After Z probing, print head smashing into bed

[Adam_Sw3]

Good Evening all, as the title states my print head smashes into the bed. I have checked my leadscrew pitch all correct etc. I have levelled it using true bed levelling etc its all flat and the Z probe offset is accurate. The only problem is, is that when I start a print, it seems to disregard all this effort and just smash the head straight into the bed! Any help?

Config Below:

.; Configuration file for Duet WiFi (firmware version 3.3)
; executed by the firmware on start-up
;
; generated by RepRapFirmware Configuration Tool v3.3.14 on Sat Oct 29 2022 18:08:10 GMT+0100 (British Summer Time)

; General preferences
G90                                            ; send absolute coordinates...
M83                                            ; ...but relative extruder moves
M550 P"Printer"                                 ; set printer name
M669 K1                                        ; select CoreXY mode

; Network
M552 S1                                        ; enable network
M586 P0 S1                                     ; enable HTTP
M586 P1 S0                                     ; disable FTP
M586 P2 S0                                     ; disable Telnet

; Drives
M569 P0 S0                                     ; physical drive 0 goes forwards X axis
M569 P1 S0                                     ; physical drive 1 goes forwards Y Axis
M569 P2 S0                                     ; physical drive 2 goes forwards 2 x Z axis
M569 P3 S1                                     ; physical drive 3 goes forwards Extruder 0
M569 P4 S0                                     ; physical drive 4 goes forwards - Extruder 1
;M569 P5 S0                                     ; physical drive 5 goes forwards - Extruder 2
;M569 P6 S0                                     ; physical drive 6 goes forwards - Extruder 3
M569 P7 S1                                     ; physical drive 9 goes forwards - 3rd Z motor
M569 P6 S1                                     ; physical drive 2 goes forwards 2nd Z motor


M584 X0 Y1 Z2:5:6 E3:4                               ; set drive mapping
M671 X290:0:470 Y10:470:470 S0.5 ; position of leadscrew/bed pivot point at front left, rear middle and front right
M350 X16 Y16 Z16 E16 I1                        ; configure microstepping with interpolation
M92 X80.00 Y80.00 Z1066.67 E446.8              ; set steps per mm
M566 X900.00 Y900.00 Z60.00 E120.00            ; set maximum instantaneous speed changes (mm/min)
M203 X6000.00 Y6000.00 Z180.00 E1200.00        ; set maximum speeds (mm/min)
M201 X500.00 Y500.00 Z20.00 E250.00            ; set accelerations (mm/s^2)
M906 X1500 Y1500 Z1500 E1000 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 X470 Y470 Z500 S0                         ; set axis maxima

; Endstops
M574 X1 S1 P"!xstop"                            ; configure switch-type (e.g. microswitch) endstop for low end on X via pin xstop
M574 Y1 S1 P"!ystop"                            ; configure switch-type (e.g. microswitch) endstop for low end on Y via pin ystop
M574 Z1 S2                                     ; configure Z-probe endstop for low end on Z

; Z-Probe
M558 P1 C"!zprobe.in" H10 F240 T6000            ; set Z probe type to unmodulated and the dive height + speeds
G31 P500 X35 Y0 Z2.47                          ; set Z probe trigger value, offset and trigger height
M557 X15:525 Y10:400 S50                       ; define mesh grid

; Heaters
M308 S0 P"bedtemp" Y"thermistor" T100000 B4138 ; configure sensor 0 as thermistor on pin bedtemp
M950 H0 C"bedheat" T0                          ; create bed heater output on bedheat and map it to sensor 0
M307 H0 R0.310 K0.291:0.000 D1.41 E1.35 S1.00 B0                              ; enable bang-bang mode for the bed heater and set PWM limit
M140 H0                                        ; map heated bed to heater 0
M143 H0 S120                                   ; set temperature limit for heater 0 to 120C
M308 S1 P"e0temp" Y"thermistor" T100000 B4138  ; configure sensor 1 as thermistor on pin e0temp
M950 H1 C"e0heat" T1                           ; create nozzle heater output on e0heat and map it to sensor 1
M307 H1 B0 S1.00                               ; disable bang-bang mode for heater  and set PWM limit
M143 H1 S300                                   ; set temperature limit for heater 1 to 300C

; Fans
M950 F0 C"fan0" Q500                           ; create fan 0 on pin fan0 and set its frequency
M106 P0 S0 H-1                                 ; set fan 0 value. Thermostatic control is turned off
M950 F1 C"fan1" Q500                           ; create fan 1 on pin fan1 and set its frequency
M106 P1 S1 H1 T45                              ; set fan 1 value. Thermostatic control is turned on

; Tools
M563 P0 S"MATERIAL 1" D3 H1 F0                 ; 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
M563 P1 S"MATERIAL 2" D4 H1 F0                 ; define tool 1
G10 P1 X0 Y0 Z0                                ; set tool 1 axis offsets
G10 P1 R0 S0                                   ; set initial tool 1 active and standby temperatures to 0C
M563 P2 S"MATERIAL 3" D5 H1 F0                 ; define tool 2
G10 P2 X0 Y0 Z0                                ; set tool 2 axis offsets
G10 P2 R0 S0                                   ; set initial tool 2 active and standby temperatures to 0C
M563 P3 S"MATERIAL 3" D5 H1 F0                 ; define tool 2
G10 P3 X0 Y0 Z0                                ; set tool 2 axis offsets
G10 P3 R0 S0                                   ; set initial tool 2 active and standby temperatures to 0C

; Custom settings are not defined

Is my G31 P value correct?

Heres a sample of my start code exported out of cura.

;FLAVOR:RepRap
;TIME:958
;Filament used: 1.06216m
;Layer height: 0.2
;MINX:271
;MINY:208
;MINZ:0.3
;MAXX:299
;MAXY:236
;MAXZ:19.9
;Generated with Cura_SteamEngine 5.4.0
T0
M190 S50
M104 S250
M109 S250
M82 ;absolute extrusion mode
G28 ;Home
G1 Z15.0 F6000 ;Move the platform down 15mm
;Prime the extruder
G92 E0
G1 F200 E3
G92 E0
M83 ;relative extrusion mode
G1 F1500 E-6.5
;LAYER_COUNT:99
;LAYER:0
M107
G0 F3600 X271.858 Y209.549 Z0.3
;TYPE:SKIRT
G1 F1500 E6.5
G1 F1800 X272.284 Y209.084 E0.03146
G1 X272.779 Y208.691 E0.03153
G1 X273.325 Y208.382 E0.0313
G1 X273.857 Y208.18 E0.02839
G1 X274.516 Y208.04 E0.03361
G1 X274.961 Y208.003 E0.02228
G1 X294.351 Y208 E0.96737
G1 X295.083 Y208.012 E0.03652

Any help would be greatly appreciated, thank you.

[fcwilt]

@Adam_Sw3

As a test:

• move the probe to the center of the bed
• execute G30
• execute G30 S-1

The G30 S-1 should report the same value as used in G31 for your Z probe trigger value.

Let us know the result.

Frederick

[gloomyandy]

@Adam_Sw3 It looks like you have multiple extruders. What sort of printer is this do you have a toolchanger of some sort? Posting a picture of the printer might make it easier for folks to help you.

With tool 0 selected, if you manually move the print head so that the tool 0 nozzle just touches the bed, what Z position is displayed in DWC?

[Adam_Sw3]

@fcwilt Hi There, yes it reports the result of 2.47. I have done this numerous times and somehow its still not working...

[Adam_Sw3]

@gloomyandy That is correct, its a custom built machine with its own material holder on the top. All of these materials go through one nozzle (switching hotend)

[gloomyandy]

@Adam_Sw3 What was the result of positioning the tool so that the nozzle is just touching the bed? What is the Z reading when in that position?

[fcwilt]

@Adam_Sw3 said in After Z probing, print head smashing into bed:

@fcwilt Hi There, yes it reports the result of 2.47. I have done this numerous times and somehow its still not working...

Thanks for checking it.

The code at the start of the print file looks correct.

One of the first things it does is a G28 to home all.

I assume homing works fine when done from the Dashboard?

Frederick

[Adam_Sw3]

@fcwilt Hi frederick, thanks for confirming, yes the homing works fine etc.

[Adam_Sw3]

@gloomyandy ermmm, you may have got me onto this issue, its reporting 7.2mm.

[fcwilt]

@Adam_Sw3 said in After Z probing, print head smashing into bed:

you may have got me onto this issue, its reporting 7.2mm.

Do you have some code that is setting the Z offset of the tool?

Frederick

[Adam_Sw3]

@fcwilt Hi, i am using the duet reccomended way -> https://docs.duet3d.com/User_manual/Connecting_hardware/Z_probe_testing

The problem, i am having it seems, is that when I centre the nozzle and place it onto the bed after following this guide, it reports 4mm even though its technically zero (since the nozzle is touching)? I dont really understand whats going on here.

[Adam_Sw3]

@fcwilt It looks like the Z probe is 3.91mm away but the nozzle is touching the bed. I dont really understand...

[fcwilt]

@Adam_Sw3 said in After Z probing, print head smashing into bed:

@fcwilt It looks like the Z probe is 3.91mm away but the nozzle is touching the bed. I dont really understand...

Do you have config-override.g file? If so did you check it's contents for something affecting the settings of the probe or tool?

What sort of Z probe are you using?

After setting the Z=0 Datum using G30 you should be able to move the nozzle so it is just touching the bed and the Z position should be shown as 0 or close to it.

Does it work that way?

Frederick

[Adam_Sw3]

@fcwilt I do but it is empty. I am using a inductance sensor. I have done that G30 command proccess. But turned out the problem was that the bed wasnt level, anyways I used true bed levelling that sorted this. I repeated the proccess again, yet when the nozzle is touching the build plate it reads a z position of 1.4mm. Which i dont really understand?

[Adam_Sw3]

@fcwilt Would increasing my Z offset bring it further away from the bed and then from there, i could baby step it down onto the bed? Or would it be the inverse (decreasing Z offset)

[Phaedrux]

Can you share your homing files and bed.g and any other macros you're using for leveling?

What firmware version?

@Adam_Sw3 said in After Z probing, print head smashing into bed:

M92 X80.00 Y80.00 Z1066.67

How did you determine those steps per mm for Z? It seems a strange value.

For a leadscrew z axis the formula for steps per mm is as follows.

Z_steps_per_mm = (motor_steps_per_rev * driver_microstep) / screw_lead

[Adam_Sw3]

@Phaedrux hello Phaedrux! yes certainly, i will supply these in the morning (GMT 08:00) i will share these. I got these z steps per mm using the prusa calculator. I am using this Lead screw https://uk.rs-online.com/web/p/lead-screws/8625281?gb=s i also checked with verniers ie down 25mm etc.

Thank you.

[fcwilt]

@Adam_Sw3 said in After Z probing, print head smashing into bed:

@fcwilt Would increasing my Z offset bring it further away from the bed and then from there, i could baby step it down onto the bed? Or would it be the inverse (decreasing Z offset)

That would be putting a bandage on the symptoms and hiding the real problem.

Hang in there - we will sort it.

Frederick

[Adam_Sw3]

@Phaedrux

Hi Phaedrux, my bed.g is here

; bed.g
; called to perform automatic bed compensation via G32
;
; generated by RepRapFirmware Configuration Tool v3.3.14 on Sat Oct 29 2022 18:08:10 GMT+0100 (British Summer Time)
G28 ; home

G30 P0 X0 Y440 Z-99999 ; probe near a leadscrew
G30 P1 X570 Y440 Z-99999 ; probe near a leadscrew
G30 P2 X290 Y10 Z-99999 S3 ; probe near a leadscrew and calibrate 3 motors




;M561 ; clear any bed transform
;G29  ; probe the bed and enable compensation

Home all

; homeall.g
; called to home all axes
;
; generated by RepRapFirmware Configuration Tool v3.3.14 on Sat Oct 29 2022 18:08:10 GMT+0100 (British Summer Time)
G91                     ; relative positioning
G1 H2 Z5 F6000          ; lift Z relative to current position
G1 H1 X-555 Y-415 F1800 ; move quickly to X or Y endstop and stop there (first pass)
G1 H1 X-555             ; home X axis
G1 H1 Y-415             ; home Y axis
G1 X5 Y5 F6000          ; go back a few mm
G1 H1 X-555 F360        ; move slowly to X axis endstop once more (second pass)
G1 H1 Y-415             ; then move slowly to Y axis endstop
G90                     ; absolute positioning
G1 X-20 Y10 F6000       ; go to first bed probe point and home Z
G30                     ; home Z by probing the bed

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

Home X

; homex.g
; called to home the X axis
;
; generated by RepRapFirmware Configuration Tool v3.3.14 on Sat Oct 29 2022 18:08:10 GMT+0100 (British Summer Time)
G91               ; relative positioning
G1 H2 Z5 F6000    ; lift Z relative to current position
G1 H1 X-555 F1800 ; move quickly to X axis endstop and stop there (first pass)
G1 X5 F6000       ; go back a few mm
G1 H1 X-555 F360  ; move slowly to X axis endstop once more (second pass)
G1 H2 Z-5 F6000   ; lower Z again
G90               ; absolute positioning

Home Y

; homey.g
; called to home the Y axis
;
; generated by RepRapFirmware Configuration Tool v3.3.14 on Sat Oct 29 2022 18:08:10 GMT+0100 (British Summer Time)
G91               ; relative positioning
G1 H2 Z5 F6000    ; lift Z relative to current position
G1 H1 Y-415 F1800 ; move quickly to Y axis endstop and stop there (first pass)
G1 Y5 F6000       ; go back a few mm
G1 H1 Y-415 F360  ; move slowly to Y axis endstop once more (second pass)
G1 H2 Z-5 F6000   ; lower Z again
G90               ; absolute positioning

Home Z

; homez.g
; called to home the Z axis
;
; generated by RepRapFirmware Configuration Tool v3.3.14 on Sat Oct 29 2022 18:08:10 GMT+0100 (British Summer Time)
G91               ; relative positioning
G1 H2 Z5 F6000    ; lift Z relative to current position
G90               ; absolute positioning
G1 X-20 Y10 F6000 ; go to first probe point
G30               ; home Z by probing the bed

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

Current firmware is
FIRMWARE_NAME: RepRapFirmware for Duet 2 WiFi/Ethernet FIRMWARE_VERSION: 3.4.4 ELECTRONICS: Duet WiFi 1.02 or later + DueX5 FIRMWARE_DATE: 2022-10-20 16:17:41

[Adam_Sw3]

@fcwilt Thanks Frederick! Its people like you that really go under appreciated in these forums, thanks for your help. I have replied to phaedrux below so we shall see what he says.