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Unresolved Z axis off by 1/5th

Discussion in 'Troubleshooting' started by Senator1891, Mar 29, 2016.

  1. Senator1891

    Senator1891 Member

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    Hello all,

    I put down the printer because it was driving me crazy. I finally got it printing, but now the z-axis is printing items short. Just printed a cube that should be 50mm high, but it came out 40mm high. The width and length are both correct. I am using mattercontrol to alter settings, and cura to print. I have already swapped out the z-axis stepper motors. I have uploaded the 8mm lead screw firmware.

    PLA
    190 degree hot end
    60 degree bed temp
    Initial Layer .3mm
    Initial Layer Line Width 100
    Travel Speed 150.0 mm/s
    Bottom/top thickness 3mm
    Diameter 1.75
    Flow 100%
    Nozzle Size 0.4mm
     

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    #1 Senator1891, Mar 29, 2016
  2. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    What printer (exactly: Beta, R1, R1+, any upgrades -- like leadscrew replacement)?

    What are your Z steps/MM?
     
    #2 mark tomlinson, Mar 29, 2016
  3. Senator1891

    Senator1891 Member

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    I believe mine is the Robo R1, not the +. I have gotten the most accurate results from the mm firmware. I believe it is the 8mm lead screw.

    It is currently set to 2560, I have tried decreasing by 5 and increasing by 5 with varied results. The main thing I am hoping to learn is if decreasing steps/mm should theoretically increase or decrease the height. My assumption is that if something requires more steps within a mm it may make the object taller. This is assuming that the step is a standardized unit of measure used to tell the printer how tall an actual mm is.
     
    #3 Senator1891, Mar 29, 2016
  4. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    With 5/16" threaded rods your steps per unit should be

    #define DEFAULT_AXIS_STEPS_PER_UNIT {80,80,2267.72,723.38}

    For 8mm threaded rods the steps per unit should be

    #define DEFAULT_AXIS_STEPS_PER_UNIT {80,80,2560,723.38}

    for leadscrew update (which includes the R1+) the steps should be:

    #define DEFAULT_AXIS_STEPS_PER_UNIT {80,80,800,723.38}

    Measure the threads/inch on the rods.

    18 threads per inch for 5/16"-18 rods
    ~20 is M8

    I do not know off the top of my head what the leadscrews are, but if you do not have the couplers -- you have leadscrews :)
     
    #4 mark tomlinson, Mar 29, 2016
  5. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    The steps are standardized for the steppers.
    NEMA 17 is normally a 1.8deg step angle (200 steps/rev)
     
    #5 mark tomlinson, Mar 29, 2016
  6. WheresWaldo

    WheresWaldo Volunteer ( ͠° ͟ʖ ͡°)
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    A few things to try, in no particular order and no guarantees of success.
    • Increase the tension on the Wade's extruder Idler arm, it will push the filament a bit harder into the hobbed bolt and may help get more consistent flow.
    • Calibrate the eSteps for the extruder, if you ask for 100 mm of filament, make sure it gives you 100 mm not 80 or 120.
    • Reduce the extrusion multiplier, It does appear to be over extruding ever so slightly.
     
    #6 WheresWaldo, Mar 29, 2016
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  7. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    I still think given the size of the error that there is something misset in the firmware. The numbers are mechanical and I can't see the mechanical parts being that far off (40mm vs. 50mm). Still, those are all good things to check I just don't think that would account for an error that large. (If it needed 2560 and had 2267.72... however... that would make it short by roughly 10-15%)
     
    #7 mark tomlinson, Mar 29, 2016

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