Bed leveling with 2 Z motors



  • Hi there,

    Corexy, 2 Z Motors @ Xmin and Xmax.
    does it matter which Motor is connected to Z or E1?

    Probe is the Mini ir probe.
    After leveling the bed via the Motors, is G29 mesh bed leveling possible?

    Thanks!


  • administrators

    @torro said in Bed leveling with 2 Z motors:

    Hi there,

    Corexy, 2 Z Motors @ Xmin and Xmax.
    does it matter which Motor is connected to Z or E1?

    It doesn't matter. You need to list the leadscrew coordinates in the M671 command in the same order as you list the Z motor drivers in the M584 command.

    Probe is the Mini ir probe.
    After leveling the bed via the Motors, is G29 mesh bed leveling possible?

    Yes.



  • Ok, then i will give the mesh bed leveling a second Chance...



  • Hi there,

    wired it all up and changed config and bed.g (see below)

    after G29, the compensation is finally working. i don´t know why, these are the same settings like i tried the last time where it doesn´t compensate... when i drive from x min, to x max, the Z motors are slightliy spinning.

    only change i found was the trigger height. last time, it was 0.45mm, now i measured 1.42mm.

    now, please see the heigt map. why is there so much difference? the 2 Z motors are not compensating

    0_1548961489783_heightmap.jpg

    When i send a few G30 S-1 @Xmin, there is a trigger heigt of 3.463 to 3.369
    @Xmax, G30 S-1 reports trigger heights of 2.394 to 2.4

    config.g

    ; Drives
    M569 P0 S1 ; Drive 0 goes forwards
    M569 P1 S1 ; Drive 1 goes forwards
    M569 P2 S1 ; Drive 2 goes forwards
    M569 P3 S1 ; Drive 3 goes forwards
    M350 X16 Y16 Z16 E16 I1 ; Configure microstepping with interpolation
    M92 X80.00 Y80.00 Z160 E420.00 ; Set steps per mm
    M566 X900.00 Y900.00 Z12.00 E120.00 ; Set maximum instantaneous speed changes (mm/min)
    M203 X30000.00 Y30000.00 Z4000.00 E4000.00 ; Set maximum speeds (mm/min)
    M201 X1500.00 Y1500.00 Z500.00 E10000.00 ; Set accelerations (mm/s^2)
    M906 X800.00 Y800.00 Z800.00 E800.00 I40 ; Set motor currents (mA) and motor idle factor in per cent
    M84 S30 ; Set idle timeout
    M584 X0 Y1 Z2:4 ; two Z motors connected to driver outputs Z and E1
    M671 X20:220 Y0:0 S5 ; leadscrews at left and right of X axis

    ; Axis Limits
    M208 X0 Y-1 Z0 S1 ; Set axis minima
    M208 X240 Y260 Z300 S0 ; Set axis maxima

    ; Endstops
    M574 X1 Y1 S0 ; Set active high endstops
    M574 Z1 S2

    ; Z-Probe
    M558 P1 H5 F120 T6000 ; Disable Z probe but set dive height, probe speed and travel speed
    G31 P500 X0 Y50 Z1.42
    M557 X20:220 Y50:250 S20 ; Define mesh grid

    bed.g:

    G28 ; home
    G30 P0 X20 Y120 Z-99999 ; probe near a leadscrew, half way along Y axis
    G30 P1 X220 Y120 Z-99999 S2 ; probe near a leadscrew and calibrate 2 motors

    anyone an idea?



  • Last test for Today.
    I increased the S Parameter to 10 in M671.
    Disabled the Motors and put a screw under one side of Z.
    G32 probes the 2 points. After the second probe, the bed made a correction in the correct way.
    Then i probed the bed again via G29.

    The height map looks like the one above...


  • administrators

    @torro, if you send multiple G32 commands to level the 2 motors, what results do you get? It's not unusual to find that it under-corrects (that's why we provide the M671 F parameter); but you should find that the corrections get smaller each time.



  • I'll try.



  • Hi there,

    It got better.
    Now, there´s a little problem with the heightmap. the window is black. when i click on "top view", the height map is displayed from top. when i try to rotate it, the window get´s black again. when i click the "reload heightmap" button, there is a message "file not found" in the black heightmap window.

    disabling/loading the heightmap via compensation menu didn´t help.


  • administrators

    Did you run G29 before viewing the height map? Levelling the bed from side to side using independent leadscrews will not generate one.

    I recommend that after running G32 to level the bed and before running G29, you do a single G30 probe at bed centre to re-establish the Z=0 position. You can do this at the end of bed.g.



  • Yes, i run G29 to generate a heightmap.
    at the moment, i do only a G32, no bed compensation.

    works good.



  • this leveling thing drives me crazy. it worked a few times. now, after mutliple G32, the nozzle is on one side of the bed too close, at the other side too far away (about 0,2mm)

    has anyone experience with the IR probe and a "pertinax" build plate?
    i don´t know, how pertinax is called in english, the translator calls it "synthetic resin bonded paper" or Paxoline/Bakelite.

    this stuff is great, but i think the probe has a problem with it.

    should the trigger height always be the same, no matter where i probe? (no compensation active)
    i have some differences on both sides. multiple probes at the same spot give always the exact same trigger height.
    i tested it with all lights in the room off. no difference.


  • administrators

    I suggest you measure the trigger height at different places on the bed to check that is it consistent enough.

    Do not use the 2.03beta1 firmware with G32 leadscrew bed levelling, it doesn't work properly.



  • No, it's not 2.03.

    Should the trigger height be the same, regardless where i measure?



  • I'll try to increase the M671 F Parameter.
    Is there a Limit? Or a recommendation?

    It's the last Chance for my leveling Story...
    going back to a normal Z endstop or maybe two


  • administrators

    @torro said in Bed leveling with 2 Z motors:

    No, it's not 2.03.

    Should the trigger height be the same, regardless where i measure?

    Yes, if it isn't then you won't get good results.



  • Ok, then i can forget the leveling. There are big differences. About 0.2mm when i Check the trigger height at different spots on the bed.

    I'm going to independent Z motors with 2 endstops.
    Just reading here and the guide on dozuki.
    New thread with a lot of questions will follow soon 😉



  • this seems more like issue you have to resolve because if your probe is malfunctioning it's better to just ditch it and get something else to probe.


 

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