Relative or Absolute Extrusion?

Am I right in thinking that to swap from Relative to Absolute values for extrusion, the only thing required - apart from making sure that the slicer software is set up appropriately - to change the M83 command to M82 on the assumption that the firmware is MARLIN?

I seem to remember/think that back in the Sprinter days, swapping from one system to the other was not possible and that correct selection of relative or absolute extrusion in the slicer programme was key to getting the GCode right.

The reason I ask is that I am trying out CURA for the first time which is written to provide GCode using absolute extruder values, that is, there is no choice to go relative which is what I have been using since the beginning.

Thank you,
Alan

If you look through the Cura files for a file called settings.py you will be able to open it in a text editor and change the settings to use Relative extrusion. If you want to use Absolute on your Marlin you can open the advanced config and change it to default to Absolute instead of relative.

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Sublime: Brilliant - thank you. I have made the changes which you suggested and which now make CURA consistent with the other slicers on my computer (Slic3R, Kisslicer and Skeinforge). Although I haven't had chance to try it out, the resulting GCODE looks a lot better in that the E figures are similar to those in GCODE produced by Skeinforge.

A knock on effect - and I cannot immediately see a reason for this - is that the CURA display at the end of the slicing operation now looks as I expected it. Before, I was getting a screen full of colours rather than a screen just showing my object in colour. It is as if CURA knew that I was set up to use relative extrusion by default somehow - the mass of colour representing the stack of extruded filament which I was getting. Having made the changes which you suggested, I can use all of the display options as described in the Ultimaker Screencast.

Alan

Edited 1 time(s). Last edit at 03/22/2013 04:01AM by Alzibiff.

If you had M82 or M83 (not sure which one) in the start gcode it would have set the gcode viewer in relative mode even though the gcode produced was absolute. The reason I know all of this is because the only reason the gcode viewer works in relative mode at all is because I wanted it and found the reason it did not work and Daid fixed it. I added a relative extrusion check box in my version of Cura and it would be really easy to add it to yours. Its just four lines of code [github.com] plus the two you already changed to get it to work.

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FFF Settings Calculator	Gcode post processors	Geometric Object Deposition Tool Blog
Tantillus.org	Mini Printable Lathe	How NOT to install a Pololu driver