BUG in GCODE: Missing retraction in some movements
 
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BUG in GCODE: Missing retraction in some movements  

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Zbig
 Zbig
(@zbig)
New Member
BUG in GCODE: Missing retraction in some movements

PrusaSlicer 2.3.0 (Windows 64bit)

Ive found bug in generated GCode. Some movements were made without previous retraction, even when move length is longer than "minimum travel after retraction" parameter (2mm in my case).

Bad code looks like that:

G1 X85.779 Y107.154 E1.80653
G1 X85.919 Y95.819 F4800.000
;TYPE:External perimeter    

 Second instruction (movement without extration) is 11,3mm  so it is long enough and should be made with retraction.

Btw. In other part of the file there is proper retraction (1.5mm) before movement like this (retraction is in second line):

G1 X80.607 Y89.951 E12.26002
G1 E10.76002 F2100.000  
G92 E0    
G1 X88.792 Y97.063 F4800.000
G1 E1.54000 F2100.000  
;TYPE:External perimeter    
G1 F1800.000    
G1 X89.267 Y96.637 E1.59801

It is 

 

 

 

Posted : 08/05/2021 9:42 pm
fuchsr
(@fuchsr)
Noble Member
RE: BUG in GCODE: Missing retraction in some movements

Hi, not much point in posting here. It's not where the developers hang out. PRUSA has a GitHub site for PrusaSlicer. You should file a bug report there,  if you want the developers to see it. 

Posted : 08/05/2021 11:32 pm
bobstro
(@bobstro)
Illustrious Member
RE: BUG in GCODE: Missing retraction in some movements

Retractions are not made on every move. Several factors affect where they occur. That last G1 is either extruding 1.59801mm more filament if the extruder is in relative mode, or 12.26002-1.59801 (-10.66201mm) if in absolute mode. 

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 09/05/2021 2:08 am
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Zbig
 Zbig
(@zbig)
New Member
Topic starter answered:
RE: BUG in GCODE: Missing retraction in some movements
Posted by: @bobstro

Retractions are not made on every move. Several factors affect where they occur. That last G1 is either extruding 1.59801mm more filament if the extruder is in relative mode, or 12.26002-1.59801 (-10.66201mm) if in absolute mode. 

This is no problem  in relative/absolute mode, but with missing retraction.  This bug causes serious problems in prints: when nozzle is moved over already printed part without retraction, some amount of filament leak (or rather is sucked out) from nozzle and glued into printed part, so when next perimeter is printed there is not enough filament in nozzle and beginning of perimeter is missing. In my print it causes visible gap in perimeter.  

 

Posted : 09/05/2021 5:54 am
Neophyl
(@neophyl)
Famed Member
RE: BUG in GCODE: Missing retraction in some movements

Fuchsr is quite correct, this is not the place for bug reports.  Its a user to user forum and the Dev's rarely visit here.  You need to open an issue on the prusa slicer github located at https://github.com/prusa3d/PrusaSlicer/issues?q=is%3Aissue+is%3Aopen+sort%3Aupdated-desc   

Don't forget to include a copy of your saved 3mf project file (zipped up into an archive) as well as a clear concise description of the issue as well as all the other information requested when opening an issue.

Posted : 09/05/2021 10:17 am
Zbig
 Zbig
(@zbig)
New Member
Topic starter answered:
RE: BUG in GCODE: Missing retraction in some movements

I've already reported it on github.

Btw. You may control retraction by option: [x] Only retract when crossing perimeters.

When unchecked retraction is triggered always and problem disappears.

(the question is: moving nozzle over existing perimeter should be trated as crossing perimeter or not?) 

Posted : 09/05/2021 7:23 pm
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