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Arduino, GRBL, Nema23 - SOLVED

Discussion in 'Controller Boards' started by Jason Harding, Sep 12, 2017.

  1. Jason Harding

    Jason Harding Well-Known
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    I am pretty sure as a couple of you veterans read the title a couple of you rolled your eyes. I have a feeling I already know what the answer is going to be but I am going to ask the question anyway.

    Just finished putting together my CNC machine and finished wiring it tonight. While doing some pre-testing the Arduino+GRBL+nema23+24Volt, 15 Amp PS, worked OK. Now I am noticing that with the lead screws and all connected i am getting what I can best describe as a "stall" in the motors when under load. (loud noise and no movement), there is no binding in the axis anywhere.

    Has anyone had success with my combination working without issue?
    Would upgrading to a 36 Volt power supply help the issue?

    I am suspecting that the GRBL shield is the issue, its not able to provide enough current to power the nema23s. I am also suspecting that although specs state it should be able to operate a nema 23 it was more designed to operate a nema 17 or 14.

    2nd part to the question is as follows. Would you recommend changing to TB6600 or other external stepper drivers? Could anyone suggest a good stepper driver I can use?
    Budget is a concern as to why I originally attempted to use the GRBL.

    Suggestions please.
    thanks in advance
    Jason
     
  2. David the swarfer

    David the swarfer OpenBuilds Team
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    this is usually a sign that the acceleration and/or speed is too high for the power settings.
    the GRBL shield will run the NEMA23's just fine but at only about 1.5amps. that is about half power <-: which means top speed will be restricted.
    Mark used almost exactly that in the initial build video, xPro board I think, which cannot do the full 2.8 amps the motors are rated for.
    yes.

    power(watts) = volts * amps
    since the max amps of the driver/motor is limited, the only way to increase power is to increase voltage. BUT, the drivers have a max voltage rating, so be careful.
    Yes, either TB6600's or DQ542 drivers on 24+ volts is very good. My DQ542's arrived last week ..... (-:
    Keep the GRBL shield for your ACRO laser build (-:
     
  3. Jason Harding

    Jason Harding Well-Known
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    Hi david

    Thanks for the reply, going to get the end stop switches mounted up and then continue testing. Do u know if there is a good setup guide for the grbl?
     
  4. David the swarfer

    David the swarfer OpenBuilds Team
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    there is, the GRBL Wiki at Home · gnea/grbl Wiki · GitHub

    do get the machine working correctly without limit switches before enabling homing.
     
  5. Jason Harding

    Jason Harding Well-Known
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    I was thinking about setting them up to prevent the machine from overrunning the leadscrews. Didn't think about homing and the end stops going hand in hand.

    I will take your advice and work with the motor control issues first
     
  6. Jason Harding

    Jason Harding Well-Known
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    HI David,

    Thank you very much, I got the machine up and running, It was a simple solution of bringing down the steps. Im running 1/4 step right now with 640 Steps per inch in the GRBL config. everything is running well. Haven't done any long time runs yet to see how heat affects but printing up an enclosure with a fan mount so hopefully that wont be an issue.
     
  7. Gary Caruso

    Gary Caruso Veteran
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    I had a Grbl shield on the x-carve, worked fine even using two Y steppers on one channel, the real "grbl shield does something like 2.5A per channel. but is limited to 30Vdc.

    Edit: sorry i'm thinking of the GShield!

    Cooling fan is a must for sure, What steppers are you using? what lead screw? i'm trying to picture how a lead screw comes out to 640 SPI? at 1/4 micro steps you have 800 steps per rev.
     

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