Printer pausing at start of each layer.

[JJJJ]

Hi, the printer keeps pausing at the start of each layer and causes massive blobs on the z seam.

Hardware:

• Tractus T1250, 1m boden tube is around 1 metre long and it is old and I'm going to replace it. Hemera extruder.

• E3D v6 hot end.

• Duet2 v1.03

Firmware:

• RepRapFirmware for Duet 2 WiFi/Ethernet FIRMWARE_VERSION: 3.5.1 ELECTRONICS: Duet Ethernet 1.02 or later FIRMWARE_DATE: 2024-04-19 14:40:46

• Paneldue 1.21.3

I am not sure what is causing it, I thought it might be something to do with power loss recovery saving a reference point but I don't think I have that enabled in my config.

I thought it could be related to retraction but I have retract at layer change turned off and when the printer stops moving so does the extruder so I don't think it is that.

The minimum layer time is 0.1s. Retraction distance 5mm, speed 60

I also printed in vase mode and it worked fine, no blobs. But obviously, in vase mode, there is no stopping for each layer.

I have not turned on Pressure Advance.

No matter what speed I print at the printer will pause for the same amount of time, but on faster prints, the blob is much bigger.

I have attached pictures and a video. In the pictures it looks like it's under-extruding at the start of the layer and then by halfway around its back to normal.

So does anyone have any idea what could be causing it? I am probably missing something fairly obvious. Thanks

Test Print Video

; Configuration file for RepRapFirmware on Duet 2 Ethernet
; executed by the firmware on start-up
;
; generated by RepRapFirmware Configuration Tool v3.5.4 on Fri Aug 16 2024 12:20:56 GMT+0100 (British Summer Time)
 
; General
 
G90                        ; absolute positioning
M83 ; relative extruder moves
M550 P"T1250" ; set hostname
 
; Accessories
M575 P1 S0 B57600 ; configure PanelDue support
 
; Network
M552 P0.0.0.0 S1 ; configure Ethernet adapter
M586 P0 S1 ; configure HTTP
 
; Smart Drivers
M569 P0 S1 D2 ; driver 0 goes forwards (extruder 0)
M569 P2 S0 D2 ; driver 2 goes backwards (X axis)
M569 P3 S0 D2 ; driver 3 goes backwards (Z axis)
M569 P4 S0 D2 ; driver 4 goes backwards (Y axis)
 
; Motor Idle Current Reduction
M906 I40 ; set motor current idle factor
M84 S30 ; set motor current idle timeout
 
; Axes
M584 X2 Y4 Z3 ; set axis mapping
M350 X16 Y16 Z16 I1 ; configure microstepping with interpolation
M906 X1700 Y1700 Z1700 ; set axis driver currents
M92 X160 Y160 Z160 ; configure steps per mm
M566 X30000 Y30000 Z30000 ; set maximum instantaneous speed changes (mm/min)
M203 X36000 Y36000 Z36000 ; set maximum speeds (mm/min)
M201 X4000 Y4000 Z4000 ; set accelerations (mm/s^2)
 
; Extruders
M584 E0 ; set extruder mapping
M350 E16 I1 ; configure microstepping with interpolation
M906 E1100 ; set extruder driver currents
M92 E357.14286 ; configure steps per mm
M566 E18000 ; set maximum instantaneous speed changes (mm/min)
M203 E18000 ; set maximum speeds (mm/min)
M201 E4000 ; set accelerations (mm/s^2)
 
; Kinematics
M665 L457.600 R267.060 B175 H678.996 ; set delta radius, diagonal rod length, printable radius and homed height
M208 Z0 S1 ; set minimum Z
M666 X-0.23 Y0.20 Z0.03 A0 B0 ; endstop adjustments and XY tilt, can be determined using auto calibration as well
 
; Probes
M558 K0 P8 C"e0stop" H5 F300 T18000 R0.2 A3 ; configure digital probe via slot #0
G31 P100 X0 Y0 Z-0.3  ; set Z probe trigger value, offset and trigger height
 
;Bed Mesh
M557 R170 S80 ;bed probe grid
 
; Endstops
M574 X2 P"xstop" S1 ; configure X axis endstop
M574 Y2 P"ystop" S1 ; configure Y axis endstop
M574 Z2 P"zstop" S1 ; configure Z axis endstop
 
; Sensors
M308 S0 P"bedtemp" Y"thermistor" A"Heated Bed" T100000 B4725 C7.06e-8 ; configure sensor #0
M308 S1 P"e0temp" Y"thermistor" A"Nozzle" T100000 B4267 C7.06e-8 ; configure sensor #1
 
; Heaters
M950 H0 C"bedheat" T0 ; create heater #0 (bed)
M143 H0 P0 T0 C0 S140 A0 ; configure heater monitor #0 for heater #0
M307 H0 R0.337 K0.353:0.000 D2.69 E1.35 S1.00 B0 ; configure model of heater #0 
M950 H1 C"e0heat" T1 ; create heater #1 (Nozzle)
M143 H1 P0 T1 C0 S285 A0 ; configure heater monitor #0 for heater #1
M307 H1 R2.43 D5.5 E1.35 K0.56 B0 ; configure model of heater #1
 
; Heated beds
M140 P0 H0 ; configure heated bed #0
 
; Fans
M950 F0 C"fan0" ; create fan #0
M106 P0 S0 L0 X1 B0.1 ; configure fan #0
M950 F1 C"fan1" ; create fan #1
M106 P1 S0 B0.1 H1 T50 ; configure fan #1
M950 F2 C"fan2" ; create fan #2
M106 P2 S1 L0 X0.6 B0.1 ; configure fan #2
 
; Tools
M563 P0 D0 H1 F0 ; create tool #0
M568 P0 R0 S0 ; set initial tool #0 active and standby temperatures to 0C
 

[droftarts]

@JJJJ Can you post the Gcode?

Edit: add .txt on the filename, and you can upload it here.

Ian

[JJJJ]

@droftarts

Here you go:

Round cube fast .txt

[droftarts]

@JJJJ In your config.g, you have:

M566 X30000 Y30000 Z30000 ; set maximum instantaneous speed changes (mm/min)
M203 X36000 Y36000 Z36000 ; set maximum speeds (mm/min)
M201 X4000 Y4000 Z4000 ; set accelerations (mm/s^2)

For M566, this is way too high. It means that the printer can immediately go at 500mm/s. Delta printers are fast, but even they can't do that. M566 X1200 Y1200 Z1200 is a more sensible setting.
M203 is fine, but your M201 acceleration could be a lot faster, try M201 X10000 Y10000 Z10000

The Gcode Cura is producing is actually overriding the M566, with a much more sensible value.

However, I think the blob is happening on layer change. You've got this at the first layer change:

...
G1 X-15 Y24.8 E0.02855
G1 X0.00 Y24.8 E0.74835
M566 X1800 Y1800
G0 F3600 X0.5 Y24.8
G0 X0.5 Y23.8
;MESH:NONMESH
G0 F0 X0.5 Y23.8 Z0.5
G0 F3600 X0.00 Y24.4
;TIME_ELAPSED:12.247635
;LAYER:1
M106 S255
M566 X1200 Y1200
;TYPE:WALL-INNER
;MESH:100mm_Rounded_Cube.stl
G1 F8100 X14.985 Y24.4 E0.4984
...

The strange line is the G0 F0 X0.5 Y23.8 Z0.5 line. This is a zero speed Z move. To avoid stopping forever, RRF has a minimum speed of 0.5mm/sec, or 30mm/minute, so I think the 'pause' is just a really slow Z move. Cura is putting this in on every layer change, so it must be something in your Cura settings. It's been a while since I used Cura, so I'm not sure why it's doing this, or where the setting is, unfortunately.

Ian

[JJJJ]

@droftarts That very helpful thank you. I will adjust those settings and I will try octoprint and see what happens.

[JJJJ]

@droftarts Apparently if z hop speed is 0 that's what causes that pause. I changed that number and it changed that gcode line to actually have a speed so I think that's what was causing it.

I think I just forgot to add a number when I was setting up the profile.

Thanks for your help as I would of never spotted that in the gcode.

[droftarts]

@JJJJ I'm glad you found what was causing it! I'm surprised it uses the Z Hop Speed as the Z travel speed, though.

Ian

[JJJJ]

@droftarts Yeah its strange, still got to tweak the settings as im getting a very large seam still, but its not pausing now.

[droftarts]

@JJJJ You will probably want to tune pressure advance. See https://docs.duet3d.com/User_manual/Tuning/Pressure_advance

Most slicers also have an end of perimeter 'gap' setting to stop extrusion slightly early, which can be worth playing with.

Ian

[Phaedrux]

@JJJJ said in Printer pausing at start of each layer.:

@droftarts Yeah its strange, still got to tweak the settings as im getting a very large seam still, but its not pausing now.

I'm guessing your cura has retract at layer change turned off.