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Motor Synchronization

Discussion in 'Motors' started by ricklach, Sep 3, 2019.

  1. ricklach

    ricklach Well-Known
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    The motors on the belt-driven axis of my machine seem to be out of synchronization and there is a noticeable twist when jogging forward or backward. Is there an easy way to synchronize the motors to eliminate this twist?
     
  2. Rick 2.0

    Rick 2.0 OpenBuilds Team
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    If everything is plugged in properly there is no possibility (other than a bad driver) of motors being out of synch. Start by checking all the wiring, looking for loose connections. Make sure both Y motors are plugged into the Y ports on the BlackBox. Make sure the jumper on the BlackBox is set to match the Y motors. Make sure the amperage trimmers on the side of the BlackBox are set to the same setting for both the Y motors. Make sure the steppers are a matched pair (same size, same step angle). If the problem is not electrical check the physical system for binding. You don't note what kind of propulsion your system uses but if it is screws make sure the screws are not binding. Make sure the wheels move freely.

    Give all this a check and report back...
     
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  3. Gary Caruso

    Gary Caruso OpenBuilds Team
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    Ricklash, For belt drive make sure one motor is reversed! just swap any one motor poles wire around.
    Cheers
    Gary
     
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  4. sharmstr

    sharmstr Master
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    What Gary said, but one thing not mentioned, which was why my belt drive got out of whack was a loose pulley on the motor shaft. One of the grub screws had backed out.
     
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  5. ricklach

    ricklach Well-Known
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    I think I understand about swapping the wires around, but to be sure can you be more specific.
     
  6. sharmstr

    sharmstr Master
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  7. ricklach

    ricklach Well-Known
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    OK, I tried swapping the wires at the motor and that did not solve the twisting of the gantry when reversing direction on the y-axis. Checked the grub screws and they are tight. When I ran the homing app there is a lot of vibration when moving on the y-axis. Any other suggestions?
     
    #7 ricklach, Sep 4, 2019
    Last edited: Sep 4, 2019
  8. sharmstr

    sharmstr Master
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    Did you actually verify that one motor wasnt moving the right way? Or did you just switch the wires hoping that would fix it? This is important because you could have just compounded your problem. When jogging, the motor shafts should rotate in opposite directions (one clockwise the other counter-clockwise)

    Grub screws can be tight, but if not on the flat of the motor shaft, the pulley can still be loose.

    With the motors off, do both sides of the gantry move smoothly? Or does one side lag due to overtight wheels as Rick suggested?
     
  9. ricklach

    ricklach Well-Known
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  10. ricklach

    ricklach Well-Known
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    Returned the wiring to original positions. Checked the direction of travel of both motors - OK. grub screws tight and on flats of shaft. Gantry moves smoothly with motors off. Did some more testing and it seems that when set on 1mm increments the left motor (looking from the front or router side of the x-axis) moves 1mm before the other motor kicks in. In fact, what is happening with the right motor is that it moves 1 mm in the opposite direction of travel before it reverses and moves in the correct direction.
     
    #10 ricklach, Sep 4, 2019
    Last edited: Sep 4, 2019
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  11. sharmstr

    sharmstr Master
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    Cool. Moving on.....

    Is your gantry square in a resting state? I had an issue with the gantry no being square early on: OpenBuilds WorkBee 1510

    Are both Y belts under correct tension?

    Any strange noise coming from the one the motors? Like it cutting out or a short?

    It might be helpful to know what control board you have. A video of the issue might help us ID the problem as well.
     
  12. ricklach

    ricklach Well-Known
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    I have the blackbox controller. No strange motor sounds. I believe both belts are tensioned properly. Gantry is square. Movement along the x-axis sounds sweet, just like I would expect. Movement on the y-axis is harsh, noisy, with lots of vibration. I swapped the master slave configuration, then changed it back becaus everything was moving in opposite directions. Changed the wiring on the y-slave motor and that seems to have solved the problem. No more gantry twist, both motors move in the correct direction on forward and reverse, sounds like the x-axis movement, no more vibration. I think, with your assistance and ideas that we have solved the problem. If there is any change I will open a new thread
     
    #12 ricklach, Sep 4, 2019
    Last edited: Sep 4, 2019
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  13. sharmstr

    sharmstr Master
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    That sounds like a wiring issue. I had that once and one of the motor wires became loose on the black box and was shorting out. It looked like they were okay until I really looked at them and pulled on each wire. Then it was obvious. I could actually see it shorting when I was jogging. Sounded terrible.

    The other thing it could be is that you dont have your motor wire pairs correctly identified. So instead of having A+ A- and B+ B-, you have A+B+ and A-B- or some wrong combination like that. Although the build videos are awesome, there's an assumption that your motor wire colors are the same as in the video. The best thing to do is ID them yourself. Here's a good write up on how to do that: C-Beam Machine XLarge
     
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  14. Gary Caruso

    Gary Caruso OpenBuilds Team
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    Please post your grbl settings, also make sure the current is set the same on both Y motor channels, half way on both trim pots should get you going.
    Cheers
    Gary
     
  15. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Sounds that way when 3 of the 4 wires only make contact. Recheck all joints, terminals, connections you made
     
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