing the wiring between the screw shield and the stepper drivers the problem jumped to X+Y- and X wouldn't home anymore. After removing the screw shield and reattaching it to the Uno, I've lost Z entirely and homing doesn't make anything move anymore.

    So, now I'm pretty certain it's either the shield or the Arduino. Went through the board with compressed air and circuit cleaner and when it's had time to dry, I'll try again with my older screw shield (the new one looked fine, so I doubt it's the culprit) and if the problems persist, I'll get a new Uno. After that it would be dismantling the controller box :banghead:
     
    #1 Wallied, Nov 26, 2019
    Last edited: Nov 28, 2019
  2. Wallied

    Wallied New
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    Now, after replacing, dismantling, checking and measuring pretty much all the electrical components on the machine, and eventually the problem turned out to be the signal wires' connector on the Arduino Uno. After successfully trying a second card I tested wiggling the connections and was able to deduce the connection problem.

    So, If you face similar illogical movement issues on your machine, check the connectors before you redo a couple dozen solder joints and such just to make sure you did them correctly the first time around ;)
     

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