Mesh bed leveling issues with IR Sensor



  • Hi

    I upgraded my cartesian printer (Ultimaker clone) from a capacitive sensor to IR sensor directly plugged into my Duet 2 Ethernet running Firmware 2.04.

    No issues setting up the sensor, nor calibrating it.

    But making a mesh bed leveling (G29) on a 25 points square surface (250 mm) always leads to a tilted bed from the front to the rear with a deviation of 1 mm or so from the front edge to the rear edge.

    Capture d’écran 2019-12-16 à 13.34.21.png

    I've done a careful manual bed leveling with the bed and nozzle at normal working temperature, on a clean glass plate with no coating over a black matte cardboard.

    So I am sure the bed is perfectly leveled against the gantry, but the probing gives a different view.

    The printhead is guided by 2 LM6UU on each axis which are in good conditions, so no tilt suspected.

    Has it something to do with temperature ?
    My previous capacitive sensor was having a bias with temperature and derives over the probing.

    Thanks for the feedbacks


  • administrators

    The IR sensor is not temperature-sensitive. The height map looks quite flat, so i think the bed surface is OK for the sensor.

    Can you provide some photos of your printer, so that I can see how the Y axis moves?

    In what direction and by how much is the sensor offset fro the nozzle?



  • Did you do the levelling following this guide?
    https://duet3d.dozuki.com/Wiki/Using_the_manual_bed_levelling_assistant

    If you run it a few times, are the numbers converging?



  • @gtj0 said in Mesh bed leveling issues with IR Sensor:

    https://duet3d.dozuki.com/Wiki/Using_the_manual_bed_levelling_assistant

    Sorry for the late reply

    I don't use the leveling assistant.

    I level my bed the old way, moving the nozzle close to the 3 adjusting screws, using a sheet of paper to fine tune.

    Doing the tuning twice is generally sufficient to have a good leveling.
    I will set up the manual assistant in the near future, at it will save me some time.



  • Sorry for the late reply, busy period till the holidays break.

    @dc42 said in Mesh bed leveling issues with IR Sensor:

    The IR sensor is not temperature-sensitive. The height map looks quite flat, so i think the bed surface is OK for the sensor.

    Yes the measurements are pretty repeatable.

    Can you provide some photos of your printer, so that I can see how the Y axis moves?

    My printer is a Mankati Full-scale XT Plus, really a Ultimaker 2 clone.
    Y axis is mounted on two linear ball bearings (LM6UU japanese industrial grade), side by side, on a 6 mm rod.
    So bearing is on a 38 mm length, minimizing the tilt of the printhead.
    Same on X axis.

    In what direction and by how much is the sensor offset fro the nozzle?

    The offset from the left nozzle is X + 41,2 Y + 11,25. Zero been on the nozzle tip.
    Only the rear of the printhead has sufficient room in order to keep the build volume.



  • @dc42 Is this mesh probing error being fixed in the 2,05 or 3 FW versions ?


Log in to reply