One of my steppers is much weaker

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This topic contains 8 replies, has 5 voices, and was last updated by  Erwin Vigilia 1 month, 2 weeks ago.

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  • #105050

    Jay
    Participant

    I noticed that one of my motors on the X axis is much weaker than the other three. What could be causing this problem? It moves but it’s far less powerful than it should, this also makes it quite easy to be rotatated when it should be holding the position.

    #105068

    Ryan
    Keymaster

    How is it wired, what drivers, what board, what firmware, what stepper? The question is just to general to help.

    #105074

    Jay
    Participant

    I’m using the lcd dual endstop firmware, and the hardware suggested for the arduino/ramps build, I’m using cheaper clones for the arduino and the ramps, and the same drivers shown in your build instruction, plus generic chinese nema 17 motors off banggood.

    I wired it to its own driver as I’m using the dual endstop firmware.

    Ramps: https://www.amazon.it/gp/product/B07BSRS9WS/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

    Mega: https://www.amazon.it/gp/product/B071W7WP35/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

    Stepper Drivers: https://www.amazon.it/gp/product/B07K9ZB7M5/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

    Motors: https://www.banggood.com/Nema17-59Ncm-2A-1_84-lead-48mm-Stepper-Motor-For-3D-Printer-CNC-p-1252415.html

    #105079

    Barry
    Participant

    Check the stepper voltages.  One could be lower than the other.

    #105085

    Erwin Vigilia
    Participant

    Check the stepper voltages. One could be lower than the other.

    That and one of my favorite questions: what did you adjust the stepper reference voltages to?

    2 users thanked author for this post.
    #106282

    JeffH
    Participant

    I have encountered the same problem with my Lowrider Z axis and adjusted my Acceleration distance and Start feedrate in Estlcam to compensate. On my new Lowrider I am using an Arduino Uno, CNC Shield, with the 8825 drivers  – reference voltage adjusted to 0.8V for my Nema 17 motors 1.7A 84 oz.in. One Z motor started acting up when the Estlcam settings were set to default (long story, two computers) with Acceleration and Start feedrate at 2 and 2 and Max accel to 50mm/sec. Changing them to 2 and 8 and slowing the Max feedrate to 40 seemed to solve the problem. I had also noticed that moving the Z steppers very slowly prevented the ‘weak’ Z motor from acting up.

    I have the two steppers on the Z axis wired in series as recommended but the consequence of that as I understand it is a voltage reduction:

    “The same current flows through each part of a series circuit. The total resistance of a series circuit is equal to the sum of individual resistances. Voltage applied to a series circuit is equal to the sum of the individual voltage drops.”

    In other words the amps stay the same in a series wiring but the voltage is divided between the motors. I will also be trying a 24 volt power supply and see what results I get with that. It should solve the problem.

    My final step will be to wire the steppers individually to TB6600 drivers (which I was going to do anyways, long story, 4 axes, Arduino Mega) and each motor will get a full 12 volts.

    Being no expert, I may be off base with my electrical theory and if so hopefully someone will correct me.

    #106319

    Erwin Vigilia
    Participant

    The OP hasn’t chimed in for bit, so maybe he solved his problem…

    Being no expert, I may be off base with my electrical theory and if so hopefully someone will correct me.

    Nothing wrong with your theory (Kirchoff and Thevenin would be proud). What matters here, in terms of voltage, is your motor coil rating and your stepper driver specified min Vcc. For the TB6600 and 8825, that is 8.0V and 8.2V respectively. I don’t know which motor you’re using, but the OP’s motors are rated for 2.8V (at 2A) per phase. 8825’s which are rated for 2.5A max, really less, the way these particular modules are built… barely adequate heat sinking. Forced air helps. The TB6600 is rated for 4.5A peak. Bottom line, 24V should work for his application.

    1 user thanked author for this post.
    #107860

    Jay
    Participant

    Ok the solution was pretty easy and will make me look like a noob but just to help somebody else who may have a similar problem here is what i did: I swapped 2 motors, the “weak motor” started working fine in its new location, and another good motor begun working not fine in the weak motor’s place. So it was not the motor, I checked the continuity of the connection with a multimeter, found a faulty cable (most likely some bad soldering job for the extension), I changed it and everything works fine now.

    1 user thanked author for this post.
    #107867

    Erwin Vigilia
    Participant

    Ok the solution was pretty easy

    Best kind! Glad you solved the problem, it’s funny how often the fix is the simplest despite how much “science” is thrown at it (I’m looking in the mirrow when I say that, lol).

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