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Solved Bed leveler misses calibration points

Discussion in 'Troubleshooting' started by ronnieh2, May 11, 2020.

  1. ronnieh2

    ronnieh2 New Member

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    The nozzle always touches the bed while the extruder is warming up.
    But during calibration, some of the points are missed. Not all, just some.
    The location and number of failed points varies and has gotten more erratic with subsequent tries to print.

    This happened after I tightened a loose contact on the left limit switch.
    To make sure that the carriage was level, I manually adjusted carriage height, measuring height to the bed with a digital caliper. The top bar of the carriage is at 75mm off the bed at rest.

    I checked for other loose contacts on the limit switches by removing and re-inserting all four wires, and all are firmly attached.
     
    #1 ronnieh2, May 11, 2020
  2. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    The nozzle will go down until either it touches the bed (as indicated by one of the limit switches activating) or until the RAMPS thinks it did (because it got a signal that indicated a closed switch). Loose wire or bad switch are most likely, but a failed RAMPS board can do it to (just less likely)

    You can use the M119 in the gcode terminal to see what the endstops are reporting:

    M119
    Reporting endstop status
    x_min: open
    y_min: open
    z_min: TRIGGERED
    z_probe: open
    filament: open

    Try moving things around and get the endstop states. At least one is reading faulty.
     
    #2 mark tomlinson, May 11, 2020
  3. ronnieh2

    ronnieh2 New Member

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    M119 shows all axes reliably TRIGGERED when at HOME
    Moving X and Y only from HOME sometimes shows Z TRIGGERED and sometimes not.
    At one point, the carriage moved UP for both Z+ and Z- commands (M119 showed Z untriggered).
    Then, without warning, the extruder moved to the bed and M119 reported that Z was triggered.

    The external connections to the limit switches are solid.
    Does this lead to a fix or just confirm what I've observed without M119?
     
    #3 ronnieh2, May 11, 2020
  4. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    If the nozzle is off the bed and moving around it should never read Z home triggered. Otherwise you have a faulty switch, connection, wiring or RAMPS board.

    Once the switch is read as triggered it will ONLY go up and not down (because if the Z is triggered it must already be on the bed so it will not allow it to go down).
     
    #4 mark tomlinson, May 11, 2020
  5. ronnieh2

    ronnieh2 New Member

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    Fixed.
    Apparently, I had pushed on the left limit switch too hard when re-installing the over-tight spade connection.
    This apparently nudged the switch out of position.
    Loosening and retightening the switch mounting screws worked.
    Thanks for your encouragement.
     
    #5 ronnieh2, May 12, 2020
    mark tomlinson likes this.

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