Need help with Auto bed leveling.

Hi there,

I've moved to inductive Z-probe recently and decided to activate auto bed leveling feature. I've spend a day trying to understand and configure it. But no luck. And I really need your help.
Here's what I have:
- Repetier firmware 0.92.9.
- probe offsets are 20/60 (yes, sensor is bg, I had to move it this far, moves with hotend).
- Table dimensions (keeping probe above table) 280*160mm
- ENDSTOP_Z_BACK_ON_HOME 10
- Z_PROBE_BED_DISTANCE 10
- Z_PROBE_HEIGHT 2.2
- BED_LEVELING_METHOD n*n grid, grid size 5, probe pos.1 20/60, probe pos.2 280/60, probe pos.3 20/160.

If I home all axis, keep hotend at 0/0, and try to run G32, hotend hits endstops making mechanics crack. If after homing I move hotend to, i.e. 100/100 (X/Y), than running G32 makes hotend move in probe coordinates 20/60 (which is physically hotend and table 0/0).
Why does it forces hotend to move beyond 0/0 after homing? If I put first probe pos.1 to 0/0, it also tries to break the limits despite of hotend placement.

Another thing I don't understand is:
Having ENDSTOP_Z_BACK_ON_HOME 10 makes print run (tried on dry run) 10mm above the table. Making ENDSTOP_Z_BACK_ON_HOME 0 helps. But with it in 0, I have to manually move Z axis to prevent plastic blob on hotend.

Comments

  • First, i recoend using the dev version of firmware, many improvements in probing .

    Use homing option z up X Y Z this will open a section in config tool where you can set the X Y coords for z homeing.
    setting ENDSTOP_Z_BACK_ON_HOME 10  artifitially moves the Z0 position to 10mm off the endstop trigger point.

  • MartinH said:
    First, i recoend using the dev version of firmware, many improvements in probing .

    Use homing option z up X Y Z this will open a section in config tool where you can set the X Y coords for z homeing.
    setting ENDSTOP_Z_BACK_ON_HOME 10  artifitially moves the Z0 position to 10mm off the endstop trigger point.

    Sir,

    Option Z up X,Y, preheat,Z opens XY Homing pos. for Z option. By default those are 999999. But note says - [mm / 999999 = do not change]. So I asume these coords shouldn't be changed?
    And for the ENDSTOP_Z_BACK_ON_HOME 10 - how could I make Z axis to drop table 10mm after Z homing without ruining Z0?
  • yes you can change them, then nozzle will move up the set amount and move to the X Y co'ords that you set instead of the 999999
  • I run homing and bed levelling from the script option buttons,

    homing just send  G28

    levelling, i like to make sure the sensor is over the bed before it starts ,so i set in button 2
    G1 Z10 F700
    G1 X30 Y30 F1200
    G32
  • MartinH said:
    I run homing and bed levelling from the script option buttons,

    homing just send  G28

    levelling, i like to make sure the sensor is over the bed before it starts ,so i set in button 2
    G1 Z10 F700
    G1 X30 Y30 F1200
    G32
    Can you share how you probe offsets and bed leveling method/probe positions configured?
    About homing and lifting Z axis a bit (to keep nozzle clean from plastic blob) - is parameter ZHOME_PRE_RAISE_DISTANCE (appeared when I select Z up X,Y, preheat,Z) what I'm looking for?
  • ZHOME_PRE_RAISE_DISTANCE    this will raise Z before it does the homing, so Z allways needs to have this amount of clearance (below Z max)
    G28 ends the homing with a move to X0 Y0 Z0

    You could use one of the preset buttons and do

    G28
    G1 Z5

  • Ok, I've flashed dev firmware. Left everything as it was, except homing procedure as was stated by MartinH. ZHOME_PRE_RAISE_DISTANCE is 10mm. While homing I get message in repetier, that  hotend is trying to reach unavailable coordinates (-20, -60 - just same as z-probe offset. But why? Should I change X_MIN_POS and Y_MIN_POS to probe offset coords? Why with activated probe all coordinates conects to probe, not hotend?
  • No, you need to set z homing position to 20, 60 to make it work. Guess you home xy being at 0,0 and then it activates probe which means moving to -20,-60 from 0,0 and that is not possible.

    Select a homing order with preheat and set preheat temperature 0. That option also allows setting z homing position which is what you need.
  • Thanks, that helped.
    Few more questions:
    - Tools-Bed height map makes Host to crash. Runing with 5*5 points. Crushes on about half way done.
    - Z_probe_height -1.000. I have inductive probe and alu table. When I try to home Z axis, it crushes into table on first try, but that stops on the correct height. How to prevent this first time probing from breacking my table?:) Looks like it ignores Z_Probe_Height. 
  • Moved z-probe lower, looks like it works.
Sign In or Register to comment.