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OX - Shaky/Weak X and Y axis.

Discussion in 'CNC Mills/Routers' started by Brayden DeVito, Nov 26, 2014.

  1. Brayden DeVito

    Brayden DeVito Well-Known
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    Hey guys,

    thanks for all of your help on this!

    I have a Protoneer CNC GRBL Arduino shield.
    It is being driven by 4 StepStick A4988.
    24V 30A Power Supply.

    I understand the NEMA 23's are being under powered due to the drivers not being able to output enough current to each stepper motor.

    This should just affect the max torque, right? When i'm moving in the x or y axis, it seems extremely shaky and weak.... any ideas?

    Do I need to adjust the potentiometers on the stepper motor drivers to optimize the 23's? I'm having some issues with this and can't seem to figure it out. Before i start twisting the potentiometers, I had to see what you guys/gals say in here.

    Thank you so much!

    Brayden
     
  2. Joe Santarsiero

    Joe Santarsiero OB addict
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    You figure this out yet? Generally you'll need to fine tune those pots. Off the top of my head also pay attention to your step resolutions and feed rates. What steppers are you using?

    Good luck
     
  3. Brayden DeVito

    Brayden DeVito Well-Known
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    Joe, I didn't quite figure it out..

    Im using the motors on the open builds part store.

    I moved the pots on the board until the machine was moving smoothly.. This probably isn't the most accurate way to go about it...

    Step resolution is that a part of the GRBL settings? I noticed the 17 responds much better to feed rate changes, the 23s not so much.... I'm getting close!

    The settings are not quite there either... When I tell it to move 1 inch, it goes about 3/4 of an inch.. So I'm working on that as well.

    Any input is appreciated. Thanks!
     
  4. Joe Santarsiero

    Joe Santarsiero OB addict
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    You need to get into your GRBL settings. Have you played with that yet? You should go in and make sure all of your step pulse settings are correct. You shouldn't have a problem driving those 23's with that set-up.
    Also, note that there should be some jumpers on the board that are dedicated to adjusting the step amount. Your drivers are capable of 1/16 microsteps. You may have to get into GRBL and make sure all of your numbers add up (if you haven't aready!). Also, make sure you are in the correct in/mm mode (sounds like you are. It really only sounds like your 23's are receiving too many pulses and missing some, but I could be wrong on that.

    If you can grab your GRBL settings and post em I'll give you a second set of eyes on them. Make sure you're firmware is all up to par too.

    Maybe some other arduino based builders around here will help out too!

    I use a TinyG so I'm almost in the same boat, but not quite.

    Also, what software are you using to interface?
     
    #4 Joe Santarsiero, Dec 8, 2014
    Last edited: Dec 8, 2014
  5. Brayden DeVito

    Brayden DeVito Well-Known
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    Joe,
    You rock!

    I'm running GRBL 0.9G
    GRBL Controller 3.6.1

    See attached photo of the GRBL settings..
    I can't seem to find jumpers for step size....

    GRBLSettings.png
     
  6. Joe Santarsiero

    Joe Santarsiero OB addict
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    Try setting $0 = to between 10 and 15
    And $1 = 50
    Then give it some x and y commands. You may have to turn those drivers up. Start at 12 o'clock and work your way up.


    I'll have to look through the rest of your settings and the board and driver schematics later after work.
     
  7. Joe Santarsiero

    Joe Santarsiero OB addict
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    What size pulleys are you using?
     

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