Unable to home z axis

Kayjay

Just an intersting item I found in my bits and bobs box. I bought it years ago, it was poorly printed as you can see but the circuit design and construction was good. It's a filament diameter sensor to detect variances in filament thickness and as such the flow through the hotend could be adjusted. I know Marlin was adjusted to enable this to be used and I used it on my old Prusa Mendel to good use but it meant me changing from Repetier (which was far superior at the time and may still be) to Marlin. If anyone wants to make one it can be found on Thingverse.

http://www.thingiverse.com/thing:454584

Keith

Phaedrux

While we still don't know what is wrong with your probe, I had an idea to try switching to manual probing so that you can maybe at least get up and running.

In config.g change your M558 P1 to P0 for manual probing. That will mean that when it gets to the G30 part in your homeall, it should pop up a dialog box asking you to jog the Z axis to touch the nozzle. Let's see if that works.

dc42

In your config.g file you have this:

M558 P1 H5 F120 T6000                   ; set Z probe type to unmodulated and the dive height + speeds
G31 P500 X0 Y25 Z2.5                    ; set Z probe trigger value, offset and trigger height

That looks correct to me, however we can't rule out the possibility that there is a non-printing character in one of those lines that is messing things up. So please send the following commands from the console, with no extra parameters:

M558
G31 T1

and check that they report the expected values.

droftarts

@dc42 said in Unable to home z axis:

So please send the following commands from the console, with no extra parameters:
M558
G31 T1
and check that they report the expected values.

Did this today with Keith, response was correct. One odd thing was probe reading was 0 to 1000, rather than 0 to 530. I suspect a damaged probe.

Ian

Kayjay

Thanks for the responses there Ian, you saved me answering the individual posts. I have the Duet2, both daughterboards and probe/cables all packed up ready to go to the P.O. in the morning.

Kayjay

@dc42

Ian is going to check the board over for me to see if it's faulty or the probe is etc, etc.

If per chance I need a new board are you shipping yet or should I go to a dealer, say best for me woukd be E3D-Online.

Thanks
Keith

droftarts

TL/DR: Weird G30 probing behaviour? Check if you have a sys/deployprobe.g file and a probe that doesn't need deploying!

Just for posterity, I'm posting to say that this issue has finally been resolved, though the Duet does need to be reinstalled in the printer, as Keith ended up sending me his Duet, probe and probe wiring to work out what was wrong!

The main problem was that a Mini Kossel example sys folder had been used as a starting point. The Mini Kossel featured a probe that was deployed by moving the effector around in X, Y and Z in order to 'twang' one of the belts and deploy the probe! The Kossel setup had then been overwritten with a Cartesian setup featuring an IR probe. But this left some files behind, including deployprobe.g, retractprobe.g and homedelta.g.

When G30 is sent, the firmware will run deployprobe.g if it exists. On Keith's machine, this caused a bunch of XYZ moves to be called (making it look like it was trying to home X and Y) even with a plain G30, usually followed by an 'axis not homed' error message and no Z homing. I only tracked this down because I put the SD card from my machine (which is a broadly similar Cartesian machine) into his Duet, and it worked perfectly on a bench setup with 24V PSU and motors on X, Y and Z. So I knew it was something on the SD card, and eventually noticed the deployprobe.g file!

There were a couple of other minor things that I initially thought were causing issues. First, the crimps in the Molex housing at the probe end of the cable where a small gauge, so weren’t held firmly in the housing and the signal pin particularly was prone to loose connection, though the IR probe showed 1000 when triggered, and I’m still not sure why. Though it worked when I tested it, I recrimped the connector with the correct size crimps. Second, the Duet was mounted on an acrylic frame, which was covered in thick paper, but without standoffs (5mm is recommended) and screwed down so that some pins pierced the paper. Acrylic is generally not electrically conductive (but can have surface treatments that are) but can hold a static charge. However, though some pins were touching (I don't know exactly which ones), I don't think this made any difference.

Edit: config.json added for backup: config.json

Ian

Phaedrux

Well done!

Kayjay

@droftarts Slight clarification though it doesn't really matter now. I did use stand off's for the acrylic board they were underneath it, they were screwed into the existing Rumba holes and then the new holes in the adaptor were spaced for the Duet, there just wasn't room for two lots of stand offs under the base board in the bottom of the Bigbox, there's only 70mm space and 15mm is taken by the electronics cooling fan plus the wiring to the board. It was a bad idea by it's creator and as we discussed I'm mounting the Duet to new holes direct to the bottom of the Bigbox electronics compartment.
Keith

Kayjay

@droftarts The two files as discussed

; General preferences
G90                                     ; send absolute coordinates...
M83                                     ; ...but relative extruder moves
M550 P"Bigbox1"                         ; set printer name

; Network
M552 P0.0.0.0 S1                        ; enable network and acquire dynamic address via DHCP
M586 P0 S1                              ; enable HTTP
M586 P1 S0                              ; disable FTP
M586 P2 S0                              ; disable Telnet

; Drives
M569 P0 S1                              ; physical drive 0 goes forwards
M569 P1 S1                              ; physical drive 1 goes forwards
M569 P2 S0                              ; physical drive 2 goes backwards
M569 P3 S1                              ; physical drive 3 goes forwards
M584 X0 Y1 Z2:4 E3                      ; set drive mapping
M671 X-35:235 Y0:0 S0.5 				; leadscrews at left (connected to Z) and right (connected to E1) of X axis
M350 X16 Y16 Z16 E16 I1                 ; configure microstepping with interpolation
M92 X160.00 Y360.00 Z400.00 E304.00     ; set steps per mm
M566 X480.00 Y480.00 Z24.00 E300.00     ; set maximum instantaneous speed changes (mm/min)
M203 X9000.00 Y9000.00 Z360.00 E1500.00 ; set maximum speeds (mm/min)
M201 X750.00 Y750.00 Z100.00 E5000.00   ; set accelerations (mm/s^2)
M906 X1300 Y1300 Z1300 E800 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 X300 Y200 Z200 S0                  ; set axis maxima

; Endstops
M574 X1 Y1 S1                           ; Set active high endstops
M574 Z1 S2                              ; Set endstops controlled by probe

; Z-Probe
M558 P1 H5 F120 T6000                   ; Set Z probe type to unmodulated and the dive height + speeds
G31 P500 X-25 Y0 Z2.5                    ; Set Z probe trigger value, offset and trigger height
M557 X15:275 Y15:175 S20                ; Define mesh grid

; Heaters
M305 P0 T100000 B4725 C7.060000e-8 R4700 ; set thermistor + ADC parameters for heater 0
M143 H0 S120                            ; set temperature limit for heater 0 to 120C
M305 P1 X200            		; set PT100 for heater 1
M143 H1 S320                            ; set temperature limit for heater 1 to 320C

; Fans
M106 P0 S0 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 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
T0                                       ; select first tool

bed .g

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


G28 							; home
M401 							; deploy Z probe (omit if using bltouch)
G30 P0 X20 Y100 Z-99999 		; probe near a leadscrew, half way along Y axis
G30 P1 X180 Y100 Z-99999 S2 	; probe near a leadscrew and calibrate 2 motors
M402 							; retract probe (omit if using bltouch)

droftarts

@Kayjay looks okay so far, except you need to put in your two Z axis leadscrew locations, using M671. Put it in config.g, after the Z probe section.

You must use the M671 command to define the X and Y coordinates of the leadscrews. The M671 command must come after the M584 command and must specify the same number of X and Y coordinates as the number of motors assigned to the Z axis in the M584 command; and these coordinates must be in the same order as the driver numbers of the associated motors in the M584 command. The M671 command must also come after any M667 or M669 command.

From: https://duet3d.dozuki.com/Wiki/Bed_levelling_using_multiple_independent_Z_motors#Section_Prerequisites

Ian

Kayjay

@droftarts Right I see. I got them in the wrong place, I put the M671 in the Drives section. It seems to work though but I'll move it to the Z probe section. I had a read up about G29 and it's use, I should move it after G28 I think.

droftarts

@Kayjay doesn’t really matter where it is, so long as it’s after M584. Best to use forum, I’m not around much until Wednesday. Have you calibrated Z probe trigger height? See https://duet3d.dozuki.com/Wiki/Test_and_calibrate_the_Z_probe#Section_Calibrate_the_Z_probe_trigger_height

And don’t forget to calibrate extruder, too!

Ian

Kayjay

@droftarts Not done the Z probe trigger yet, I'll make that next on the list. Calibrating the extruder was on my list though but thanks for the reminder. I'll use the forum for any further questions, though I think I'm very near done so if there is anything else I'll probably find the topic with a search. Thanks for everything Ian, I am very grateful and you learnt a little yourself too