Cura & Duet 3 relative extrusion issue

LeonMF

OK, I tried searching and didn't see anyone else having this problem.

I have a Duet 3 (MB6HC) w/SBC running version 3.3.

When I slice in Cura 4.12.1 in relative extrusion mode, it sets the extrusion to absolute (this is by design), does the startup code, then sets it back to relative. Theoretically, this should be fine. Especially since I set M83 immediately in my startup script (and twice more for good measure). Sometimes this works and prints fine, sometimes the system never exits absolute mode and the printer doesn't extrude anything because all the extruder movements are relative. However, commenting out the M82 line in the gcode file makes everything work fine.

The code from the slicer that doesn't work

T0
M190 S80
M104 S245
M109 S245
M82 ;absolute extrusion mode
M98 P"Cura_Startcode.g"
M83 ;relative extrusion mode
G1 F1500 E-1
;LAYER_COUNT:36

my Cura_Startcode.g

M83 ;Need to set relative extrusion mode. Override Cura set to absolute.
G1 X0.0 Y0.0 Z1.0 F2000.0 ; prepare to prime
G92 E0 ; reset extrusion distance
G1 Z0.2 F1000.0
G1 X60.0 E9.0  F1000.0 ; priming
G1 X125.0 E12.5  F1000.0 ; priming
G1 Z0.5 F1000.0
M83
G92 E0 ; reset extrusion distance
M83

Just commenting out line 5 in the first code block above seems to make everything work fine.

Am I doing something dumb or have I found some obscure bug?

LeonMF

This person had the same problem I do but I'm unclear what the resolution to their problem was:

https://forum.duet3d.com/topic/22464/m83-problem/4

Phaedrux

@leonmf said in Cura & Duet 3 relative extrusion issue:

I have a Duet 3 (MB6HC) w/SBC running version 3.3.

There are two things that we can do testing wise to try and narrow down the problem.

Would you be able to test in standalone mode to remove the SBC from the equation?

https://duet3d.dozuki.com/Wiki/Getting_Started_With_Duet_3#Section_Running_in_standalone_mode

Next would be to test with the recent 3.4 beta versions both as standalone and SBC.

https://duet3d.dozuki.com/Wiki/Getting_Started_With_Duet_3#Section_Software_Installation

dc42

@leonmf said in Cura & Duet 3 relative extrusion issue:

M82 ;absolute extrusion mode
M98 P"Cura_Startcode.g"
M83 ;relative extrusion mode

Please try the following:

Remove the two M83 commands in lines 8 and 10 of Cura_Startcode.g. They won't have any effect, because when the macro completes extrusion will be restored to absolute, because that was the state before the macro was executed.
In the start GCode try putting a G4 P10 command between the M98 call and the following M83 command. I'm taking a guess here, but I suspect that the restoration of absolute extrusion after the macro finishes is getting overlapped with the M83 command that switches it to relative extrusion.

You could also try switching to the unstable feed on the package server and upgrading to 3.4.0beta7 because I know some issues to do with macros and SBC have been fixed since version 3.3.

danzaywer

I have the same situation, my solution is a postscript that replace "M83" with ";M83".

LeonMF

@dc42 The information that the macros revert to previous mode was key.

I just added an extra M83 in my slicer start script after my macro call and removed all the superfluous M83s that I had added to the startcode. That does mean an M83 followed by an M83 but it seems to work.

If you need I can do some extra testing but, for now I seem to be working fine.

Thanks!