GCode for Small Retraction at End of Print

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getSurreal
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GCode for Small Retraction at End of Print

Post by getSurreal » Sun Dec 31, 2017 4:56 am

I noticed after a successful print that my next print would not start extruding until partially into the print.

What I found is that the gcode at the end of the print using the defaults provided with Simplif3D, that should just be retracting it 1mm, retracts for a long time completely pulling the filament out.

G1 E-1.0000 F6000

When I run that manually it retracts for more than 10 seconds.

Bug? Any suggestions?

MakerGear M3 Independent Dual

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insta
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Re: GCode for Small Retraction at End of Print

Post by insta » Mon Jan 01, 2018 8:41 pm

You are in absolute position mode, and are probably several meters into the print. You need a G91 before that to switch to relative mode.
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ednisley
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Re: GCode for Small Retraction at End of Print

Post by ednisley » Tue Jan 02, 2018 1:35 am

getSurreal wrote:my next print would not start extruding until partially into the print
Printing a skirt before starting the object is always a Good Thing.

I set Slic3r to extrude 15 mm of filament or make three loops around the object, whichever consumes more plastic. When it's done with the skirt, the hot end is properly pressurized, the plastic flows smoothly, and everything Just Works.

getSurreal
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Re: GCode for Small Retraction at End of Print

Post by getSurreal » Tue Jan 02, 2018 1:50 am

I see when I run it manually that's why it would do that. Looking at the gcode of my print it resets it beforehand though.

Code: Select all

G92 E0
G1 E-1.0000 F6000
; layer end
M104 S0 ; turn off extruder
M104 S0 T0
M104 S0 T1
M140 S0; turn off bed
G1 Z200 Y0 F10000
M605 S0 ;x carriage mode to independent control
G28 X ;home x axes
M106 S0
M84 ; disable motors

getSurreal
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Re: GCode for Small Retraction at End of Print

Post by getSurreal » Tue Jan 02, 2018 1:55 am

Printing a skirt before starting the object is always a Good Thing.
It does do a priming run before the print. The problem is that the filament is just resting on top of the gear and randomly grabs back a hold of it.

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ednisley
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Re: GCode for Small Retraction at End of Print

Post by ednisley » Tue Jan 02, 2018 5:07 pm

getSurreal wrote:a priming run before the print
Priming shoves enough plastic into the hot end to fill it up. The Skirt uses normal extrusion against the platform to stabilize the hot end pressure. You need both before printing an object to avoid exactly the not-extruding-plastic-soon-enough problem you described.

What happens at the end of a print is irrelevant, unless the last steps retract the filament far enough to put semi-molten plastic under the drive gear. If so, reduce the final retraction distance.

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