Retraction settings

[reeper 0]

I’ve been out of printing commission for a while but am happy to have found the time to tinker once more.

 

I have wanted to test out retraction so I decided to attack the klein bottle (http://www.thingiverse.com/thing:2273 without scaling)

In terms of setup I have a late 2011 ultimaker fitted with a v3 bolt, the spring extruder drive upgrade, the extruder clip and a v1 hot end(I have the v2 upgrade but haven’t had any obvious issues with the first version thus far).

My ultimaker is running the latest Marlin firmware from github in order to avoid the retraction bug that Illuminarti mentions here http://umforum.ultimaker.com/index.php?/topic/1789-retraction-and-blobs/?hl=retraction

Using cura 13.03 and the following settings, my first attempt(Print 1) failed when the print head knocked it over before the print could finish(5 hours into the print :( ). Given that the initial layer was extremely small, I assume that a slight bit of warped PLA catching the print head was enough to dislodge the print.

Print 1 settings :

 

filament_diameter = 3.00

nozzle_size = 0.4

wall_thickness = 0.8

retraction_enable = True

layer_height = 0.1

solid_layer_thickness = 0.6

fill_density = 20

print_speed = 50

print_temperature = 200

support = None

enable_raft = False

filament_density = 1.00

skirt_line_count = 3

skirt_gap = 3.0

retraction_min_travel = 3.0

retraction_speed = 30.0

retraction_amount = 4.0

retraction_extra = 0.0

travel_speed = 200

max_z_speed = 3.0

bottom_layer_speed = 20

cool_min_layer_time = 5

fan_enabled = True

bottom_thickness = 0.3

object_sink = 0.0

enable_skin = False

plugin_config = (lp1

.

model_matrix = 1.0,0.0,0.0,0.0,1.0,0.0,0.0,0.0,1.0

extra_base_wall_thickness = 0.0

cool_min_feedrate = 10

fan_layer = 1

fan_speed = 100

fan_speed_max = 100

raft_margin = 5

raft_base_material_amount = 100

raft_interface_material_amount = 100

support_rate = 50

support_distance = 0.5

infill_type = Line

solid_top = True

fill_overlap = 15

bridge_speed = 100

sequence = Loops > Perimeter > Infill

force_first_layer_sequence = True

joris = False

retract_on_jumps_only = True

hop_on_move = False

 

 

I decided that the retraction of the first print wasn’t aggressive enough, so I conservatively extended the retraction amount by 0.5mm to 4.5mm for the second print. I also sunk the object by 3 mm to improve bed adhesion and avoid the bottle being knocked over a second time.

As can be seen in the image, the second print finished but the retraction actually appears to be worse than in the first. I checked the filament diameter and it doesn’t appear to have increased so I’m at a loss as to why it has worsened.

I would also appreciate any advice on handling the overhangs in this print, I suppose a different fan duct or a second fan would improve matters ?

 

[gr5 1,971]

You have "stringing". The simplest thing to do to reduce stringing is to lower temperature:

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

But be careful - you are already pretty low at 200C. I strongly recommend you do a simple test like the one I did in the above post as all PLAs are not the same both manufacturer and color. I'm told it helps to have a good quality PLA.

If you lower the temperature more you might get underextrusion which would mean you would have to lower the speed also although 50mm/sec would be plenty slow enough for me at 190C (100mm/sec would be a bit too fast for my grape colored PLA). This is also addressed at the above link.

Also you might want to add a clip: There's a blue clip on the print head where the bowden tube connects. You might want to make a similar one on the feeder. Other people seem to think this helps reduce how much you have to retract. I have one and 4.5mm is plenty for me.

Also 40mm/sec might be too fast for the retraction speed with the latest Marlin. I'm not sure - there's been discussion about this lately but I don't have the latest marlin so I haven't touched that setting.

But really I suspect the only thing you need to do is lower temp by 10C but don't waste another hour on this - do a test print first.

 

[gr5 1,971]

Oh - and to get better adhesion to the blue tape, wash it once with Isopropyl alcohol (aka rubbing alcohol) - found at any drugstore that sells aspirin and bandages. If you do that you shouldn't need to sink the bottle by 3mm.