Pressure advance bug(?) fails print instantly

Hello there,

i've encountered a bug recently which made my 3DBenchy testprint failing almost instantly at a certain point. But lets start with in the beginning. I've spent literally countless hours calibrating my Kossel Mini and finding the best settings whithin Slic3r. For now I've found nearly perfect print settings (at least for my expectations). I have done some prints with those settings which all were fantastic. Especially the pressure advance settings made some great improvements on my prints. I've tested the setting after reading this thread [github.com]. I made some test prints to evaluate the best setting for the pressure advance setting like llluis does in his post from the thread mentioned before. The best print quality with perimeters and infill I got with pressure advance set to 0.15. Until now I never had any problems with pressure advance. To better clarify my problem I cut the specific part of the gcode where the "bug" happened (see below).

I printed this thing: [www.thingiverse.com]

I could list all my settings but for now I just say that my pressure advance is set to 0.15 and my retraction settings are as following:
Length = 2mm
Lift Z = 0
Speed = 40mm/s
Extra length on restart = 0
minimum travel after retraction = 2mm
retract on layer change yes
wipe while retracting no

G-Code passage where the "bug" happend (specific parts highlighted):
G1 X19.947 Y-9.243 F4800.000
G1 E2.00000 F2400.00000
G1 E2.16414 F2400.000 ; pressure advance // Remark: usual pressure advance, 0.16mm advance, matches settings
G92 E2.00000 ; restore E
G1 X19.596 Y-9.550 E2.02439 F1200.000
G1 X19.284 Y-9.904 E2.04901
G1 X19.227 Y-9.944 E2.05265
G1 X18.398 Y-10.436 E2.10299
G1 X17.517 Y-10.926 E2.15567
G1 X16.464 Y-11.469 E2.21758
G1 X15.535 Y-11.911 E2.27133
G1 E2.10719 F2400.000 ; pressure discharge // Remark: usual pressure discharge, 0.17mm discharge, matches settings
G92 E2.27133 ; restore E
G1 E0.27133 F2400.00000
G92 E0
G1 X15.528 Y-11.972 F4800.000
G1 X24.847 Y5.395 F4800.000
G1 X24.833 Y5.393 F4800.000
G1 E2.00000 F2400.00000
M106 S255
G1 E24.42170 F2400.000 ; pressure advance // Remark: Nearly 23mm filament advance
G92 E2.00000 ; restore E
G1 X24.593 Y5.192 E2.06379 F3600.000
G1 X24.023 Y5.810 E2.23499
G1 X24.264 Y6.012 E2.29898
M106 S206.55
G1 X19.948 Y9.242 F4800.000
G1 E-19.95889 F2400.000 ; pressure advance // Remark: ~20mm retraction
G92 E2.29898 ; restore E
G1 X19.595 Y9.550 E2.32346 F1200.000

Picture from gcode explorer on the place where the bug happend:


Picture of the hole on the side where the bug happened (huge drop of filament):


Picture of the hole on the side which is printed correctly:



As you can see the print clearly fails there because of the wrong calculations of the pressure advance. The worst thing about this is that I have an bowden extruder with an e3dv6 hotend and with those huge retractions (about ~20mm as you can see in the gcode above) the hotend instantly cloggs. To finish the print above I had to pause immediatly, push out the bowden tube and remove the clogged filament from above which was stuck on the entry of the nozzel. Afterwards I could resume the print but that layer is clearly damaged and visible on the print.

Maybe you could help me figuring out what I am doing wrong here. Maybe it's a problem within slic3r itself, I dont know

Regards
Sebastian

Edited 1 time(s). Last edit at 01/29/2016 04:08PM by Heesh.