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Dual extruder mode ...
 
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Dual extruder mode gcode extrusion values incorrect for early layers


Tyler Habowski
(@cobalt700)
New Member Customer
Joined: 2 months ago
Posts: 1
Topic starter  

Hello,

I started using Stratos 1.0.0 recently and ran into a problem with dual extrusion mode on my Sigma R19 where it would always start the first layer not extruding enough initially and to get it to work I would have to manually pause and purge the extruders out every print on the first layer so they would be properly primed in again. After that, it works fine.

To narrow this issue down, I re-downloaded Stratos, started from all stock settings, etc and sliced an extremely simple dual extrusion model that is just several 0.2mm tall rectangles layered on top of eachother with each layer assigned to alternating extruders and sliced at 0.2mm layer height so that when it prints it just alternates between the two extruders every layers and does a simple small rectangle, no skirt / brim / infill / extra walls / top bottom layers / etc. I attached the output gcode for this in the attached 'layers_stock.gcode'.

I figured out that the issue is fairly fundamental and I'm quite confused what the intent is supposed to be here or if this is indeed a bug. Basically, for the first time each extruder is used it starts printing with the extrusion amount starting from exactly 0mm. See excerpt from the attached gcode file below. As you can see, when it starts printing WALL-OUTER it's exactly 8mm deficient on filament. If I comment out the G92 E0 line then it all works fine.

T1
G92 E0
G91
G1 Z0.2 F12000
G90
G92 E-8
G1 E0 F1000 ;Restore E position
G1 E0.8 F100;defaultpurge
G92 E0
G4 S3
G1 E-8 F1000
G92 E0
M105
M109 S190
M104 T0 S192.5
M106 S51
M104 T0 S195
M204 S690
M205 X10.94 Y10.94
;MESH:dual_layered_200um_top.STL
G0 F5850 X105 Y297 Z0.8
G1 F600 Z0.4
G0 F5850 X105 Y147.78
G0 X109.7 Y147.73
G0 X109.8 Y147.8
M204 S352
M205 X7.03 Y7.03
;TYPE:WALL-OUTER
G1 F1050 E0
G1 F900 X100.2 Y147.8 E0.12039
G1 X100.2 Y143.2 E0.17807
G1 X109.8 Y143.2 E0.29846
G1 X109.8 Y147.8 E0.35615

So what it should do it start at 8mm when it actually starts printing (which is the nozzle switch retraction distance) instead of 0 because it had just retracted to do the nozzle switch retract and then did a G92 E0 so going to 0 will result in no extrusion. The rest of the layers do this properly as shown below:

T1
G92 E0
G91
G1 Z0.2 F12000
G90
G92 E-8
G1 E0 F1000 ;Restore E position
G1 E0.8 F100;defaultpurge
G92 E0
G4 S3
G1 E-8 F1000
G92 E0
M106 S153
;MESH:dual_layered_200um_top.STL
G0 F9000 X109.8 Y147.8 Z1.2
M204 S270
M205 X4.69 Y4.69
;TYPE:WALL-OUTER
G1 F600 Z0.8
G1 F525 E8
G1 F900 X100.2 Y147.8 E8.12039
G1 X100.2 Y143.2 E8.17807
G1 X109.8 Y143.2 E8.29846
G1 X109.8 Y147.8 E8.35615

 

I can't simply edit the extruder start gcode because it's the actual printing extrusion code that is off so there's not much I can do. I can't imagine that this is a bug that just straight up prevents doing dual extrusion prints properly but I'm also at a loss why it would be like this, does anyone have an idea and how to fix this properly?

Thanks!


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