Adding option to switch to relative extrusion for Pause at Height

[valemaio2 4]

Hi, if this is not the correct place to suggest a change in Ultimaker Cura, please just point me in the right direction.

 

I was playing with the Pause at Height feature in Cura and I noticed that the gcode inserted switched the print to extrusion absolute mode. My printer uses relative mode, so it took me a while to figure out why it wasn't working. I can manually modify the gcode myself, changing all M82 command to M83, but it would be nice to have the option of switching between relative and absolute in the plugin itself.

[GregValiant 1,248]

In the Cura folder ...C:\Program Files\Ultimaker Cura 4.X\plugins\PostProcessingPlugin\scripts\PauseAtHeight.py

The PauseAtHeight.py file can be opened in a text editor.  The following line is near the end:

prepend_gcode += self.putValue(M = 82) + " ; switch back to absolute E values\n"

Change the 2 to 3, save the file, restart Cura.  I'm not a Python guy but you should be good to go.

Cura 4.7 PauseAtHeight allows you to add a gcode command "Gcode after the pause" but it goes in as the first line after the pause which doesn't work since the M82 is a few lines later.

[valemaio2 4]

Thank you GregValiant, that seemed to have done the trick.

[edankleef 1]

For people facing the same problem but wanting the "Pause at height" script to work with both absolute and relative extrusion (depending on your "Relative Extrusion" setting under "Special Modes"):

 

Replace the following line in PauseAtHeight.py file

 

prepend_gcode += self.putValue(M = 82) + " ; switch back to absolute E values\n"

 

with the following lines

 

extrusion_mode_string = "absolute"
extrusion_mode_numeric = 82

extruders = list(Application.getInstance().getGlobalContainerStack().extruders.values())
relative_extrusion = extruders[0].getProperty("relative_extrusion", "value")
if relative_extrusion:
  extrusion_mode_string = "relative"
  extrusion_mode_numeric = 83

prepend_gcode += self.putValue(M = extrusion_mode_numeric) + " ; switch back to " + extrusion_mode_string + " E values\n"

 

Hope this helps.

Edited April 3, 2021 by edankleef

[GregValiant 1,248]

Maybe you should post that over on Github.  It looks to be a worthwhile addition.

 

Is there an advantage to using Volumetric vs Linear?  It seems like it's just an internal math thing.

[edankleef 1]

That is a good idea, I have created a pull request.

Your question I do not understand however. Do you mean why relative VS absolute extrusion? I use relative extrusion for easier post processing, which allows me to use the plugin OctoPrint-Cancelobject.

[GregValiant 1,248]

That I understand (relative vs absolute).  The E is always in sync no matter where in a file you start a print from.