Mesh compensation: Skipping grid points



  • Hi all,

    I have a Duet installed on a Tornado and everything works relatively ok. One problem I find, though is the mesh definition. It always skips the top right points as the console outputs:

    Warning: Skipping grid point (260.0, 200.0) because Z probe cannot reach it
    

    even though there is room enough for the probing.

    Any ideas in what could it be?

    Thanks in advance!


  • Moderator

    It would be in relation to the defined size of the bed, the defined mesh grid, and the probe offsets. Without knowing these values, it's hard to say.

    If it thinks it can't reach it, but it actually could, then your offsets or mesh is not accurately defined I would think.



  • @Phaedrux said in Mesh compensation: Skipping grid points:

    It would be in relation to the defined size of the bed, the defined mesh grid, and the probe offsets. Without knowing these values, it's hard to say.

    If it thinks it can't reach it, but it actually could, then your offsets or mesh is not accurately defined I would think.

    right you are, I think. Here is the config.g file. The Tevo Tornado is a 300x300 machine

    ; Configuration file for Duet WiFi (firmware version 1.21)
    ; executed by the firmware on start-up
    ;
    ; generated by RepRapFirmware Configuration Tool on Mon Feb 04 2019 17:03:09 GMT+0100 (Central European Standard Time)
    
    ; General preferences
    G90                                                ; Send absolute coordinates...
    M83                                                ; ...but relative extruder moves
    
    ; Network
    M550 P"Tevo Tornado"                               ; Set machine name
    M552 S1                                            ; Enable network
    
    M586 P0 S1                                         ; Enable HTTP
    M586 P1 S0                                         ; Disable FTP
    M586 P2 S0                                         ; Disable Telnet
    
    ; Drives
    M569 P0 S0                                         ; Drive 0 goes backwards
    M569 P1 S0                                         ; Drive 1 goes backwards
    M569 P2 S1                                         ; Drive 2 goes forwards
    M569 P3 S0                                         ; Drive 3 goes backwards
    M350 X16 Y16 Z16 E16 I1                            ; Configure microstepping with interpolation
    M92 X80.00 Y80.00 Z400.00 E408.00                  ; Set steps per mm
    M566 X600.00 Y600.00 Z24.00 E300.00                ; Set maximum instantaneous speed changes (mm/min)
    M203 X15000.00 Y15000.00 Z1800.00 E3300.00         ; Set maximum speeds (mm/min)
    M201 X2000.00 Y2000.00 Z120.00 E10000.00           ; Set accelerations (mm/s^2)
    M906 X700.00 Y1200.00 Z1200.00 E800.00 I30         ; Set motor currents (mA) and motor idle factor in per cent
    M84 S30 
    
    ; Axis Limits
    M208 X0 Y0 Z0 S1                                   ; Set axis minima
    M208 X300 Y300 Z400 S0                             ; Set axis maxima
    
    ; Endstops
    M574 X1 Y1 S0                                      ; Set active low endstops
    
    
    M574 Z1 S2 	                                   ; Set endstops controlled by probe
    M558 P5 H5 F300 T6000   	   		   ; Set Z probe type to switch and the dive height + speeds
    
    G31 P500 X-43 Y-5 Z0.62                            ; 0.65 is the calculated  Set Z probe trigger value, offset and trigger height
                                                       ; The larger the number the closest it gets to the bed
                                                       ;i.e.  1.50 puts the nozzle closer to the bed than 1.20
    M557 X20:300 Y20:280 S30                           ; Define mesh grid
    
    ; Heaters
    M307 H0 B0 S1.00                                   ; Disable bang-bang mode for the bed heater and set PWM limit
    M305 P0 T100000 B4092 C0 R4700                     ; Set thermistor + ADC parameters for heater 0
    M143 H0 S95                                        ; Set temperature limit for heater 0 to 95C
    
    M305 P1 T100000 B4092 C0 R4700                     ; Set thermistor + ADC parameters for heater 1
    M143 H1 S260                                       ; Set temperature limit for heater 1 to 260C
    
    M307 H1 A471.8 C161.7 D5.2 V23.8 B0                ;Hotend Autotune  //Changed
    M307 H0 A90.0 C700.0 D10.0 V0.0                    ;Bed Autotune //Changed
    
    ; Fans
    M106 P0 S0 I0 F500 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 S0.45 I0 F500 H-1                          ; Set fan 2 value, PWM signal inversion and frequency. Thermostatic control is turned off
    
    ; 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 power saving
    M911 S10 R11 P"M913 X0 Y0 G91 M83 G1 Z3 E-5 F1000" ; Set voltage thresholds and actions to run on power loss
    
    ; Custom settings are not configured
    
    

  • Moderator

    @FelixH said in Mesh compensation: Skipping grid points:

    G31 P500 X-43 Y-5 Z0.62
    M557 X20:300 Y20:280 S30

    If your probe is -43mm from the nozzle, and the nozzle can only move to 300mm then the probe can't reach 300mm, hence the error.

    If you don't want the error, you can change the size of the mesh to account for that -43mm offset. That would allow you to increase the density within the reachable area if you wanted.



  • so, what I have to input on the M557 command is the position of the probe?. I thought the firmware would account for that... I'll try it first thing tomorrow, Thanks!


  • Moderator

    @FelixH said in Mesh compensation: Skipping grid points:

    I thought the firmware would account for that

    It does. It skips the points it can't reach.

    Subtract the probe offset from the mesh grid. 300-43=257


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