Hidden Z-offset Duet3

FrankV

I saw a post G30Auto-Tilt creates hidden Z-offset-Duet 3-3.0RC2, DSF1.2 there is sepose a hidden offset. The solution at the end is another probe. I experience the same at the moment. I callibrate Z-probe. Do a meshbed level. Home my Z-axis en put it to zero and my nozzle is not at bed level.
In my height map strangly the probe is at 100 - 100 not giving zero what to expect is because I leveled there and did an G92 Z0 and a G30 S-1 and put the offset in my config.g. and rebooted.
Is the issue mentioned in previous topic being solved, am I doing something wrong?

; Configuration file for Duet 3 Mini 5+ (firmware version 3.3)
; executed by the firmware on start-up
;
; generated by RepRapFirmware Configuration Tool v3.3.10 on Wed Dec 01 2021 11:48:08 GMT+0100 (Midden-Europese standaardtijd)

; General preferences
M80                                                ; Turns on the ATX power supply
G90                                                ; send absolute coordinates...
M83                                                ; ...but relative extruder moves
M550 P"SapphireS"                                  ; 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 P0.3 S0                                       ; physical drive 0.3 goes backwards
M569 P0.2 S0                                       ; physical drive 0.2 goes backwards
M569 P0.0 S0                                       ; physical drive 0.0 goes backwards
M569 P0.1 S0                                       ; physical drive 0.1 goes backwards
M584 X0.3 Y0.2 Z0.0 E0.1                           ; set drive mapping
M350 X16 Y16 Z16 E16 I1                            ; configure microstepping with interpolation
M92 X80.00 Y80.00 Z1600.00 E420.00                 ; set steps per mm
M566 X900.00 Y900.00 Z60.00 E2000.00               ; set maximum instantaneous speed changes (mm/min)
M203 X6000.00 Y6000.00 Z600.00 E6000.00            ; set maximum speeds (mm/min)
M201 X500.00 Y500.00 Z200.00 E3000.00              ; set accelerations (mm/s^2)
M906 X1500 Y1500 Z1500 E1200 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 X204 Y210 Z228 S0                             ; set axis maxima

; Endstops
M574 X1 S1 P"!io2.in"                              ; configure switch-type (e.g. microswitch) endstop for low end on X via pin !io2.in
M574 Y2 S1 P"!io1.in"                              ; configure switch-type (e.g. microswitch) endstop for high end on Y via pin !io1.in
M574 Z1 S2                                         ; configure Z-probe endstop for low end on Z

; Z-Probe
M558 P5 R0.4 C"io3.in" H5 F1200 T6000               ; set Z probe type to effector and the dive height + speeds
;G31 P500 X0 Y-24 Z2.22                              ; set Z probe trigger value, offset and trigger height
G31 P500 X0 Y-24 Z1.8                               ; set Z probe trigger value, offset and trigger height
M557 X4:200 Y0:175 S25                              ; define mesh grid
G29 S1                                              ; load mesh bed leveling

;Diasble pinda
;M308 S2 P"temp2" A"Pinda" Y"thermistor" T100000 B3950 ; temperature of PINDA2

; Heaters
M308 S0 P"temp0" Y"thermistor" T100000 B4138       ; configure sensor 0 as thermistor on pin temp0
M950 H0 C"out0" T0                                 ; create bed heater output on out0 and map it to sensor 0
M307 H0 B0 S1.00                                   ; disable 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"temp1" Y"thermistor" T100000 B4138       ; configure sensor 1 as thermistor on pin temp1
M950 H1 C"out1" T1                                 ; create nozzle heater output on out1 and map it to sensor 1
M307 H1 B0 S1.00                                   ; disable bang-bang mode for heater  and set PWM limit
M143 H1 S280                                       ; set temperature limit for heater 1 to 280C
M307 H0 B0 R0.364 C295.6 D3.88 S1.00 V24.0         ; set PID Bed

; Fans
M950 F0 C"out5" Q500                               ; create fan 0 on pin out5 and set its frequency
M106 P0 S1 H1 T45                                  ; set fan 0 value. Thermostatic control is turned on
M950 F1 C"out6" Q500                               ; create fan 1 on pin out6 and set its frequency
M106 P1 S0 H-1                                     ; set fan 1 value. Thermostatic control is turned off

; Tools
M563 P0 D0 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

; Custom settings are not defined

; Miscellaneous
M911 S10 R11 P"M913 X0 Y0 G91 M83 G1 Z3 E-5 F1000" ; set voltage thresholds and actions to run on power loss

fcwilt

@frankv

I would like to help but I am having trouble following your post.

Let's start with just two items:

"Do a meshbed level"
"Home my Z-axis and put it to zero"

For each one what exactly are you doing?

You can use the </> tag to copy-and-past the code here for easy viewing.

Thanks.

Frederick

FrankV

@fcwilt

Thank you. I follow exact https://duet3d.dozuki.com/Wiki/Test_and_calibrate_the_Z_probe.

Enter the value in config.g. Do a reset. After reset home-all and test if all is ok with a paper test. All is ok.

After that I do meshbed level G29.

Home all again and at that moment I do have wrong values for Z. The nozzle is not touching the bed and my prints are going wrong.

fcwilt

@frankv

Please post your homeall.g code using the </> icon.

Please post a screen shot of your height map using the "upload image" icon

Thanks.

Frederick

FrankV

@fcwilt

; homeall.g
; called to home all axes
;
; generated by RepRapFirmware Configuration Tool v3.3.10 on Sun Nov 28 2021 20:42:31 GMT+0100 (Midden-Europese standaardtijd)
G91                    ; relative positioning
G1 H2 Z5 F6000         ; lift Z relative to current position
G1 H1 X-209 Y223 F1800 ; move quickly to X or Y endstop and stop there (first pass)
G1 H1 X-209            ; home X axis
G1 H1 Y223             ; home Y axis
G1 X5 Y-5 F6000        ; go back a few mm
G1 H1 X-209 F360       ; move slowly to X axis endstop once more (second pass)
G1 H1 Y223             ; then move slowly to Y axis endstop
G90                    ; absolute positioning
G1 X100 Y100 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

FrankV

Hi Frederique,

Thanks for looking into it.

Frank

FrankV

@fcwilt

Dear Frederick,

I think I found the problem. I did several test's.
At room temperature my z-offset = 0.95
My bed at 90 degrees celcius my z-offset = 1.27
My hotend at 250 degrees celcius my z-offset = 1.87

The pinda is just behind the hotend so the temperature is influencing the pinda probe up to 1 mm.

The other thing is even at room temp when I do automatic bed level the same point is getting a compensation of -0.1.

So my conclusion is. Temperature is influencing the probe to much. I tried the temp sensor of the pinda to get corrected for temp. But I don't find how it's calculated and how that algorithm works and if it solves my problem. I ordered a super pinda. Hope it solves the temp issue. I got a bl touch laying around so maybe give that one a try. I never imagine temp is influencing almost 1 mm.

fcwilt

@frankv

Interesting about the change in readings.

I use an inductive probe on one of my printers but I never thought to check for temperature sensitivity.

I did mount the hotend cooling fan so it sucks air past the inductive probe on the way to the hotend. Perhaps that is why I never encountered any problems.

But I also create the height map with bed/hotend at working temps.

Frederick

FrankV

@fcwilt

Frederick i think i add these lines. I have to check the C factor with the probe temp sensor. First without compenation and then with compensation and see what the result is.

;M308 S2 P"temp2" A"Pinda" Y"thermistor" T100000 B3950 ; temperature of PINDA2
;G31 P500 X0 Y-24 Z0.95 S21 H2 C0.02 ; C' (temperature coefficient of Z parameter in mm/°C, default zero

FrankV

@fcwilt

Frederick,

This is the graph produced by the Z- probe thermistor and my measurements of the Z offset by G30 S-1 at specific temperatures. So 50 degrees is 1mm extra z-offset this makes the C in the G31 temperature coefficient of Z parameter in mm/°C 0.02 although it's not lineair.

I am adding in config.g:
M308 S2 P"temp2" A"Pinda" Y"thermistor" T100000 B3950 ; temperature of PINDA2
G31 P500 X0 Y-24 Z0.95 S21 H2 C0.02 ; C' (temperature coefficient of Z parameter in mm/°C, default zero

Tried this but it's not leading to higher the trigger distance when the probe is 50 degrees hotter. So this is not working. My superpinda just arrived wich seems to be temperature resistent. Let's try because this is not leading to consistent z-offset in my case.

I changed in config.g the C to T because of Firmware 3.3 in my machine and now it's working:
M308 S2 P"temp2" A"Pinda" Y"thermistor" T100000 B3950 ; temperature of PINDA2
G31 P500 X0 Y-24 Z0.95 S21 H2 T0.02 ; T' (temperature coefficient of Z parameter in mm/°C, default zero

Still going to test the superpinda, see if it works better without compensation.

fcwilt

@frankv

Interesting.

Glad to hear you got the settings sorted for the probe.

Frederick

FrankV

@fcwilt Frederick thanks for your help.

fcwilt

@frankv said in Hidden Z-offset Duet3:

@fcwilt Frederick thanks for your help.

Always glad to do what I can.

Frederick

FrankV

A little status update from my part. Today I installed the superPinda probe. This probe has no need for temperature compensation like the Pinda V2. It works great and keeps logic more simple to calculate the Z-offsets. Also there is less difference when I probe again and again. So I can advise this superPinda also sold as upgrade from Prusa. You can buy it better from them because it's much cheaper as the orginal manufacturer price from Pepperl-fuchs (superPINDA)
Inductive sensor NBN2,5-8GM35-E1L-Y. I attached the datasheet if anyone is interested. It's rated till 80degrees celcius. I heated it till 110 with no deviation.

Brown is 5V
Blue is GND
Black is signal

An easy drop in to one of the endstop io's when you remove the wings from the connector.

SuperPrinda-datasheet_70134664_eng.pdf

In noticed even deviation of 1.04 mm at 80 degrees celcius.

fcwilt

@frankv

You might find this site of interest. They have a large selection of good quality inductive sensors. For example they list 154 8mm diameter devices.

If you ever need a sensor with a greater sensing distance or faster switching speed you can likely find one to suit your needs.

Inductive Sensors

Frederick

FrankV

@fcwilt Frederick, thank you great site.