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First Layer problem & shrinking

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Hi :grin:


I need some expert advice...


its the first week with my UM2 & i try to improve the quality of some test print...

there is some "gap" problem at some place in the first layer as you can see in the photos :


Photo 26.02.14 21 06 54

Photo 26.02.14 21 07 41

Photo 26.02.14 08 56 48

Photo 26.02.14 08 56 33


Maybe a bed leveling issue ? :/



at the begining of each print i reduce the speed to 20mm/s for the first layer & set the temperature between 230-240°.


i have read that for reduce the shriking i need to low the temperature...i will test that but before i want to avoid the "gap" problem.


what's the best retraction setting for this kind of job ?


it seems difficult to have a completely clean flat surface for the first layer :???:


here's my setting :



layer_height = 0.1

wall_thickness = 0.4

retraction_enable = True

solid_layer_thickness = 0.6

fill_density = 20

nozzle_size = 0.4

print_speed = 50

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

wipe_tower = False

wipe_tower_volume = 15

ooze_shield = False

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 = 0.02

bottom_thickness = 0.2

object_sink = 0

overlap_dual = 0.15

travel_speed = 200

bottom_layer_speed = 20

infill_speed = 0.0

cool_min_layer_time = 5

fan_enabled = True

skirt_line_count = 0

skirt_gap = 3.0

skirt_minimal_length = 150.0

fan_full_height = 0.5

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 = 15

support_xy_distance = 0.7

support_z_distance = 0.15

spiralize = False

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 = True

fix_horrible_union_all_type_b = False

fix_horrible_use_open_bits = False

fix_horrible_extensive_stitching = False

plugin_config =

object_center_x = -1

object_center_y = -1


thanks in advance


(sorry for my bad english, i am swiss :eek: )



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It looks like underextrusion caused by the extruder missing steps. This is very common on the first layer.

The extruder motor has a low amount of electric current going to it (on purpose) so that if the pressure gets too high (about 5Kg) it skips back a bit instead of grinding the plastic to powder.

This only happens on the first layer (likely) because your levelling isn't perfect. Your first layer is probably about 20 to 50% too close.

Most people take care of this by printing the first layer thicker - e.g. .3mm. You have it set to .2mm which is already thicker than your remaining layer height - good start.

I would re-level your bed but level it slightly higher (.05mm higher).

Alternatively you could reduce flow for the first layer to about 70% and then put back on 100% for the second layer.

When you print it's good to watch the extruder motor turning - when it skips it makes a distinctive sound - similar to the sound when you change Z to the next layer - but different.


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I don't see the "gap" in the red photos.

Did you print a skirt around this part? I recommend at least 1 complete skirt to get the filament to start flowing correctly.

we do not see him too much because the other layer is partially clog the hole:

here is it is during the first layer :

Photo 25.02.14 20 03 16

Yes i use the skirt option for the pink one, but i have disable it for the green because it made a diagonal line in the middle of the cover.

What is the "shrinking" problem?

the kind of small "hair" due to the retraction I presume :-|


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