Anycubic Kossel plus - Bed Leveling errors with BLTouch



  • Hey guys,

    I modified a Anycubic Kossel Plus Delta Printer as I wasnยดt happy with the results it printed (now I would be happy to get these results back ๐Ÿ˜ง )
    So I decided to give it a better mainboard than the old Trigorilla 8bit board and optimize the construction. My choice fell on a DuetWifi board which I definitly love cause its a huge step forward.

    I liked to use a BLtouch to make it easier to level the bed as it seemd to be a good probe with good accuracy.

    0_1527009511989_20180522_191542b.jpg
    Thats how I mounted the BLtouch to the Delta effector of the Kossel. (its 37mm away from the nozzle, which is quite a lot in my eyes ๐Ÿ˜• )

    I configured the config.h file and added the code snippets for the BLtouch to work.

    At first I set the G31 params and determined the probes z offset which worked good and reliable, but after i restarted the printer and made a new G30 the nozzle is about 0.2mm too low ๐Ÿ˜ž

    My routine was:

    1. Command the print head down in small steps until the nozzle just touches a piece of paper
    2. G92 Z0
    3. Command the nozzle up 5mm (G1 Z5)
    4. Send G30 S-1 to probe the bed without resetting the Z=0 position
    5. Read off the Z height from the web interface and insert it in G31 params in config.h

    But after each homing and afterwards probing Z the nozzle ist about 0,2mm too deep.

    Hope you can help me and sorry for my english ๐Ÿ™‚
    Yours Lukas

    ; Configuration file for Duet WiFi (firmware version 1.20 or newer)
    ; executed by the firmware on start-up
    
    ; General preferences
    G90                                      ; Send absolute coordinates...
    M83                                      ; ...but relative extruder moves
    
    ;*** The homed height is deliberately set too high in the following - you will adjust it during calibration.
    M665 R135 L273 B115 H299 X0.0 Y0.0 Z0.0     ; Set delta radius, diagonal rod length, printable radius and homed height
    M666 X0 Y0 Z0 A0.0 B0.0        ; Put your endstop adjustments here, or let auto calibration find them
    
    ; Network
    M550 PDelta One                          ; Set machine name
    M552 S1                                  ; Enable network
    M587 S"WLAN1-4A3M7Q" P"****" ; Configure access point. You can delete this line once connected
    M586 P0 S1                               ; Enable HTTP
    M586 P1 S0                               ; Disable FTP
    M586 P2 S0                               ; Disable Telnet
    
    ; 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 Y80 Z80 E96                      ; Set steps per mm
    M566 X1200 Y1200 Z1200 E1200             ; Set maximum instantaneous speed changes (mm/min)
    M203 X18000 Y18000 Z18000 E1200          ; Set maximum speeds (mm/min)
    M201 X1000 Y1000 Z1000 E1000             ; Set accelerations (mm/s^2)
    M906 X1000 Y1000 Z1000 E1000 I60         ; Set motor currents (mA) and motor idle factor in per cent
    M84 S30                                  ; Set idle timeout
    
    ; Axis Limits
    M208 Z0 S1                               ; Set minimum Z
    
    ; Endstops
    M574 X2 Y2 Z2 S1                         ; Set active high endstops
    
    ; Z-Probe
    M558 P9 H5 F400 T4000 X0 Y0 Z1 B1        ; Disable Z probe but set dive height, probe speed and travel speed
    G31 P25 X0 Y-37 Z2.648                      ; Z probe trigger value, offset in relation to nozzle. And trigger height adjustment
    M557 R115 S20                            ; Define mesh grid
    
    ; Heaters
    M305 P0 T100000 B4138 C0 R4700           ; Set thermistor + ADC parameters for heater 0
    M143 H0 S120                             ; Set temperature limit for heater 0 to 120C
    M305 P1 T100000 B4725 C7.060000e-8 R4700 ; Set thermistor + ADC parameters for heater 1
    M143 H1 S280                             ; Set temperature limit for heater 1 to 280C
    
    ; BLTouch - Heaters
    M307 H3 A-1 C-1 D-1                      ; Disable the 3rd Heater to free up PWM channel.
    
    ; Fans
    M106 P0 H-1                              ; Set fan 0 value, PWM signal inversion and frequency. Thermostatic control is turned off
    M106 P1 S1 I0 F500 H1 T45                ; Set fan 1 value, PWM signal inversion and frequency. Thermostatic control is turned on
    M106 P2 S1 I0 F500 H1 T45                ; Set fan 2 value, PWM signal inversion and frequency. Thermostatic control is turned on
    
    ; Tools
    M563 P0 D0 H1                            ; Define tool 0
    G10 P0 X0 Y0 Z0                          ; Set tool 0 axis offsets
    G10 P0 R0 S0                             ; Set initial tool 0 active and standby temperatures to 0C
    
    ; Automatic saving after power loss is not enabled
    
    ; Custom settings
    M501                                     ;override settings 
     
    ; Miscellaneous
    T0                                       ; Select first tool
    


  • Try a G32, full calibrate. Then save probe calibration results with M500.

    And be sure you have an M501 near the end of config.g to load those saved results.



  • Thanks for your reply Danal,

    I tried the g32 command and it definitly reduced the height error .
    I didnt change anything to the config.h and the nozzle is now 0.1mm too deep at the paper test .

    I already have the M501 at the end of my config.h file.

    my probe offset is set to Z2.52 but after G30 S-1 DWC shows Z Position 2.57 ist this the normal behavior ??


  • administrators

    @hardware-crash, when you run auto calibration, what deviation does it report?

    It's worth checking the Z probe trigger height at various XY coordinates, to see if you are getting a consistent trigger height.



  • @hardware-crash said in Anycubic Kossel plus - Bed Leveling errors with BLTouch:

    I didnt change anything to the config.h and the nozzle is now 0.1mm too deep at the paper test .

    Take a look at config_override.g to see the results of the G32 M500.

    my probe offset is set to Z2.52 but after G30 S-1 DWC shows Z Position 2.57 ist this the normal behavior ??

    Yes, the purpose of the G30 S-1 command is to have the machine measure your true trigger height. You should be using that command as part of a process, shown here:

    https://duet3d.dozuki.com/Wiki/Calibrating_a_delta_printer#Section_Connecting_and_configuring_the_Z_probe

    In fact, follow that procedure from that point onward, including generating a new bed.g file; at the end of that whole process, you should have a calibrated printer, and be able to re-calibrate in moments anytime you wish.



  • I think i might have found a point that could have caused the problems with the BLTouch.
    The mounting plate for the BLTouch (found on thingiverse), which is screwed to the fan collides with the push rods when it comes near to the towers of Y & Z axis. I commanded the effector to the positions directly under the Y & Z towers and the rods push quite hard against the BLTouch mount. Could this cause autocalibration to fail or wrong values ?

    Now I removed the Bltouch and ordered a precision piezo probe.
    I will try to setup the delta manually for now ๐Ÿ™‚



  • @hardware-crash said in Anycubic Kossel plus - Bed Leveling errors with BLTouch:

    I think i might have found a point that could have caused the problems with the BLTouch.
    The mounting plate for the BLTouch (found on thingiverse), which is screwed to the fan collides with the push rods when it comes near to the towers of Y & Z axis. I commanded the effector to the positions directly under the Y & Z towers and the rods push quite hard against the BLTouch mount. Could this cause autocalibration to fail or wrong values ?

    Yes, in a couple of different ways.


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