Delta Printer Nozzle height


  • administrators

    1. Have you checked that there isn't a M665 command in config-override.g that is overriding the one in config.g?

    2. Are you running auto calibration before printing? If so then it's the G31 trigger height that you need to adjust.



  • Hi,
    Where would I find the config-override.g file, I do not see one.
    I am running auto -cal before printing (that's what I should do?)
    The G31 trigger height? the Z setting is at -0.1, but I read that should be a negative number, I am using the Smart Effector.
    "If you are using the nozzle as a probe (for example with a peizo or switch that the hotend had a travel distance to trigger then remember the Z offset needs to be negative (ie the probe triggers under Z0"



  • config-override.g is in the same directory as all system files, including config.g

    config-override.g is created when you do an M500 (store parameters). If you've never done one, it won't exist.



  • Do I need it?



  • no you dont need it and you prob ably need to increase the H parameter in the M665 if your hitting the bed when probing also increase the Dive hight in the M558 command (You can adjust this back down once you have it calibrated and put all the calibration data into the Config.g



  • Not hitting the bed during probing, only when the print starts. Would I still increase H parameter in the M665.



  • no you should adjust the Z Param in the G31 to compensate


  • administrators

    Try running auto calibration (G31) after homing and then not homing again before the print starts. So if there is a G28 command in your slicer start gcode, either remove it (and then home and run calibration manually before printing a file), or put G31 G32 after the G28 line.

    It's best to heat the bed up to temperature and the hot end either up to temperature of most of the way there before running auto calibration.



  • @Dougal1957:

    no you should adjust the Z Param in the G31 to compensate

    Does a negative number for Z mean closer or further away from the bed



  • @dc42:

    Try running auto calibration (G31) after homing and then not homing again before the print starts. So if there is a G28 command in your slicer start gcode, either remove it (and then home and tun calibration manually before printing a file), or put G31 after the G28 line.

    It's best to heat the bed up to temperature and the hot end either up to temperature of most of the way there before running auto calibration.

    This had the same outcome.



  • I pretty much always use autocalibration then use a piece paper to set my g92 z0 nozzle height. Perfect first layer every time but takes an extra minute when I start up. That way I don't have to worry about it after that.



  • @Billhc83:

    I pretty much always use autocalibration then use a piece paper to set my g92 z0 nozzle height. Perfect first layer every time but takes an extra minute when I start up. That way I don't have to worry about it after that.

    I do not see a G92 line of code. Do I just add it Where?
    Also if you don't mind me asking,
    You perform auto calibration then you set the nozzle height by the jog controls with a piece of paper.
    So when that is done where do you get the height numbers from and how do they get in the code.
    Thanks



  • This is meant to be manually done once delta calibration is finished.

    Jog the head to the bed until it just grabs a piece of regular paper. Send g92 z0 via pronterface or DWC. Upload and print. I only do this once when I start the machine.


  • administrators

    @Quadcells:

    @dc42:

    Try running auto calibration (G31) after homing and then not homing again before the print starts. So if there is a G28 command in your slicer start gcode, either remove it (and then home and tun calibration manually before printing a file), or put G31 after the G28 line.

    It's best to heat the bed up to temperature and the hot end either up to temperature of most of the way there before running auto calibration.

    This had the same outcome.

    There was a typo in my post, it should have been G32 not G31.


  • administrators

    @Billhc83:

    This is meant to be manually done once delta calibration is finished.

    Jog the head to the bed until it just grabs a piece of regular paper. Send g92 z0 via pronterface or DWC. Upload and print. I only do this once when I start the machine.

    It should not be necessary to set the height manually using G92, unless the Z probe is not giving consistent results.



  • @dc42:

    @Quadcells:

    @dc42:

    Try running auto calibration (G31) after homing and then not homing again before the print starts. So if there is a G28 command in your slicer start gcode, either remove it (and then home and tun calibration manually before printing a file), or put G31 after the G28 line.

    It's best to heat the bed up to temperature and the hot end either up to temperature of most of the way there before running auto calibration.

    This had the same outcome.

    There was a typo in my post, it should have been G32 not G31.

    I tried again and the nozzle still digs into the bed.
    With the S3D slicer should the Z setting under Update Machine Definition match what is in the H parameter in the M665


  • administrators

    The Z setting in the slicer only affects the size of the part it will slice without warning you. Setting it about the same as the M665 H parameter is good.

    Try running auto calibration, then put a sheet of ordinary 80gsm paper on the bed and command the nozzle to X0 Y0 Z0. The nozzle should grip the paper, but not too tightly. If it grips tightly, then that suggests that the Smart Effector is triggering at a height of less than the -0.1mm that you have set in the G31 command. In which case:

    • If the height at X0 Y0 is correct but away from X0Y0 the nozzle digs into the bed, that suggests a calibration problem. What deviation does auto calibration report?
    • Check that you are using the recommended probing speed, F1000 in the M558 command.
    • Are you using the default Smart Effector sensitivity, or have you reduced it?
    • What bed material are you using? With a softer bed the trigger height may be below -0.1mm
    • Check that your G31 command to set the trigger height to -0.1mm is after the M558 command in config.g
    • You can change the G31 trigger height, e.g. using G31 Z-0.2 instead of Z-0.1 will raise the nozzle by 0.1mm.

    HTH David



  • Hi David,

    "- If the height at X0 Y0 is correct but away from X0Y0 the nozzle digs into the bed, that suggests a calibration problem. What deviation does auto calibration report?"
    Deviation before= 1.853 after 1.581

    "- Check that you are using the recommended probing speed, F1000 in the M558 command."
    Yes I am using the recommended probing speed of F1000 in the M558 command.

    "- Are you using the default Smart Effector sensitivity, or have you reduced it?"
    I did not change this parameter.

    "- What bed material are you using? With a softer bed the trigger height may be below -0.1mm"
    The bed is tool plate aluminum 305mm x 305mm x 6mm with a 120v silicone heater attached underneath and a 300mm x 300m x 1mm build platform sticker like this one: https://www.amazon.com/HICTOP-Printing-Surface-Heated-300x300mm/dp/B074QM92S7/ref=sr_1_2?ie=UTF8&qid=1520960475&sr=8-2&keywords=300mm+x+300mm+build+platform+sticker

    "- Check that your G31 command to set the trigger height to -0.1mm is after the M558 command in config.g"
    It is.

    "- You can change the G31 trigger height, e.g. using G31 Z-0.2 instead of Z-0.1 will raise the nozzle by 0.1mm."
    I ran the auto calibration, put a piece of paper down and sent G1 X0 Y0 Z0 via the DWC. The paper was in good. I then used the PanleDue interface controls to move the nozzle in the +Z direction at .5 increments until there was enough space for the paper to be just grabbing the nozzle, Z= +2.5. I added that number to the G31 trigger height which came to -2.6 and changed G31 Z-.1 to Z-2.6.

    I have printed 2 20mm cubes measuring Z=20.01mm X=22.61mm Y=22.65mm and Z=20.01mm X=22.58mm Y=22.62mm.
    The L parameter in M665 is 400.97 which is on the label attached to the arms that I bought from Haydn Huntley.

    Can I leave such a large value in the G31 Z parameter, Is it recommended to not this type of build platform sticker.
    Thanks again for all your help everyone! Not done but I think it is looking promising.


  • administrators

    I think the problem is that your calibration deviation of 1.581mm is much too high. With a Smart Effector and a good build, you should easily be able to get it below 0.1mm.

    Please check the points at https://duet3d.dozuki.com/Wiki/Calibrating_a_delta_printer#Section_Make_sure_your_build_is_accurate and see if you can spot anything wrong. Also please post your bed.g file.



  • @dc42:

    I think the problem is that your calibration deviation of 1.581mm is much too high. With a Smart Effector and a good build, you should easily be able to get it below 0.1mm.

    Please check the points at https://duet3d.dozuki.com/Wiki/Calibrating_a_delta_printer#Section_Make_sure_your_build_is_accurate and see if you can spot anything wrong. Also please post your bed.g file.

    Here is the bed.g file, I will have to check my build later, just came in after clearing our 20 inches of snow off the cars and driveway and I am beat.

    ; bed.g
    ; called to perform automatic delta calibration via G32
    ;
    ; generated by RepRapFirmware Configuration Tool on Thu Mar 08 2018 15:49:43 GMT-0500 (Eastern Standard Time)
    M561 ; clear any bed transform
    G28 ; home all towers
    ; Probe the bed at 3 peripheral and 0 halfway points, and perform 3-factor auto compensation
    ; Before running this, you should have set up your Z-probe trigger height to suit your build, in the G31 command in config.g.
    G30 P0 X0 Y104.9 H0 Z-99999
    G30 P1 X90.85 Y-52.45 H0 Z-99999
    G30 P2 X-90.85 Y-52.45 H0 Z-99999
    G30 P3 X0 Y0 H0 Z-99999 S3
    ; Use S-1 for measurements only, without calculations. Use S4 for endstop heights and Z-height only. Use S6 for full 6 factors
    ; If your Z probe has significantly different trigger heights depending on XY position, adjust the H parameters in the G30 commands accordingly. The value of each H parameter should be (trigger height at that XY position) - (trigger height at centre of bed)


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