DC42's mini probe offset



  • Hi,
    I have a couple of questions.
    I have fitted the mini probe to my coreXY printer with duetwifi electronics and had to set the mode to "P3" for it to work but the instructions say it should be mode 1.
    The Z-Probe is displaying 80 and jumps to 515 at the trigger height, also it only flashes twice on power up

    I have looked at using mesh bed compensation and the following instructions:-

    Make sure that your Z probe is correctly configured and working. This includes the trigger height and the X and Y offsets of the probe relative to the nozzle. Refer to the M558 and G31 commands in the GCodes page of the reprap.org wiki at http://reprap.org/wiki/G-code.

    Having looked at the references I can not find any mention of setting XY probe offset from the nozzle. Do I need this on a coreXY printer?



  • If it only flashes twice its in digital mode not analogue so it will be slightly less sensitive.

    I have this in my config.g
    M558 P1 X0 Y0 Z0 ; Z probe is an IR probe and is not used for homing any axes
    G31 X-13 Y13 Z2.7 P535 ; Set the zprobe height and threshold (put your own values here)

    My probe is in front of the nozzle by 13mm and to the right of the nozzle by 13mm.

    As for whether you need an offset entered, I would say yes, if you want to use grid levelling, since the offset at each position probed has to be translated into an offset for the nozzle when printing. If you are not using grid levelling and your probe is quite close to the nozzle you can autolevel without, but you might get probing outside of the bed, the firmware uses the offset to ensure the probe stays within the bed.



  • Thank you DjDemonD
    How do I set the probe to be analogue?
    Thanks I see the offset goes in G31
    I'm assuming that I would put M558 P1 X0 Y0 Z1 if I want the homing to be done by the probe.



  • @appjaws:

    Thank you DjDemonD
    How do I set the probe to be analogue?
    Thanks I see the offset goes in G31
    I'm assuming that I would put M558 P1 X0 Y0 Z1 if I want the homing to be done by the probe.

    Yes thats my understanding that Z1 would enable z endstop by probe.

    As for analogue I didn't have to set anything. I think using M558 P1 sets analogue mode on that pin and the mini IR detects this and flashes 4 times on startup.



  • I just can't get it to work. This is my entry in config

    M558 P1 X0 Y0 Z1
    G31 X-20 Y10 Z0.99 P500

    I have the wires connected as follows:-
    Duetwifi probe connector, pin nearest the ribbon connector for the duex5, I have connected to probe vcc
    the next pin, moving away from the ribbon connector, is not connected
    the third pin is connected to the probe grd
    and the fourth pin is connected to the probe out

    Can you confirm that that is correct please. If it is then I do have a problem

    With the above connections, when power on I get 1 flash immediately and the Z probe reading is 1000, it stays around there regardless of height from the bed. If I home Z the bed moves down instead of up!!!

    If I reverse the vcc and out connections on the mini board, I get 4 flashes at power on (correct)and manually I can move the bed until the red light comes on but if I home Z, the bed does not move at all because it is homed as soon as the button is clicked.
    I can manually home Z but clicking the web interface home Z button (G28 Z) moves the bed in the wrong direction and then thi Z0 is set.

    I am now totally confused but feel I'm nearly there, it's just the home Z issue now.



  • do you mind tossing up your config and homing files? so that i can compare them to mine? i've had the ir probe working in the past and currently home using a bltouch so for homing and probing purposes i should be able to get you going



  • Config
    ; CoreXY config file for Duet firmware on appjawsCoreXY

    M111 S0 ; Debug off
    M550 PappjawsCoreXY ; Machine name (can be anything you like)
    M551 Appjawsxy% ; Machine password (used for FTP connections)
    M540 P0xBE:0xEF:0xDE:0xAD:0xFE:0xED ; MAC Address
    M552 S1 ; Enable WiFi
    M555 P2 ; Set output to look like Marlin

    ; Machine configuration
    M569 P0 S0 ; Drive 0 goes forwards (change to S0 to reverse it)
    M569 P1 S0 ; Drive 1 goes forwards
    M569 P2 S0 ; Drive 2 goes backwards (Z)
    M569 P3 S1 ; Drive 3 goes forwards (extruder1)
    M569 P4 S1 ; Drive 4 goes forwards (extruder2)
    M569 P5 S1 ; Drive 4 goes forwards (extruder3)
    M574 X1 Y2 Z1 S1 ; set endstop configuration (Y endstop only, at high end, active high)
    M667 S1 ; set CoreXY mode
    M350 X16 Y16 E16 I1 ; Set 16x microstepping with interpolation
    M92 X80.0 Y80.0 Z3200 ; Set axis steps/mm
    M906 X950 Y950 Z950 E950 ; Set motor currents (mA)
    M201 X700 Y700 Z200 E2000 ; Accelerations (mm/s^2)
    M203 X15000 Y15000 Z200 E4000 ; Maximum speeds (mm/min)
    M566 X800 Y800 Z30 E100 ; Maximum jerk speeds mm/minute
    M208 X290 Y194 Z250 ; set axis maxima (adjust to suit your machine)
    M208 X5 Y5 Z0 S1 ; set axis minima (adjust to make X=0 and Y=0 the edges of the bed)
    G21 ; Work in millimetres
    G90 ; Send absolute coordinates…
    M83 ; relative extruder moves
    ;M572 D0 S0.2 ; pressure advance Dnnn Extruder num,Snnn advance amount(sec) 0.1 - 0.2
    ;M556 S78 X0 Y0 Z0 ; Axis compensation here
    M501 ;load saved values
    T0 ; select first hot end

    ; Z probe
    M558 P3 X0 Y0 Z1 ; Analog Z probe, also used for homing the Z axis
    G31 X-20 Y10 Z0.99 P500 ; Set the probe height and threshold;

    ; Thermistors and heaters
    ;*** You can use S and B parameters to define the parameters of the thermistors you are using
    ;M305 P0 R4700 B3950 ; H and/or L values to set the bed thermistor ADC correction
    ;M305 P1 R4700 B4719 7.08e-8 ; H and/or L values to set the nozzle 1 thermistor ADC correction
    ;M301 H0 P10 I0.20 D50 T0.50 S1.0 ; PID settings for bed heater
    ;M301 H1 P10 I0.20 D50 T0.50 S1.0 ; PID settings for extruder 0
    M307 H0 A112.6 C519.5 D11 B0 ; Auto tune PID for bed heater
    M307 H1 A552.9 C237.9 D6.9 B0 ; Auto tune PID for extruder 0
    ;M570 S120 ; Increase to allow extra heating time if needed

    ; Tool definition********** Single nozzle settings **********
    M563 P0 D0 H1 ; Define tool 0
    G10 P0 S0 R0 ; Set tool 0 operating and standby temperatures
    ;M92 E175 ; Set extruder steps per mm (single nozzle D-Bot extruder)
    M92 E430 ; Set extruder steps per mm (single nozzle ormerod extruder)

    ; ********** Diamond nozzle settings **********
    ;M563 P0 D0:1:2 H1 ; Define tool 0 extruder 0
    ;M563 P1 D0:1:2 H1 ; Define tool 1 extruder 1
    ;M563 P2 D0:1:2 H1 ; Define tool 2 extruder 2
    ;M567 P0 E1.0:0.0:0.0 ; single colour - extruder 0
    ;M567 P1 E0.0:1.0:0.0 ; single colour - extruder 1
    ;M567 P2 E0.0:0.0:1.0 ; single colour - extruder 2
    ;M92 E430:430:430 ; Set extruder steps/mm (multiple nozzles)
    ;M568 P0 S1 ; turn on mixing Tool 0
    ;M568 P1 S1 ; turn on mixing Tool 0
    ;M568 P2 S1 ; turn on mixing Tool 0
    ;M207 S5.0 F2400 ; retract all extruders

    home Z
    G91
    G1 Z-260 F150 S1
    G1 Z4 F100
    G1 Z-5 F30 S1
    G1 Z5 F150
    G90

    Thanks for any help



  • I could be misunderstanding some things, but when you want to use the probe to home the bed you should use G30

    If Z is moving the wrong way you need to change M569 P2 S0 to M569 P2 S1, on a "standard" corexy machine, positive Z has the bed lowering away from the nozzle and negative Z has it rising.

    Looking at your homeZ file, it has it going to relative mode, then the bed raising 260mm then dropping away 4, raising 5, then dropping away 5, before going back to absolute mode.

    For homing Z with a probe you should only need to move the probe to a position that has it over the bed and then use G30 to raise the bed until the probe triggers and then stops. you can of course do more than this but that's the minimum to home with a probe.

    as an example here are my homeall and homeZ.g files(modified to not use deploy and retract)

    ;homeall.g
    G91                       ; relative mode
    G1 Z4 F200       	  ; raise head 4mm to ensure it is above the Z probe trigger height
    G1 S1 X-340 Y-340 F3000   ; course home X or Y
    G1 S1 X-340               ; course home X
    G1 S1 Y-340               ; course home Y
    G1 X4 Y4 F600             ; move away from the endstops
    G1 S1 X-10                ; fine home X
    G1 S1 Y-10                ; fine home Y
    ; Z homing section follows
    G90              	  ; absolute mode
    G1 X150 Y150 F1000	  ; put head over the centre of the bed, or wherever you want to probe
    G30             	  ; lower head, stop when probe triggered and set Z to trigger height
    
    ;HomeZ.g
    
    G91                ; relative mode
    G1 Z6 F200         ; raise head 6mm to ensure it is above the Z probe trigger height
    G90                ; back to absolute mode
    G1 X150 Y150 F1000 ; put head over the centre of the bed, or wherever you want to probe
    G30                ; lower head, stop when probe triggered and set Z to trigger height
    
    


  • Thank you so much Sniffle, that was the problem, everything appears to be working fine, although I don't understand why I need to use P3 as the mode and the wiring is reversed from what is shown in the instructions.


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