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Two stepper motors one driver problem

Discussion in 'General Electronics' started by ealvizouri, Nov 7, 2019.

  1. ealvizouri

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    Hey guys, let me start saying that I'm a total newbie in electronics and CNC machines. I'm building a CNC laser cutter. I'm using Chinese components:
    • Cloudray Ruida RDC6442S controller
    • Leadshine microstep driver DM542
    • Switch Power Supply LRS-75-24 (24V)
    • RDWorks V8

    As well as OpenBuilds parts:
    • Stepper motors NEMA 17
    • Micro limit switches

    I'm practically building the CNC based on youtube videos, specially this one, where he explains the electronics.



    I have two drivers DM542 one for axis X and the other one for axis Y, which I intend to have two stepper motors connected in opposite direction. So I tried the exact same connection that he does in the video (switching letter with the same sign):
    • A + |--------| B +
    • A - |--------| B -
    • B + |--------| A +
    • B - |--------| A -
    Note: I also tried switching signs instead of letters.

    I tried different PA settings, the last one that has worked better than the others is:
    • SW1 off SW2 off SW3 on (2.37A)
    • SW4 (half current)
    • SW5 off SW6 off SW7 on SW8 on (1600 pulse/rev)
    But still, it doesn't work as expected. You can watch the videos with different views, where you can see how at some point the left side motor starts to vibrate and the right side motor moves smoothly.




    Here are some photos where you can see how I wired the drivers and motors.

    IMG_20191106_220620465.jpg

    IMG_20191106_220751363.jpg

    I have tried multiple settings and always there is the motor that doesn't work as expected, I even switched the motors just to make sure they worked. I don't know what else I can do, I'm thinking it's a problem of calculations that I don't know of...but I'm hoping it's something simple but for my lack of experience and knowledge I'm not able to determine what's the problem, I hope one of you guys can give me an idea of what's happening and what else I could try.
     

    Attached Files:

  2. Rick 2.0

    Rick 2.0 OpenBuilds Team
    Staff Member Moderator Resident Builder Builder

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    Only switch one pair on the second stepper when you want opposing motors.
    A+ A-
    A- A+
    B+ B+
    B- B-
     
    Peter Van Der Walt likes this.
  3. jeffmorris

    jeffmorris Well-Known
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    I thought that you're not supposed to run two motors off one driver.
     
  4. Alex Chambers

    Alex Chambers Master
    Moderator Builder

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    Not necessarily a problem - wired in series they will get all of the current and half of the voltage each. In parallel all of the voltage and half the current.
    Alex.
     
    sharmstr likes this.
  5. ealvizouri

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    Thanks for your answer. I tried it and didn't work either, here's the proof
    IMG_20191107_123818088.jpg

    Here's the video
    https://photos.app.goo.gl/1BrURRKdTm4K9Mcm7


    I don't know, but this guy pulled it off



    Thanks for your answer, to be honest with you I don't know which one is. In order to have both motors working properly which one should I choose?

    I appreciate you all for your feedback.
     
  6. Giarc

    Giarc Master
    Moderator Builder

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    I thought it is a bad idea to run the y axis with two separate motors in case one craps out. If that happens and the mirrors get out of alignment bad things (like fires) can happen. I though one motor usually drives a shaft that has two pulleys to always keep both sides in sinc. Maybe I am wrong, but that is how I have seen it on CO2 lasers.
     
    Peter Van Der Walt likes this.
  7. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
    Staff Member Moderator Resident Builder Project Maker Builder

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    That is 100% the best advice for any laser design. I've seen the consequences of disobeying that design rule first hand!
     

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