Stop Cura (4.4 & 4.5) lowering the nozzle before printing.

[Darren_Lines 0]

Hi guys,

 

Since Cura 4.4, some G-code is added somewhere that lowers the nozzle before going to the start point of the print job. Cura 4.3 and previous did not do this.

 

Does anyone know where this code is added so that I can remove it. The issue is that on some jobs, lowering the nozzle before getting to the start point will hit my nozzle in to the crocodile clips that hold the glass bed in place. I guess this is an oversight as the coders think that everyone is using magnetic beds now?

 

I know that it's not in the printer or extruder G-code in the machine settings. This is added after that. Any help to fix this bug would be greatly appreciated.

Edited April 4, 2020 by Darren_Lines

[burtoogle 508]

Hi, could you please save a sample project file (File -> Save) and attach the .3mf to this thread, thanks.

[Darren_Lines 0]

No problem. The Start G-code I currently have in the printer machine settings is

 

M117 Initialising...
G21 ;metric values
G90 ;absolute positioning
M82 ;set extruder to absolute mode
M107 ;start with the fan off
G28 X0 Y0 ;move X/Y to min endstops
G28 Z0 ;move Z to min endstops
G92 E0 ;zero the extruded length
M117 Cleaning... ;Put cleaning message on screen
; - reposition nozzle
G1 Y10 Z5 F10000 ;raise nozzle 5mm and move along Y by 10mm
; - continue cleaning
G1 Z1 ;Move nozzle close to the bed
G1 E10 ;extrude 10mm of filament
G1 Z15 F15000 E5 ;Move up 15mm fast, while extruding 5mm
G92 E0 ;zero the extruded length again
G1 X0 Y0 ;home the nozzle
M117 Printing...

I have changed this to move the cleaning operation so that the cleaned nozzle didn't lower its self back in to the extruded filament. The lowering happens after the G1 X0 Y0 command at the end.

Visor_NHS.3mf

[burtoogle 508]

Hi, sorry for the slow response, it's been a busy day. So, I think this behaviour has been introduced by a recent revamp of the retraction/z-hop code. Arguably, it's a regression. The only workaround I can suggest is to turn off z-hop. For this particular print, that's of no consequence (I think) because it doesn't appear to do any other z-hops in the print. I recommend you open an issue at the cura github as this should get a proper fix.

 

[Darren_Lines 0]

Thanks for the reply and your help. I can confirm that disabling the Z-hop did stop the unwanted movement. I'll raise an issue on github.