Fillament jamming on support printing (something with retraction)

Hello.

I am skilled CNC programmer for milling and Lathe machines, but fairly new to 3d printing, it's software and Slic3r it self. I tried CURA, I liked it, it almost fits my needs, but Slic3r looks more interesting and promising.

Unfortunately I'm stuck with it. It always jamming filament (s I understand, it's all about filament retraction). By default (for my delta printer) Slic3r and CURA sets 4.5mm at 40mm/s retraction, it's to much, it's jamming as soon as printer ends first continuous line and retracts, that's it, next second extruder can't push filament any more. I managed how to fix this in CURA - 2mm retraction at 20mm/s speed (I think I need a little more, but at least I can print). Now if I make program in CURA - I am sure, it will print it to the end without jamming, a bit dirty, but 100% printed model.

Now for Slic3r:
I set same settings, 2mm retraction at 20mm/s, but printer can't finish even second layer. I have looked into the code, and was surprised to see, that before it goes to the next layer it pushes filament forth a lot(he calls it "retract"), and then again to fixed measure E4.81056(which now calls "unretract"). Here is the sample (highlighted interesting part):

; generated by Slic3r 1.2.9 on 2016-02-27 at 13:41:53

; external perimeters extrusion width = 0.40mm
; perimeters extrusion width = 0.67mm
; infill extrusion width = 0.67mm
; solid infill extrusion width = 0.67mm
; top infill extrusion width = 0.67mm
; support material extrusion width = 0.40mm

M104 S220 ; set temperature
G28 ; home all axes
M106 S250 ; start heating with fan
G1 Z5 F5000 ; lift nozzle

M109 S220 ; wait for temperature to be reached
G21 ; set units to millimeters
G90 ; use absolute coordinates
M82 ; use absolute distances for extrusion
G92 E0 ; reset extrusion distance
M106 S89.25 ; enable fan
G1 E-4.81056 F1800.00000 ; retract
G92 E0 ; reset extrusion distance
G1 Z0.200 F9000.000 ; lift Z
G1 Z0.300 F9000.000 ; move to next layer (0)
G1 Z0.500 F9000.000 ; lift Z
G1 X-53.607 Y-49.850 F9000.000 ; move to first skirt point
G1 Z0.300 F9000.000 ; restore layer Z
G1 E4.81056 F1800.00000 ; unretract
G1 X-53.607 Y-50.000 E4.83467 F1200.000 ; skirt
G1 X-53.212 Y-51.640 E5.10572 ; skirt
G1 X-52.115 Y-52.921 E5.37677 ; skirt

 ; skipped useless skirt code

G1 X-53.071 Y-49.850 F9000.000 ; move to first skirt point
G1 X-53.071 Y-50.000 E72.69696 F1200.000 ; skirt
G1 X-52.678 Y-51.504 E72.94677 ; skirt

 ; skipped again

G1 X-52.536 Y-49.790 E206.79745 ; skirt
G1 E201.98688 F1800.00000 ; retract                                     - What?
G92 E0 ; reset extrusion distance
G1 Z0.500 F9000.000 ; lift Z
G1 X-49.586 Y-49.586 F9000.000 ; move to first perimeter point
G1 Z0.300 F9000.000 ; restore layer Z
G1 E4.81056 F1800.00000 ; unretract
G1 X-49.293 Y-49.647 E4.85861 F1200.000 ; perimeter
G1 X49.293 Y-49.647 E20.70002 ; perimeter

 ; skipped useless perimeter code

G1 X-49.586 Y-49.586 E68.56056 ; perimeter
G1 E63.74999 F1800.00000 ; retract                                                - again?
G92 E0 ; reset extrusion distance
G1 Z0.500 F9000.000 ; lift Z
G1 X-48.785 Y-47.664 F9000.000 ; move to first support material point
G1 Z0.300 F9000.000 ; restore layer Z
G1 E4.81056 F1800.00000 ; unretract
G1 X-48.187 Y-48.857 E5.02491 F1200.000 ; support material

 ; skipped again

G1 X47.828 Y48.857 E1465.87304 ; support material
M104 S215 ; set temperature
G1 E1461.06248 F1800.00000 ; retract                                       - now that's odd!!!
G92 E0 ; reset extrusion distance
G1 Z0.500 F9000.000 ; lift Z
G1 X48.693 Y48.693 F9000.000 ; move to first support material point
G1 Z0.400 F9000.000 ; restore layer Z
G1 E4.81056 F1800.00000 ; unretract
G1 X48.693 Y-48.693 E8.49704 F2400.000 ; support material
G1 X-48.693 Y-48.693 E12.18352 ; support material
G1 X-48.693 Y48.693 E15.87000 ; support material
G1 X48.693 Y48.693 E19.55648 ; support material
G1 X48.315 Y48.058 F9000.000 ; move to first support material point
G1 X47.536 Y46.708 E19.61546 F2400.000 ; support material
G1 X42.299 Y46.708 E19.81371 ; support material

 ; skipped useless support material code

G1 X48.315 Y-47.798 E133.49425 ; support material
G1 E128.68369 F1800.00000 ; retract                         - again
G92 E0 ; reset extrusion distance
G1 Z0.600 F9000.000 ; lift Z
G1 X-49.800 Y-49.800 F9000.000 ; move to first perimeter point
G1 Z0.500 F9000.000 ; restore layer Z
G1 E4.81056 F1800.00000 ; unretract
G1 X49.800 Y-49.800 E11.92359 F1272.119 ; perimeter

Now, most strange part is in this line: G1 E1461.06248 F1800.00000 ; retract
Maybe I am wrong, but... What is this? Is this normal? Where it goes from? How can I fix this?

Please, anyone, help!!! I tried to delete all settings, set up Slic3r again, but no matter, what settings I set for retraction, it always produces the code, which jamming extruder.

If the nozzle is 0.4mm diameter, I'd force slic3r to use wider line widths for the support material and the outer perimeters. You should never try to extrude a line that is narrower than the extruder nozzle. The slic3r people say line width should be between 5% and 70% larger than the nozzle diameter. Do you use a Bowden type extruder or direct? Bowden type require longer retraction distances than direct. I typically use 3000 mm/sec^2 acceleration for retraction, 30mm/sec, and 0.5-1 mm retraction distance when printing ABS with my direct extruder. Make sure the pinchwheel tension on the extruder is very high so the drive gear teeth bite deeply into the filament. If the hot-end jams, the extruder motor should skip steps, not chew a divot into the filament. Make sure you are printing at a high enough temperature. 220C is a little low for ABS.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Those are not the same settings. The Slic3r code is a roughly 5mm retract at 30mm/s. That could be a big problem if your hot end doesn't like long or fast retracts (v6?). You also have Slic3r configured to use absolute distances for extrusion, so each distance it commands is relative to the extruder position the last time it commanded a G92 E0 reset to zero, not relative to zero for that particular commanded extrusion. If for some reason you're using a firmware that doesn't respect the M82 command or has a bug in its implementation, that could be a problem. It wouldn't hurt to try the absolute/relative extrusion toggle in Slic3r, but that's probably not it.

Do check that all your other settings are consistent. If temperature is different that would make a difference. Another potential difference is your z-hop. If that's not configured in Cura, your Slic3r settings are resulting in a longer time with no extrusion going through, which could exacerbate heat-creep issues if your hot-end cooling isn't up to snuff.

Edited 2 time(s). Last edit at 02/27/2016 12:19PM by IMBoring25.

OK, My program was a simple cube without bottom, with 1mm wall thickness (no problem with narrow walls), printing with PLA. The program should fill the whole volume with support (honeycomb) 4mm cell space. My nozzle is 0.4mm and yes, it's a bowden extruder. e3d hot end. 1.75mm filament.

But I think it doesn't matter, because my settings for retraction set to 2 mm, and as I see in the code, it retracts for 4.81056mm. Thank you IMBoring25, I missed that M82 command, silly me. But, again, the problem is that it retracts to much (not as I set)

The feeding of material is ok, I think, it doesn't look different then with CURA, I think I shouldn't change anything here. Feed rates and temperature adjusting - maybe, but I set everything as in CURA, and everything should be fine, no?

Main difference I see between Cura and Slic3d is that Cura tries to make everything in one continuous line, and Slic3d moves more chaotic, permanently starting new lines, and as a result - it constantly retracts filament. And here we go again, retracts to much, filament gets stuck, viola.

I need to figure, what makes Slic3r retract at 4.81056mm?

That fits. I'm not familiar with the older ones, but the E3D v6 definitely doesn't like that much retract, especially with PLA (and 220 is pretty hot for PLA, too, which would exacerbate the issue).

At the bottom of the gcode file Slic3r adds a long string of comments defining the values of all the configuration variables that were used in the slicing. Could you post that section?

Attached full file.

After that I tried to turn off retract on layer change, set retract to 0mm, then set to 10mm, but still, it always retracts to 4.8 mm.

By the way, why there is no C0, G2, G3 or G10 in the code? Any figure I try, movement is always G1Fsomething, and retract is G1Esomething? But this is for another topic.

Problem seems to be solved (at least gone for me). I removed old config (again), set up a new printer, Marlin firmware, circular bed shape, so on, as always. And now, the default settings for retraction is 2 mm. That's strange, because before that it was always about 4.5mm (something around). What caused before Slic3r to set different default settings - I don't know. Any Ideas?

Now I sliced again same model with new default settings (only added support). Now I see right retraction in the code. (can't start printing to check for now, a little later)

Next, changed retraction to 4mm, sliced again, the code changed, ok.

Then changed back to 2 mm, restarted Slic3r, everything ok.

Switched to Expert mode, changed support to honeycomb, the code looks ok.

In Expert mode changed retraction back and forth, restarted few times, the mysterious 4.81056 has gone.

Solved. Thanks to everyone, who tried to help.

Edited 1 time(s). Last edit at 02/28/2016 03:37AM by Kostolapy.

G0 is treated the same as G1 in the reprap implementation.

G2 and G3 are supported in some firmwares but not any slicers of which I'm aware. It would take some interpolation since the input files are STLs, which inherently segment curves.

G10 varies. It only does something like what you're expecting if you're running RepRapFirmware, MachineKit, or the RepRapPro branch of Marlin. Otherwise it may command a firmware retraction. Tool offsets are generally considered set-and-forget items configured in firmware and/or EEPROM. I do have G10s in my start gcode for my RepRapFirmware machine, to establish active and standby temperatures.

[reprap.org]