Slic3r default extrusion width?

Hello,

I’m comparing gcode selected from profiles for 0.30 layer thickness and 0.40 layer thickness and something puzzles me.

I’m slicing the large herringbone gear. For 0.40 the code starts with this:

; generated by Slic3r 0.9.8 on 2013-07-06 at 03:16:28

; layer_height = 0.4
; perimeters = 3
; top_solid_layers = 2
; bottom_solid_layers = 2
; fill_density = 0.75
; perimeter_speed = 40
; infill_speed = 60
; travel_speed = 130
; scale = 1
; nozzle_diameter = 0.5
; filament_diameter = 2.89
; extrusion_multiplier = 1
; perimeters extrusion width = 0.53mm
; infill extrusion width = 0.53mm
; first layer extrusion width = 0.40mm

For 0.30 the code starts with this:

; generated by Slic3r 0.9.8 on 2013-07-06 at 03:30:46

; layer_height = 0.3
; perimeters = 3
; top_solid_layers = 2
; bottom_solid_layers = 2
; fill_density = 0.75
; perimeter_speed = 40
; infill_speed = 60
; travel_speed = 130
; scale = 1
; nozzle_diameter = 0.5
; filament_diameter = 2.89
; extrusion_multiplier = 1
; perimeters extrusion width = 0.70mm
; infill extrusion width = 0.70mm
; first layer extrusion width = 0.45mm

How come the extrusion width is fatter (0.70mm) for my 0.30 profile than for my 0.40 profile? When I compare with this gcode shouldn’t it be 0.36mm instead? :confused:

My config.ini:

# generated by Slic3r 0.9.8 on Sat Jul  6 03:44:58 2013
bed_size = 190,200
bed_temperature = 0
bottom_solid_layers = 2
bridge_fan_speed = 100
bridge_flow_ratio = 1
bridge_speed = 60
brim_width = 0
complete_objects = 0
cooling = 1
default_acceleration = 0
disable_fan_first_layers = 1
duplicate = 1
duplicate_distance = 6
duplicate_grid = 1,1
end_gcode = M104 S0 ; turn off nozzle temperature\nM140 S0 ; turn off bed temperature\nG28 X0  ; home X axis\nM84     ; disable motors
external_perimeter_speed = 100%
extra_perimeters = 1
extruder_clearance_height = 20
extruder_clearance_radius = 20
extruder_offset = 0x0
extrusion_axis = E
extrusion_multiplier = 1
extrusion_width = 0
fan_always_on = 0
fan_below_layer_time = 60
filament_diameter = 2.89
fill_angle = 45
fill_density = 0.75
fill_pattern = line
first_layer_bed_temperature = 0
first_layer_extrusion_width = 150%
first_layer_height = 100%
first_layer_speed = 100%
first_layer_temperature = 0
g0 = 0
gap_fill_speed = 40
gcode_arcs = 0
gcode_comments = 0
gcode_flavor = reprap
infill_acceleration = 0
infill_every_layers = 1
infill_extruder = 1
infill_extrusion_width = 0
infill_speed = 60
layer_gcode = 
layer_height = 0.3
max_fan_speed = 100
min_fan_speed = 35
min_print_speed = 10
min_skirt_length = 0
notes = 
nozzle_diameter = 0.5
only_retract_when_crossing_perimeters = 0
output_filename_format = [input_filename_base].gcode
perimeter_acceleration = 0
perimeter_extruder = 1
perimeter_extrusion_width = 0
perimeter_speed = 40
perimeters = 3
post_process = 
print_center = 95,100
randomize_start = 1
retract_before_travel = 2
retract_length = 1.2
retract_length_toolchange = 3
retract_lift = 0
retract_restart_extra = 0
retract_restart_extra_toolchange = 0
retract_speed = 25
rotate = 0
scale = 1
skirt_distance = 6
skirt_height = 1
skirts = 2
slowdown_below_layer_time = 8
small_perimeter_speed = 40
solid_fill_pattern = rectilinear
solid_infill_below_area = 70
solid_infill_every_layers = 0
solid_infill_speed = 60
start_gcode = G28 ; home all axes
support_material = 0
support_material_angle = 0
support_material_extruder = 1
support_material_extrusion_width = 0
support_material_pattern = rectilinear
support_material_spacing = 2.5
support_material_speed = 60
support_material_threshold = 45
temperature = 0
threads = 2
toolchange_gcode = 
top_solid_infill_speed = 60
top_solid_layers = 2
travel_speed = 130
use_relative_e_distances = 0
vibration_limit = 0
z_offset = 0

Thanks.

I updated Slic3r to 0.9.10b and cleared my old profile. It still produces a fatter extrusion width for a 0.30 thick layer (0.70mm) than for 0.40 (0.53mm).

Still puzzled by this but I’m printing one anyway (in Lulzbot green :smiley: ) to see how it goes.

isn’t that the way it is supposed to go?

if you are extruding the same layer thickness as your nozzle thickness, then the extrusion will be nearly a cylinder, with the same width as your nozzle (0.35mm wide for a 0.35mm layer thickness and nozzle).
and then if you squish that down to get a thinner layer you would be widening the extrusion thickness…wouldn’t you? Like squishing a cylinder flat.

seems to make sense.

I never thought of it that way. It would indeed make sense.

And I forgot the TAZ comes with a 0.35mm nozzle rather than a 0.50 like my AO-100. That would explain why the extrusion width in the g-code I linked was thinner (0.36mm).

Thanks.