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jamboy

UM2 - retraction doesn't work well with cura

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Hello Together,

i've testet it several times, but the retraction on the UM2 with cura doesn't work nice.

When the print starts, you hear the retractions. After some layers, the printer stops to retract and the stringing begins. (you here it from the step motor)

I testet it with some different parts, but on every part were stringing. Changed the settings for temperature / travel speed and the retractions settings, but non wore working fine.

Also the support structure strings really much, i think this was a problem some cura version before?

Get anybody a nice print with retraction from the Ultimaker 2?

I have the feeling that cura got some really strange slicing methods. You got for example a circle or something and the printhead moves right in the middle through the circle.

Ive printed these with no success:

http://www.thingiverse.com/thing:104120

http://www.thingiverse.com/thing:12105

http://www.thingiverse.com/thing:113764 (support stucture stringing)

With all prints retraction was enabled. The best result with ultimaker PLA was with retraction length: 5,5

retraction speed: 25 mm/s (maximum)

http://imageshack.us/photo/my-images/853/zrv1.jpg/

http://imageshack.us/photo/my-images/41/qtjw.jpg/

http://imageshack.us/photo/my-images/203/kufw.jpg/

Thanks in advance for your feedback.

 

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I think this is a cura issue, not a UM2 issue.

1) The square (squarish) vase. There are 4 STL files. Which one did you use? Normally I would recommend one of the first 2 and tell you to uncheck the "solid infill top". Is this what you did? Be aware that if you do this there will be ZERO retraction because Cura doesn't retract *inside* prints. So you if you want retraction to work, instead use "thickwall" or "3mm wall".

2) You shouldn't have this issue with this other "stratum" vase. In Cura, after it slices, look at the vase in layer view. Layer view shows a blue line for non-extruding moves but for retraction it additionally shows a short vertical line segment. Look for those to see if Cura is in fact doing retraction. It probably *is* doing retraction but if not, show us a screen shot of Cura where you think it should be retracting yet it isn't.

3) Even with retraction occurring, you can still get strining. Try printing MUCH slower. Try 1/3 the speed you are printing now. Also try as low a temp as you can go. Maybe 190C. Or maybe that is too cold for your filament. Both slowing down and cooler temperatures -- these both reduce stringing -- see first photo here:

http://umforum.ultimaker.com/index.php?/topic/1872-some-calibration-photographs/

 

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Thanks for your post. Yes i think also that this is a cura failure.

1) yes i used the second one. No i redesigned it and cut off the top, and exported it again as stl.

2) i will test it tomorrow and give you a feedack.

3) with the original ultimaker pla i can go down to 215. With 210 the lines will not stick nice together so i need to go up to 215. I tested it with 60mm/s, should i go down there.

Thanks.

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@jamboy - that picture is fuzzy but I can clearly see at least one retraction indicator - it's those short blue lines that go straight up vertically. Could you give a second screenshot but at a better angle so we can see the vertical lines? The one around "1 o'clock" looks good and I think there is one around "9 O'Clock" that also looks good. It's very hard to tell in this image.

It looks like maybe it is only retracting on *some* of the lines and not others but I'm not sure mostly because of the angle. Do you have "combing" enabled? Can you just also save your profile and post the entire ini file as text? But more importantly post another screenshot with a better angle.

 

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Hey Gr5, thanks for your time.

Attached the screenshots. I changed not much, only some basic settings, the rest is original UM2 settings.

The speed i change at the controller to 60 %.

http://img823.imageshack.us/img823/7070/qyu8.jpg

Sorry the picture is also not better. I was thinking with all blue lines, the um2 should retract?

Here the screenshot of the "square" vase:

http://img819.imageshack.us/img819/7154/4osp.jpg

Why are here the blue lines? Exactly there the UM2 fill the lines with material (stringing)

[profile]

layer_height = 0,2

wall_thickness = 0,8

retraction_enable = True

solid_layer_thickness = 0,6

fill_density = 10

nozzle_size = 0.4

print_speed = 100

print_temperature = 220

print_temperature2 = 0

print_temperature3 = 0

print_temperature4 = 0

print_bed_temperature = 70

support = None

platform_adhesion = None

support_dual_extrusion = Both

filament_diameter = 2.85

filament_diameter2 = 0

filament_diameter3 = 0

filament_diameter4 = 0

filament_flow = 100.0

retraction_speed = 40.0

retraction_amount = 4.5

retraction_dual_amount = 16.5

retraction_min_travel = 1.5

retraction_combing = True

retraction_minimal_extrusion = 0.5

bottom_thickness = 0.3

object_sink = 0.0

overlap_dual = 0.2

travel_speed = 150

bottom_layer_speed = 20

infill_speed = 0.0

cool_min_layer_time = 5

fan_enabled = True

skirt_line_count = 1

skirt_gap = 3.0

skirt_minimal_length = 150.0

fan_layer = 1

fan_speed = 100

fan_speed_max = 100

cool_min_feedrate = 10

cool_head_lift = False

solid_top = True

solid_bottom = True

fill_overlap = 15

support_fill_rate = 20

support_xy_distance = 0.7

support_z_distance = 0.15

brim_line_count = 20

raft_margin = 5

raft_line_spacing = 1.0

raft_base_thickness = 0.3

raft_base_linewidth = 0.7

raft_interface_thickness = 0.2

raft_interface_linewidth = 0.2

fix_horrible_union_all_type_a = False

fix_horrible_union_all_type_b = False

fix_horrible_use_open_bits = False

fix_horrible_extensive_stitching = False

plugin_config = (lp1

.

object_center_x = -1

object_center_y = -1

[alterations]

start.gcode = ;Sliced at: {day} {date} {time}

;Basic settings: Layer height: {layer_height} Walls: {wall_thickness} Fill: {fill_density}

;Print time: {print_time}

;Filament used: {filament_amount}m {filament_weight}g

;Filament cost: {filament_cost}

G21 ;metric values

G90 ;absolute positioning

M107 ;start with the fan off

G28 X0 Y0 ;move X/Y to min endstops

G28 Z0 ;move Z to min endstops

G1 Z15.0 F{travel_speed} ;move the platform down 15mm

G92 E0 ;zero the extruded length

G1 F200 E3 ;extrude 3mm of feed stock

G92 E0 ;zero the extruded length again

G1 F{travel_speed}

M117 Printing...

end.gcode = ;End GCode

M104 S0 ;extruder heater off

M140 S0 ;heated bed heater off (if you have it)

G91 ;relative positioning

G1 E-1 F300 ;retract the filament a bit before lifting the nozzle, to release some of the pressure

G1 Z+0.5 E-5 X-20 Y-20 F{travel_speed} ;move Z up a bit and retract filament even more

G28 X0 Y0 ;move X/Y to min endstops, so the head is out of the way

M84 ;steppers off

G90 ;absolute positioning

start2.gcode = ;Sliced at: {day} {date} {time}

;Basic settings: Layer height: {layer_height} Walls: {wall_thickness} Fill: {fill_density}

;Print time: {print_time}

;Filament used: {filament_amount}m {filament_weight}g

;Filament cost: {filament_cost}

G21 ;metric values

G90 ;absolute positioning

M107 ;start with the fan off

G28 X0 Y0 ;move X/Y to min endstops

G28 Z0 ;move Z to min endstops

G1 Z15.0 F{travel_speed} ;move the platform down 15mm

T1

G92 E0 ;zero the extruded length

G1 F200 E10 ;extrude 10mm of feed stock

G92 E0 ;zero the extruded length again

G1 F200 E-{retraction_dual_amount}

T0

G92 E0 ;zero the extruded length

G1 F200 E10 ;extrude 10mm of feed stock

G92 E0 ;zero the extruded length again

G1 F{travel_speed}

M117 Printing...

end2.gcode = ;End GCode

M104 T0 S0 ;extruder heater off

M104 T1 S0 ;extruder heater off

M140 S0 ;heated bed heater off (if you have it)

G91 ;relative positioning

G1 E-1 F300 ;retract the filament a bit before lifting the nozzle, to release some of the pressure

G1 Z+0.5 E-5 X-20 Y-20 F{travel_speed} ;move Z up a bit and retract filament even more

G28 X0 Y0 ;move X/Y to min endstops, so the head is out of the way

M84 ;steppers off

G90 ;absolute positioning

support_start.gcode =

support_end.gcode =

cool_start.gcode =

cool_end.gcode =

replace.csv =

switchextruder.gcode = ;Switch between the current extruder and the next extruder, when printing with multiple extruders.

G92 E0

G1 E-36 F5000

G92 E0

T{extruder}

G1 X{new_x} Y{new_y} Z{new_z} F{travel_speed}

G1 E36 F5000

G92 E0

 

 

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retraction_speed = 40.0

retraction_amount = 4.5

retraction_dual_amount = 16.5

retraction_min_travel = 1.5

retraction_combing = True

retraction_minimal_extrusion = 0.5

 

Something is wrong because there is ZERO retraction on those blue lines. If there was you would see a vertical blue line and there isn't one anywhere.

Change "minimum travel" and "minimal extrusion" to zero and that should put the retraction back in. You don't have to print anything to verify this - you should see it in the gcode view (layer view).

 

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It is possible to print with UM1 settings (You'll get a warning that the settings in the machine will be ignored)

And I think it's related to the "minimal extrusion amount", this setting is added to prevent a lot of retraction on a small piece of filament, but it might act a bit different on the UM1 then the UM2 settings.

 

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Hey Daid,

but why is the UM2 then not retracting at all the blue lines? Sometimes it retracts, but not really often at the 2 vases.

When it retracts, it works nice.

I can send you a gcode file of the square vase. About 1000 layers (at 0,1 layer high) and there are only 10 retractions (g10 and g11's).

And that's what it's look like. Retraction was enabled.

http://imageshack.us/photo/my-images/203/kufw.jpg/

GCode file:

http://www.file-upload.net/download-8233654/randomvase.gcode.html

 

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