Extruder goes crazy at the end of print

superpotatofudge · 15 Jun 2017, 15:09

So I sliced and print this XYZ calibration cube and for some reason when the cube is done, before homing, the extruder goes ultra high speed in reverse! It reverses long enough to pull at least 200% of the length of the filament from the Bowden tube…this is on a Rostock Max V2.
I cut out everything after the skirt and layer 1 up to layer 10..which is the last(top) layer in this case. Thoughts? What am I missing that is likely staring me RIGHT in the face here?

https://pastebin.com/nNMzdpa7

Dougal1957 · 15 Jun 2017, 15:43

you have your slicer set opposite the firmware as regards to relative or absolute extrusion.

deckingman · 15 Jun 2017, 16:48

@ superptatofudge at the beginning of the file, you've got M82 to set the extrusion to absolute and the gcode uses absolute coordinates which is fine. The problem is at the end of the file. The last G1 print move is this G1 F2340 X19.149 Y19.149 E587.39239.

After that you have this
G91
G1 Z10 E-3.0 F12000
G90

The G91 sets the axes to relative but not the extruder. So the extruder tries to move from the absolute position of Plus 587.39239 to minus 3.0 hence an effective retraction of 590.39239 mm.

What you need is an M83 command as well as the G91 to set the extruder to relative as well as the axes. Then it will retract 3.0mm relative to where it was the last time it moved. Alternatively try to get matter control to do an absolute retraction so after the G91 you' have something like G1 Z10 E584.39239. I've never played with Matter Slicer so can't advise on how to do it.
HTH

superpotatofudge · 19 Jun 2017, 19:53

HAHA! I knew it was staring me in the face. I couldn't see the missing M83 for the life of me! Yea I have no idea how to make MatterSlice do an absolute retract at the end, so I'm just adding in the M83…should work fine now. Thanks!!