No layer adhesion after pause/resume

[Oben221]

Hello, I’ve been battling a issue that after pausing a print and resuming there is little to no layer adhesion. It's almost like the next layer is missed.

This happens on small and large prints. at first i thought it was a slicer issue but this happens on known good prints making me think its a g code error in the Pause.g or the Resume.g however reading the gcode I cannot see an issue.

; pause.g
M83 ; relative extruder moves
G1 E-10 F3600 ; retract 10mm of filament
G91 ; relative positioning
G1 Z5 F360 ; lift Z by 5mm
G90 ; absolute positioning
G1 X0 Y300 F6000 ; go to X=0 Y=0

; resume.g
G1 R1 X0 Y0 Z5 F6000 ; go to 5mm above position of the last move
G1 R1 X0 Y0 Z0 ; go back to the last print move
M83 ; relative extruder moves
G1 E10 F3600 ; extrude 10mm of filament

Has anybody seen this issue before or any ideas?

[jay_s_uk]

@Oben221 what firmware version are you on?
I'm pretty sure i've seen reports of double retractions on pause

[Oben221]

@jay_s_uk firmware was updated in January 2025 the main board is a duet 2 ethernet (I will get the version number when I’m home tonight.)

I don’t think it’s a double retraction as the print I first found this issue on was a large 280mm x 280mm print and it was the same on the entre layer not just the next few movements. I originally thought it did not go back to the same Z hight but after some tests it does this fine. My current line of thought is its under extruding until the slicer restates the feed rate but looking in the gcode this lines up also so I’m a bit lost.

If there is no pause in the print then all if fine but if M25 or M226 is called from g code or the webpage then I get this "missing" layer.

[dc42]

@Oben221 is there backlash in your Z axis? Unless you have Z hop on travel moves enabled in either the slicer or M207, after the first layer the Z axis normally only moves up (or the bed down) to get to the next layer. However, when you pause the Z axis raises 5mm, and when you resume it goes back to the original coordinate; so the last Z move before resuming the print is down (or the bed up). If there is backlash in the Z axis, the nozzle will be too high at the start of that layer by the amount of the backlash.

[Oben221]

@dc42 I dont know why i didn't think about backlash. commented out the extra z movments and perfect!
Thank you.