I faced some issues today with my extruder: it started skipping steps due to a clogged nozzle. Sadly enough, that started when I was already a few hours in the print. Pondering how handy it would be that when the extruder engine starts skipping steps, it would just pause the print and wait for user interaction, I wonderend if I couldn't use sensorless homing for it.

The stepperdrivers can detect when there is a stall (within a certain amount ofcourse ). I see some practical issues because for sensorless homing I drop the current the motors get, something I obviously don't want to do while printing for the extrudermotor. I havent found really a fix for that part, but I thought, let's just put the idea here and maybe a bright soul has a solution.

@dc42 i think i finally found it When the ABL finishes, it puts the Z on +10 and starts moving to x20y20, when it reaches that point, the bed moves to z 0.2, but, the acceleration/speed of the Z-axis seemed to be too high, which made the motors skip steps. For the normal z-hop the acceleration is however no problem.

Seems adjusting the accelerationsettings solves it.

@dc42 as soon as the current print is finished, i'll give that a spin and keep you posted here about the results

Firmware Name: RepRapFirmware for Duet 2 WiFi/Ethernet
Firmware Electronics: Duet WiFi 1.02 or later
Firmware Version: 2.02RC2(RTOS) (2018-09-07b2)
WiFi Server Version: 1.21RC4(08b3)
Web Interface Version: 1.22.3

and the fileupload is refusing a bit:

wetransferlink for the configfiles

So I have this really weird issue which i just can't get figured out.

The problem: when I start a print, all goes well. The printer starts with fixing the tilt on one plane, does a small ABL, primes and prints along, so far so good. However: after this print has finished and I want to start a second print, this print starts with a z height of +2 (eg: in stead of 0.2, because the first layer is 0.2mm, the printer starts on 2.2, which results in some nice airprinting no need saying ).

The samen happens when i cancel a print and start a new one. Restarting the duet completely solves it for the next print.

I have digged through the configfiles but can't figure out where that +2 comes from.

Configfiles for my Duet Wifi:
[0_1544888213532_download.zip](Uploading 0%)

My startup g-code is:

; Startup Gcode
M83
M140 S[first_layer_bed_temperature] ; set bed temperature
M190 S[first_layer_bed_temperature] ; wait for temperature
M104 S[first_layer_temperature]
M561 ; Clear any bed transform
G32 ; Do a single probe
G29 ; Load heightmap (you can use G29 S1 instead)
G1 Z20.0 F100 ; Move Z to 20
G1 X10 Y10 F900 ; Move Head to front left
M109 S[first_layer_temperature]
G0 X5 Y10 F9000 ; Go to front
G0 Z0.2 ; Drop to bed
G92 E0 ; zero the extruded length
G1 X40 E25 F100 ; Extrude 25mm of filament in a 4cm line
G92 E0 ; zero the extruded length
G1 E-1 F500 ; Retract a little
G1 X80 F4000 ; Quickly wipe away from the filament line

My End-gcode is:
G10 P0 R-273.15 S-273.15 ; Turn off Tool0
M140 S0 ; Turn off Bed
M109 S0
M106 S0 ; Object fan off
G1 X0 Y0 ; Move Z to Z210
G92 E0 ; Zero Extruder
G1 E-2 F300 ; Retract 2mm
G92 E0 ; Zero Extruder
M84 ; All motors Off

@scachi let me test that next

I now tried without the resistor between ground / signal wire (since duet 'bragged' about how idiotproof the board is, i felt lucky

results now:
19:18:03G30 S-1
Stopped at height 0.000 mm
19:17:56G0 Z5
19:17:40G30 S-1
Stopped at height 0.065 mm
19:17:32G0 Z5
19:17:24G30 S-1
Stopped at height -0.039 mm
19:17:19G0 Z5
19:17:11G30 S-1
Stopped at height 0.005 mm
19:17:04G0 Z5
19:17:00G30 S-1
Stopped at height -0.013 mm

This seems to be somewhat normal

18:53:47G30 S-1
Stopped at height -0.762 mm
18:53:43G0 Z5
18:53:35G30 S-1
Stopped at height -0.647 mm
18:53:30G0 Z5
18:53:26G30 S-1
Stopped at height -0.641 mm
18:53:23G0 Z5
18:53:17G30 S-1
Stopped at height -0.757 mm

Results after putting the trigger value up to 70 in stead of the 10 I started with. I followed the guide to setup the 3dtouch (bltouch guide actually) which stated that the trigger value had to be low, since the pulse of the sensor is very short. Seems it however has a negative effect on the output when you go low/very low.

@drammy some time ago i had some issues here, which i fixed by using x16 with interpolation. The movement is pretty much as smooth as i could wish for.

As of feeling the motors: tested it here and i can feel something but barely, not a level that i can imagine it would cause any issue.

For the oozing: i first configured my printer here to print straight lines, then started tuning the instantDV and acceleration. Last steps: in your slicer up travelspeed (helps bigtime against stringing) and start with retraction settings (there are some testfiles for that on thingiverse)

@drammy in that way The pulsing is i presume some vibration-ish you feel right? Or like a small electric flow (do you start dancing funny every 0.3 seconds when you touch it )