Z-Axis positioning inconsistent

Discussion in 'Calibration, Help, and Troubleshooting' started by pSimon, Sep 28, 2016.

  1. pSimon

    pSimon Member

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    Just trying to finalise the commissioning of my BB (dual hybrid1.1.0-RC6)


    Having done the setup, I had a Z offset of -0.7, however on trying an auto-level, the head moved right front, then mashed into the bed as the bed was raised.

    Not good. :(

    A while later, I tried running the bed up manually (and slowly!) in the same position. Even though the sensor was over the bed, it did not seem to trigger. I tried reducing/altering the lighting, but that didn't have any effect.

    I have a Clever3D bed, so I tried fitting that.

    Z offset is now ~2.5mm [very different!], and an Auto-Level now does not crash.

    BUT some measurements of the nozzle/bed gap suggest that the Z homing isn't consistent, in that it can be anywhere between 2.0 -2.5 mm.

    This feels a bit like the Z sensor is misbehaving. One thing I have noticed is that the red light on the sensor flashes/flickers rapidly when the z has homed - is this normal?
     
  2. pSimon

    pSimon Member

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    Flashing is due to the sensor being blinded, so the plain silver Clever3D beds simply don't work with IR. They really shouldn't be selling them without some kind of warning.

    Reverted to plain glass bed, but the sensor is back to its old behaviour - at front right, it doesn't trigger at all (unless you stick something like paper in).

    Not impressed by this Z sensor at all. The reprap limit switch might have needed more setup for bed levelling, but at least it worked reliably.
     
  3. pSimon

    pSimon Member

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    More testing - a sheet of black paper under the glass causes proper triggering.

    PCB too shiny?
     
  4. markoaurelije

    markoaurelije Active Member

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    Please check that the IR sensor (IR sensors PCB) is level with the glass, this is very important. I had issues until I made it level with the glass.
     
  5. pSimon

    pSimon Member

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    pretty sure it is, but I'll go over that again
     

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