First time Z-axis calibration, Bed wont go down

Discussion in 'Calibration, Help, and Troubleshooting' started by Boerta, Oct 5, 2016.

  1. Boerta

    Boerta Member

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    So, I've finally gotten to step 6 in the printer commisioning chapter of the manual.
    I've loosened the z-axis motor, and I'm trying to lower the bed all the way using the motion controls (1mm, z axis, under the preparation menu).
    The firmware lets me turn the knob until the screen says 300mm (i forget if it's plus or minus), but won't let me lower the bed any further.
    At this point, the bed is only about halfway down to the bottom.. What gives?
    I have the new lead screws with the increased lead, and I've turned z-steps/mm down to 400, as per the manual.

    Any clues?
     
  2. Ephemeris

    Ephemeris Well-Known Member

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    Sounds like your steps/mm are off by two. Verify this by carefully measuring how far it moves when you command it to go down some distance that you have the tools handy to measure accurately. If it's exactly a factor of two, you know what to do. Why is another matter, but life is short and it won't matter so long as you set it up to move correctly.
     
  3. Boerta

    Boerta Member

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    I measured, and sure enough, when the firmware moved 1 cm, the bed had really moved 5 mm. I set the zsteps to 800 and it seems fine now.
    This makes me wonder though.. Is the build manual just wrong, and the big box guys haven't really built a box with the new lead screw? Is there a third type of lead screw going around?
     
  4. PsyVision

    PsyVision Moderator
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    I have the 8/8 leadscrews and have the steps of 400. I wonder whether you have used the correct motors. Using 0.9 step compared with the 1.8 step would create a double / half problem that you are seeing.
     
  5. Boerta

    Boerta Member

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    Ah, that makes sense!

    I don't really feel like taking the bottom off to check at this point, but I'm fairly sure I only got two types of motors - 4 motors at 0.9 step and 2 pancakes for the extruders. My X and Y motors are both 0,9 step ones, at any rate, and the X and Y dimensions seem correct, but I haven't checked that thoroughly. At least the autohome finds the middle of the build plate.

    Are the Z axis motors supposed to be 1.8?
     
  6. C.C.M.

    C.C.M. Member

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    I have seen this posted a few times. The first time I saw it I checked all my motors and they are all 0.9 step, was there a version that had 1.8 step?
     

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