First try on BLTouch: Bed surface too close to nozzle



  • I have problems achieving a good first layer on my Ender-5 rebuild without hacks. When I perform a mesh bed compensation with correct offset, the first layer is too flat/bed too close to the nozzle. It seems, the problem disappears when I either reduce the offset in G31 or enhance the distance of the the Switch when homing Z by 0.5 mm. However, then after mesh bed compensation the z-plane has an offset of 0.5 mm from the bed vertices. So the result looks blue which seems not so nice but is correct since I increased the distance.

    Is there another way to setup the distance of the nozzle to the print bed?



  • did you home again before doing a mesh bed leveling?



  • @veti
    yes, I always home before mesh bed comp. So far I only have tested this feature with my Deltas. There it just always worked out of the box. On the other hand, they use a piezo.



  • How are you homing?
    Can you post your config.g and homing files?
    Firmware version?



  • The z endstop switch is 2.0 mm too early. Means the nozzle is 2 mm below surface.
    This is why I use the G1 to position the nozzle to the bed plane,
    followed by G92 to zero the coordinate system.
    In my case I additionally move the bed 0.5 mm down. This explains the 2.5 mm.

    alt text

    homeall.g

    ; BLTouch prep so we don't catch the probe pin on the edge of the bed
    ;
    M280 P3 S160 I1 ; Alarm Release and Push-Pin UP just in case it's in alarm and deployed
    M402 ; Retract probe just in case it's down

    ; generated by RepRapFirmware Configuration Tool v2 on Sat Mar 23 2019 15:12:34 GMT+0100 (Mitteleuropäische Normalzeit)
    G91 ; relative positioning
    G1 Z5 F6000 S2 ; lift Z relative to current position
    G1 S1 X-215 Y-215 F1800 ; move quickly to X or Y endstop and stop there (first pass)
    G1 S1 X-215 ; home X axis
    G1 S1 Y-215 ; home Y axis
    G1 X5 Y5 F6000 ; go back a few mm
    G1 S1 X-215 F360 ; move slowly to X axis endstop once more (second pass)
    G1 S1 Y-215 ; then move slowly to Y axis endstop
    G1 S1 Z-210 F1800 ; move Z down stopping at the endstop
    G1 S0 Z2.5 ; move bed 2 mm down
    G90 ; absolute positioning
    G92 Z0 ; set Z to axis minimum (you may want to adjust this)
    G1 S0 Z5
    G1 S0 X15 ; move nozzle 15 mm left
    G92 X0 ; set X to axis minimum (you may want to adjust this)

    ; Uncomment the following lines to lift Z after probing
    ;G91 ; relative positioning
    ;G1 S2 Z5 F100 ; lift Z relative to current position
    ;G90 ; absolute positioning

    The offset of the probe is 1.0 mm

    ; Configuration file for Duet WiFi (firmware version 1.21)
    ; executed by the firmware on start-up
    ;
    ; generated by RepRapFirmware Configuration Tool v2 on Sat Mar 23 2019 15:12:34 GMT+0100 (Mitteleuropäische Normalzeit)

    ; General preferences
    G90 ; Send absolute coordinates...
    M83 ; ...but relative extruder moves

    M550 P"Ender-5 Duet" ; Set machine name

    ; Network
    M552 S1 ; Enable network

    ;*** Access point is configured manually via M587
    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 S0 ; 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 Z400.00 E840.00 ; Set steps per mm
    M566 X900.00 Y900.00 Z12.00 E120.00 ; Set maximum instantaneous speed changes (mm/min)
    M203 X6000.00 Y6000.00 Z500.00 E1200.00 ; Set maximum speeds (mm/min)
    M201 X500.00 Y500.00 Z20.00 E250.00 ; Set accelerations (mm/s^2)
    M906 X1000.00 Y1000.00 Z1000.00 E1200.00 I30 ; Set motor currents (mA) and motor idle factor in per cent
    M84 S30 ; Set idle timeout

    ; Axis Limits
    M208 X0 Y0 Z0 S1 ; Set axis minima
    M208 X225 Y200 Z205 S0 ; Set axis maxima

    ; Endstops
    M574 X1 Y1 Z1 S1 ; Set active low and disabled endstops

    ; Z-Probe
    M307 H3 A-1 C-1 D-1 ; Disable heater on PWM channel for BLTouch
    M558 P9 H10 F300 T6000 ; Set Z probe type to bltouch and the dive height + speeds
    G31 P500 X-42 Y0 Z1.00 ; Set Z probe trigger value, offset and trigger height
    M557 X15:175 Y15:185 S30 ; Define mesh grid

    ; Heaters
    M305 P0 T100000 B4138 R4700 ; Set thermistor + ADC parameters for heater 0
    M143 H0 S120 ; Set temperature limit for heater 0 to 120C
    M305 P1 T100000 B4138 R4700 ; Set thermistor + ADC parameters for heater 1
    M143 H1 S280 ; Set temperature limit for heater 1 to 280C

    ; Fans
    M106 P0 S0.3 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

    ; 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 are not configured

    0_1555432215972_830d3281-17c6-4910-adc2-b5334c405018-grafik.png



  • Why not just home Z with the BLTouch to begin with?


 

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