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Cannot adjust nozzle distance from bed during print.

BleachworthyBleachworthy
in General
Hello I am having a problem with the distance between the nozzle and print bed. I have an i3 style printer with a melzi 2.0 board and an inductive Z probe. I have tried many ways to adjust this height but it seems that nothing works. It's as if the value "Z-probe height" is not accounted for when printing begins.

Initially, I lowered the sensor (to avoid bed-nozzle contact), lowered the Z axis until the probe triggered, loosened the probe, lowered Z until the nozzle was 0.1mm above the bed and adjusted the probe to just barely trigger. I should have been able to leave the offsets at 0 and the nozzle should be 0.1mm above the bed, correct? Apparently not, it was always too high to put a layer down correctly and it just squirts everywhere.


Right now when my probe triggers, the nozzle is 2.1mm above the bed. I specified 2.0 mm in the "Z-probe height" EEPROM field. When it homes, it moves 2mm down after probe trigger, and rises back up. When I try to print, the nozzle is 4+mm off the bed.

What am I doing so wrong? Z-probe height is the correct field to edit to change the nozzle to bed relationship, right?

Thanks for the help!

Comments

  • RepetierRepetier
    Make sure bed coating is set to 0. Z-Probe height is what makes the difference. But set always check endstops off as your inductive probe will trigger in bottom range and might prevent moves there.

    I'm not sure how you do your z leveling. If you use it as z min trigger there are several conditions to be met and you need the dev version which has more fixes for this complicated homing procedure.

    A much easier and better solution is of course to use z max homing.
  • BleachworthyBleachworthy
    Bed coating is set to 0, it was a setting I didn't recognize immediately so I left it alone. Dare I ask what z max homing is? Where can I find the dev version and do i need to do anything about adjusting said fixes for the homing procedure? I am using it as the Z min and found success with it in marlin but I was driven away by fatally bad heater controls.

    My Z leveling has consisted of working the nozzle from one point to another on the bed while adjusting the 4 corner screws to fit a sheet of A4 paper between the nozzle and bed.

    You might be on to something with the check all endstops thing, I'm going to tear back into the code and turn that off in a little bit. You're probably right that the Z endstop trigger is stopping it from moving Z any lower, thus preventing my nozzle from going down to the bed. damn that makes sense i hope you are right!
  • BleachworthyBleachworthy
    Repetier said:
    Make sure bed coating is set to 0. Z-Probe height is what makes the difference. But set always check endstops off as your inductive probe will trigger in bottom range and might prevent moves there.

    I'm not sure how you do your z leveling. If you use it as z min trigger there are several conditions to be met and you need the dev version which has more fixes for this complicated homing procedure.

    A much easier and better solution is of course to use z max homing.
    Ok, so that seems to have been the issue, but now when I g32 for auto-leveling it sends y towards 0, x towards 0 and Z away from 0 and then crashes against whatever endstop it hits first, then a critical error is given in repetier host. The "always check endstops" option is the only thing modified, and auto-leveling works without it on.


    Maybe you could answer this for me since I plan to upgrade soon... What control board is most reliable/compatible with your software? I really feel like this melzi board is a big limitation in trying to have an auto-leveling machine, what do you think about that statement?

    Thanks again for the help!
  • RepetierRepetier
    Melzi has severl special problems I do not really like, so other board can surely improve.
    I like my radds boards with due for the extra speed benefit. But there are many other boards also working well.

    zmax homing means you have a z max endstop and home to that direction. But z min homing should also work. dev version is available also from config tool. Just select the dev version on first tab.

    G32 should not move to 0,0 unless you have set that as probing coordinates, but that might be impossible depedning on z probe offset. That is also one of the problems with homing with z probe. You need homing order xy preheat z so that you can z test coordinates so activating z probe with offset is possible.
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