Z-IR height is too high off the bed when printing



  • I have reset my IR Probe 10 times using the wiki page, it triggers the the height at 1.683mm.

    I set up the nozzle to just touch the paper with a little bit of drag, sent the code M564 S0 and then the G92 Z0 to zero the head, i then move the nozzle 5mm above the bed and the duet web control panel shows it at 5.00mm I then send the G30 S-1 to probe and this gives a trigger height of 1.683 in the g-code console panel, i repeat this about 3 times to get a consitant 1.683 this then displays in the console and then displays the 6.683 in the web control panel.

    I edit the System Editor and edit the config.g file. Set the Z parameter in the G31 command to the trigger height of 1.683 that was reported. Save the file.

    But i do not seem to have a config-overide.g file anywhere.

    I then go to print, it then homes the nozzle and the panel dispalys 6.683mm after moving the bed down 5mm, when i go to actual printing mode, the nozzle distance is about 1.683mm above the bed ?? and the print then fails to stick to the bed as the nozzle is too high.

    Can anyone please help.


  • administrators

    I suspect that you are homing Z using a G1 S1 Z command instead of a G30. Please post your homez.g and homeall.g files, and see https://duet3d.dozuki.com/Wiki/ConfiguringRepRapFirmwareCartesianPrinter#Section_Homing_Z_using_a_Z_probe.



  • I am also having the same problem, I always seem to never get a true grasp on how to set the Z offset correctly. I am noticing if I hold a thick piece of paper up to the sensor the LEDs go off twice, once at a distance of 20mm approx. and a second time at which I would assume is the correct height that I am getting, 1.649mm. I updated to 2.03 firmware and now it is working similar to Shaunppl. I am using Phaedrux's Z probe macro and getting 1.649mm consistently when the IR probe is triggered. Here are my files, currently in the config.g the offset is set to 0mm.

    7_1564018675514_homez.g 6_1564018675514_homey.g 5_1564018675514_homex.g 4_1564018675514_homeall.g 3_1564018675514_home.g 2_1564018675514_config-override.g 1_1564018675513_config.g 0_1564018675513_bed.g



  • @underdonesushi

    What is your bed surface? IR probe performance can be affected by the bed surface reflectivity. Especially if there are patterns or logos on it.

    I notice that in your homez and homeall you aren't using the same location to probe the bed, and the locations you are using are not in the center of the bed. For best results you should move the probe to the center of the bed for establishing the Z height. Ideally it should be the same spot you've used to measure your trigger height.

    Homez

    G1 X15 Y-10 F9000 ; go to first probe point
    G30               ; home Z by probing the bed
    

    Homeall

    G1 X15 Y15 F9000        ; go to first bed probe point and home Z
    G30                     ; home Z by probing the bed
    

    Your G31 command in config.g lacks any X and Y offsets for the probe.
    G31 P500 X0 Y0 Z2.0 This would only be accurate if your probe is also your nozzle. You didn't mention what your probe type is, but this thread is about an IR probe, so if we assume that's what you have, then you should measure the distance in X and Y between the nozzle and the probe and enter it into G31.

    https://duet3d.dozuki.com/Wiki/Test_and_calibrate_the_Z_probe#Section_Measuring_Probe_X_Y_Offset

    I also see that you are loading the heightmap in config.g. This isn't recommended because you haven't yet determined what Z0 is at bootup. Remove G29 S1 from config.g and add it either to the end of your homez and homeall, or add it to the slicer start gcode after the g28.

    https://duet3d.dozuki.com/Wiki/Using_mesh_bed_compensation#main



  • @phaedrux Bed surface - Similar to matte finish (no logo) to Buildtak but has a magnetic sheet underneath, Easy-Peelzy - https://www.kickstarter.com/projects/1011650524/easy-peelzy?ref=nav_search&result=project&term=easy peelzy

    homez + homeall - I am still learning how to correctly code the duetwifi but, you are saying the two areas thare are bold should be exactly the same? I am using X15 Y15 because the IR Probe is on the front of my E3D v6 and so I wanted to make sure it was reading a consistent part of the bed.

    G31 Command - I had the printer working with the IR probe before moving it, I don't think I had a value inputted in the G31 P500 X0 Y0 Z2.0

    Heightmap - Yes I had the printer working with the heightmap, could this be throwing it off? To remove the heightmap and start over would I just delete the heightmap.g?

    thanks phaedrux



  • @underdonesushi said in Z-IR height is too high off the bed when printing:

    @phaedrux Bed surface - Similar to matte finish (no logo) to Buildtak but has a magnetic sheet underneath, Easy-Peelzy - https://www.kickstarter.com/projects/1011650524/easy-peelzy?ref=nav_search&result=project&term=easy peelzy

    It's hard to tell from the photos but that does look like a suitable surface for the IR probe. It isn't overly shiny by the looks of it and no graphics on it.

    homez + homeall - I am still learning how to correctly code the duetwifi but, you are saying the two areas thare are bold should be exactly the same? I am using X15 Y15 because the IR Probe is on the front of my E3D v6 and so I wanted to make sure it was reading a consistent part of the bed.

    Yes, you should alter the G1 X Y command that comes before the G30 to move the probe into the center of the bed before probing, and that location should be the same in both homeall and homez.

    G31 Command - I had the printer working with the IR probe before moving it, I don't think I had a value inputted in the G31 P500 X0 Y0 Z2.0
    You need to measure the distance between the probe and the nozzle in X and Y and enter the values in G31 so that the offset between the nozzle and probe can be taken into account. See the link above for description of exactly how to go about it.

    Heightmap - Yes I had the printer working with the heightmap, could this be throwing it off? To remove the heightmap and start over would I just delete the heightmap.g?
    Every time you run G29 the heightmap.g is replaced with a new one. G29 S1 loads the saved heightmap.

    What I am saying you should do is remove the G29 S1 from config.g so it isn't loading the heightmap right at boot up. Instead put G29 S1 at the end of homeall and homez after the G30. That way your Z position is known before the heightmap is loaded. That should help correct your Z height being off.

    thanks phaedrux

    Hope that helps.



  • @phaedrux

    Bed surface - I don't think the bed surface is the problem at all.

    Homez.g -
    0_1565544073906_homez.g

    Homeall.g -
    0_1565544108688_homeall.g

    Heightmap - I removed the heightmap file and disabled it in the config.g correctly I think...

    I have been working on and off on this Z offset problem for months now, literally no clue. I have been using this one today, I need this to work it is killing me not being able to print anything. I am at a loss, I had it working somehow then moved and reconnected it to the wifi and it just reads too high now @Phaedrux ---https://duet3d.dozuki.com/Wiki/Test_and_calibrate_the_Z_probe#Section_Calibrate_the_Z_probe_trigger_height

    I noticed when I do M500 P31 and check my config.override.g I get this in the Z-probe section, It seems to be reading 3 tools?
    0_1565544250358_config-override.g

    I have also included my config.g file --- I took a little inspiration from your layout.
    0_1565544976932_config.g



  • @underdonesushi said in Z-IR height is too high off the bed when printing:

    I noticed when I do M500 P31 and check my config.override.g I get this in the Z-probe section, It seems to be reading 3 tools?

    Hmm, I'm not too sure about that. Are you using M500 G31 in your workflow, or just for testing? I'd probably delete these lines from config-override.

    What do you have in your slicer start gcode?



  • @phaedrux I think I figured it out... I bought sensor #1 Feb 28th, 2018 and sensor #2 on August 1st, 2018.
    Had always used sensor #1 and had it working for approx, 2 months? Then I moved and it stopped working. Just switched the sensor out with #2 to see if it would work and it activated correctly above the bed surface and is printing which is a HUGE relief. Thank you so much guys for your help, I will let you know if this was the end all be all solution.

    @dc42 Sensor #1 was activating the lights twice, once at approximately 6mm above the bed and if I turned axis limits off it activated again at the correct height. Is there any reason for this or is it a dud sensor? I can take a photo of both next to each other for you. They both say they are V1.3 on the rear but the #2 board has no diagnosis holes right of the chip, and the holes (right of R1 and right of R3 are soldered up).

    Thanks again!

    Ian


 

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