G92 E0 and Slic3r problems

[Bernie N]

Hi All,

I'm trying to get Slic3r to work with a Replicator (dual head). I modified the GCode.pm file to make sure the T0 and T1 specifications were added for setting the toolhead temperatures. Made sure that the T1 to T0 transition was M108 T0/T1. (I can post those modifications for those that want it.) The problem I'm having is during a dual-extrusion print, the g-code is uses is a G92 E0 which resets the extrusion "counter" per layer. The printer proceeds to jog right about 3cm per layer. I can't understand why this is happening, but when I remove the G92 command, it doesn't do the weird jog and prints the next layer on top of the previous one. Any ideas? Here are some parts of the g-code. Thanks for any help anyone can offer!

Bernie

(**** end of start.gcode ****)

G90 ; use absolute coordinates

G21 ; set units to millimeters

M106 S179 ; enable fan

G1 F1800.000 E-3.00000 ; retract

G1 Z0.170 F7800.000 ; move to next layer (0)

G1 F1800.000 E-5.00000 ; retract for tool change

M108 T1 ; change extruder

G92 E0 ; reset extrusion distance

G1 E-3.00000 ; retract

G1 E-5.00000 ; retract for tool change

M108 T0 ; change extruder

G92 E0 ; reset extrusion distance

G1 X-28.337 Y11.837 F7800.000 ; move to first perimeter point

G1 F1800.000 E5.00000 ; compensate retraction

G1 X-28.337 Y-11.837 F2520.000 E5.59045 ; perimeter

G1 X-4.663 Y-11.837 E6.18090 ; perimeter

(etc)

G1 X-3.970 Y-12.530 E11.01861 ; perimeter

G1 X-3.970 Y12.530 E11.64362 ; perimeter

G1 X-28.547 Y12.530 E12.25658 ; perimeter

G1 F1800.000 E7.25658 ; retract for tool change

M108 T0 ; change extruder

G92 E0 ; reset extrusion distance

G1 X-27.649 Y11.833 F7800.000 ; move to first fill point

G1 F1800.000 E5.00000 ; compensate retraction

G1 X-28.333 Y11.149 F3360.000 E5.02430 ; fill

G1 X-28.333 Y10.655 F7800.000 ; move to first fill point

G1 X-27.155 Y11.833 F3360.000 E5.06616 ; fill

(etc)

G1 X-4.667 Y-10.160 F3360.000 E45.19017 ; fill

G1 X-4.667 Y-10.655 F7800.000 ; move to first fill point

G1 X-5.845 Y-11.833 F3360.000 E45.23203 ; fill

G1 X-5.351 Y-11.833 F7800.000 ; move to first fill point

G1 X-4.667 Y-11.149 F3360.000 E45.25632 ; fill

G1 F1800.000 E40.25632 ; retract for tool change

M108 T1 ; change extruder

G92 E0 ; reset extrusion distance

M106 S243 ; enable fan

G1 Z0.440 F7800.000 ; move to next layer (1)

M108 T0 ; change extruder

G92 E0 ; reset extrusion distance

G1 X-4.990 Y-11.510 ; move to first perimeter point

G1 F1800.000 E5.00000 ; compensate retraction

G1 X-4.990 Y11.510 F3600.000 E6.20264 ; perimeter

G1 X-28.010 Y11.510 E7.40528 ; perimeter

(etc)

[Dan Newman]

Owing to toolhead offset handling, I'm pretty sure that G92 is not
working as expected in the Replicator's firmware. (Getting the
reported position back certainly returns a not quite expected result:
the current position offset by the current toolhead's offset.)

The workaround would be to not generate gcode which uses the G92
command. (I believe that KISSlicer is having this same difficulty.)

Dan

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