SOLVED Understepping z-axis

Discussion in 'Build Help' started by hexler, Jun 14, 2016.

  1. hexler

    hexler Member

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    Sorry if this is something simple, first time dabbling in 3d printing, and I have been learning a ton throughout the build. the build is complete, everything seems to be functioning as intended. The issue I've come across is the Z axis, when I go to manually move it, does not move as far as it thinks it is. to help clarify what I mean. say i turn the bigbox on with the z all the way down, and manually try to move it up, it will slowly move upward, but it stops when the display shows 300mm, but in all actuality, it has only moved less than halfway up, maybe 140 or so mm. I have to turn it off, and back on, then repeat until I can move it up all the way or down all the way. I used the 1.8 degree motors, the z axis steppers are set to .569 volts. am I missing something here? would adjusting the z pot to .6-.65 help at all since they are tied together on the board output? I'm just not sure what kind of issue I'm having at this point, any help would be appreciated!
     
  2. Sarah Nicholson

    Sarah Nicholson Well-Known Member

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    Are you homing first? If you don't home, the printer has no idea where the bed actually is and you won't be able to move it freely.
     
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  3. hexler

    hexler Member

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    It was during the first homing I actually discovered this issue. The bed was completely lowered to start. the y hit its end stop, the x hit its end stop, the carriage moved to the middle of the build plate, then the z started to raise, and stopped below half way. I turned it off and on, tried the homing again, and it did the same thing, but the bed went up another chunk, the third time, it finally got to the sensor and appeared normal, but I knew there had to be an issue with the Z. upon manually(per the 1mm menu option) trying to lower it, found that it thinks it is moving 300mm, it just isn't moving 300mm.
     
  4. Chase.Wichert

    Chase.Wichert Well-Known Member

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    are you sure you used the 1.8 degree ?
     
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  5. Chase.Wichert

    Chase.Wichert Well-Known Member

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    if you used the .9 this would be the outcome
     
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  6. hexler

    hexler Member

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    I will triple check when I get off work, and I surely hope it didn't miss this twice, because that was my first thought as well. But I'm certainly capable of such a mistake, i'll update after I check it out again.
     
  7. Chase.Wichert

    Chase.Wichert Well-Known Member

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    lol arent we all
     
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  8. hexler

    hexler Member

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    1.8 Confirmed. I just checked both, indeed both are 1.8 degree motors, both are functioning, triple checked wiring as well, it is correct. I took a video (which i can't upload here) after auto homing the bigbox. out of curiosity, I got the calipers out and found that per 100 mm it think it moves, it actually travels 25mm. i tried tuning the z pot higher and lower, with no benefit at all. any ideas what else could be causing this issue?
     
  9. Stian Indal Haugseth

    Stian Indal Haugseth Well-Known Member

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    How are the jumpers under the stepper driver? And what firmware are you using?

    Adjusting voltage would not change steps.
     
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  10. Chase.Wichert

    Chase.Wichert Well-Known Member

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    Look in the LCD Menu for your Z steps/mm, control, motion, then z steps.
     
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  11. hexler

    hexler Member

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    chase, it shows 400 steps/mm.

    stain, 1.1.0-rc4 is what comes up upon boot. i don't know exactly what jumpers i'm looking for, if it is on the bottom of the board it could be tough to check without pulling it out. is there a specific solder joint or cable i need to look for?
     
  12. Chase.Wichert

    Chase.Wichert Well-Known Member

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    There are jumpers under the motor drivers. You would need to remove the z axis motor driver, and look at the jumper settings.
     
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  13. Chase.Wichert

    Chase.Wichert Well-Known Member

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    Some versions of the Rumba contain dip switches located underneath the driver boards, but current versions may contain a row of 3 jumpers.

    with DRV8825
    1 2 3 step mode
    0 0 0 Full step (2-phase excitation) with 71% current
    1 0 0 1/2 step (1-2 phase excitation)
    0 1 0 1/4 step (W1-2 phase excitation)
    1 1 0 8 microsteps / step
    0 0 1 16 microsteps / step
    1 0 1 32 microsteps / step
    0 1 1 32 microsteps / step
    1 1 1 32 microsteps / step
     
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  14. Chase.Wichert

    Chase.Wichert Well-Known Member

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    My Z-steps show 1600.. so that would be your problem. Where did you get the firmware from?
     
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  15. hexler

    hexler Member

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    it was the pre-loaded firmware that came with it!
     
  16. Chase.Wichert

    Chase.Wichert Well-Known Member

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    Ahh yeah you will want to put a new firmware on...
     
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  17. Chase.Wichert

    Chase.Wichert Well-Known Member

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  18. hexler

    hexler Member

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    howdy chase, finally getting around to working on it again. I downloaded the xloader, and the .hex file (from https://github.com/BigBox3D/Firmware).
    I opened the xloader, selected the hybrid dual .hex file, it only shows COM1 (usb port is connected to usb mini on rumba), i selected the Mega(ATMEGA2566) device and clicked upload. just says can't open port. any suggestions? never had to manually load in firmware before, just assumed i'd get a board that's functional upon setup lol. also, the other guide said have it powered on, so i'm assuming this is the same? Thanks again for the help!
     
  19. Alex9779

    Alex9779 Moderator
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    Did you install the drivers for the RUMBA?
     
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  20. hexler

    hexler Member

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    sigh. i did not.....thanks alex, chase for the help. benchy is officially under way
     
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