IR Probe issue



  • Hi all,

    I am currently configuring my IR probe and cant seem to get it to home my Z axis properly..

    The edge of the board it just over 1mm higher than the nozzle and I get 4 flashes when I switch the machine on. I am also using blue tape on the bed under the sensor. I get a reading of 0 with nothing under the sensor, 4.65 with a piece of paper near the sensor and 538 when the led lights up.

    I send M558 P1 followed by G31 P500 Z1.0, then lower the head to grab a piece of paper and send Z92 Z0 to the printer, raise the head by 5mm and then send G30 S-1 which gives me a head height of 2.84mm. I enter the value into my G31 line in the config.g and cycle the power but the head always homes to 2.84 and obviously this is over a couple of mm too high. Am I missing something as the way I see it the firmware knows I want to home at 0 hence the g92 command and it knows the trigger height - what am I missing to make it get to 0 once the sensor triggers?

    Thanks in advance!

    ; General preferences
    M111 S0 ; Debugging off
    G21 ; Work in millimetres
    G90 ; Send absolute coordinates…
    M83 ; ...but relative extruder moves
    M555 P2 ; Set firmware compatibility to look like Marlin

    M667 S1 ; Select CoreXY mode
    M208 X0 Y0 Z0 S1 ; Set axis minima
    M208 X290 Y100 Z100 S0 ; Set axis maxima

    ; Endstops
    M574 X1 Y2 Z0 S0 ; Define active low and unused microswitches
    M558 P1 X0 Y0 Z1 H5 F200 T5000 ; Set Z probe type to analog, the axes for which it is used and the probe + travel speeds
    G31 P500 X0 Y0 Z2.84 ; Set Z probe trigger value, offset and trigger height
    M557 X15:85 Y15:85 S20 ; Define mesh grid

    ; Drives
    M569 P0 S0 ; Drive 0 goes backwards
    M569 P1 S1 ; Drive 1 goes forwards
    M569 P2 S0 ; Drive 2 goes backwards
    M569 P3 S1 ; Drive 3 goes forwards
    M350 X16 Y16 Z16 E16 I1 ; Configure microstepping without interpolation
    M92 X100 Y100 Z400 E418.5 ; Set steps per mm
    M566 X900 Y900 Z12 E120 ; Set maximum instantaneous speed changes (mm/min)
    M203 X5000 Y5000 Z180 E1200 ; Set maximum speeds (mm/min)
    M201 X2000 Y3000 Z250 E250 ; Set accelerations (mm/s^2)
    M906 X800 Y800 Z800 E800 I60; Set motor currents (mA) and motor idle factor in per cent
    M84 S60 ; Set idle timeout

    ; Heaters
    M143 S290 ; Set maximum nozzle heater temperature to 250C
    M307 H0 A410.7 C190.6 D5.0 B0 ; Bed heater autotune results
    M307 H1 A516.2 C193.2 D5.5 B0 ; Nozzle heater autotune results
    M305 P0 T100000 B3950 C0 R4700 ; Set thermistor + ADC parameters for heater 0 (Bed)
    M305 P1 T100000 B4725 C7.060000e-8 R4700 ; Set thermistor + ADC parameters for heater 1 (Nozzle)

    ; 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

    ; Network
    M550 PCoreXY ; Set machine name
    M552 P0.0.0.0 S1 ; Enable network and acquire dynamic address via DHCP

    ; Fans
    M106 P0 S1 I0 F500 H1 T40 ; Set fan 0 value, PWM signal inversion and frequency. Thermostatic control is turned on
    M106 P1 S0 I0 F500 H-1 ; Set fan 1 value, PWM signal inversion and frequency. Thermostatic control is turned off
    M106 P2 S0 I0 F500 H-1 ; Set fan 2 value, PWM signal inversion and frequency. Thermostatic control is turned off

    ; Custom settings are not configured

    ; Miscellaneous
    T0 ; Select first tool



  • The mini IR sensor on my printer always stops Z at the triggered height when homing and running an auto level. The G31 Z offset is the amount past that triggered height that Z will move when printing. Have you tried printing anything?


  • administrators

    The purpose of homing is to establish a known position, which does not need to be zero. Your printer is homing correctly. If you want it to end up at Z=0 after homing, you can add command G1 Z0 to the end of homeall.g and homez.g. But it's not necessary.



  • Ahhh I get it now!! So the trigger height is just a reference position and the z0 command will be given to the printer when printing by the slicers g code?



  • @Prawnabie:

    Ahhh I get it now!! So the trigger height is just a reference position and the z0 command will be given to the printer when printing by the slicers g code?

    Mostly correct but actually the first Z move will be to the Z position that corresponds to your first layer height is - i.e something like G1 Z0.3.


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