Change_layer without retract produces cleaner edges

[canadaduane]

I find that whenever the layer changes, the automatic retract is unnecessary, and in fact produces a poorer quality output. By commenting out the following line in change_layer, I get less oozing near corners and edges (i.e. whenever the layer changes):

$gcode .= $self->retract(move_z => $z);

Why was this introduced there in the first place?

[koolatron]

Maybe this should be made optional?

[canadaduane]

Optional would be fine. I kept increasing the retract-before-travel distance until it was obvious that the value was being completely ignored in some retract scenarios. That's how I eventually tracked it down to that line. Being able to switch it off would be helpful.

[alranel]

Can you please provide your config.ini?

[canadaduane]

Sure, here it is:

bottom_layer_speed_ratio = 0.2
bridge_flow_ratio = 1
bridge_speed = 120
duplicate_distance = 6
duplicate_x = 1
duplicate_y = 1
end_gcode = M104 S0 ; turn off temperature\nG91 ; rel movement\nG1 F1800 E-5 retract;\nG1 Z+30 ; move Z up a bit and retract filament by 5mm\nG28 X0  ; home X axis\nM84     ; disable motors\nM107 ; turn fan off
extrusion_axis = E
extrusion_multiplier = 1.06
extrusion_width_ratio = 0
filament_diameter = 3
fill_angle = 30
fill_density = 0.4
fill_pattern = rectilinear
first_layer_height_ratio = 0.5
g0 = 0
gcode_arcs = 0
infill_every_layers = 1
infill_speed = 120
layer_height = 0.2
nozzle_diameter = 0.3
overlap_ratio = 0.15
perimeter_speed = 80
perimeters = 2
print_center = 100,100
retract_before_travel = 2
retract_length = 3
retract_lift = 0
retract_restart_extra = 0
retract_speed = 30
rotate = 0
scale = 1
skirt_distance = 12
skirt_height = 1
skirts = 1
small_perimeter_speed = 80
solid_fill_pattern = rectilinear
solid_infill_speed = 120
solid_layers = 2
start_gcode = M92 X78.7402 Y78.7402 E926\nG28 ; home all axes\nM106 ; turn fan on
temperature = 225
travel_speed = 250
use_relative_e_distances = 0
z_offset = 0

[alranel]

With this config, layer change is not happening on the edges. It will happen on the last point if the infill, which is an internal point. This is the sequence:

• finish infill
• retract
• move Z
• move to XY position (which is an internal perimeter, not a visible part)
• compensate retraction
• start the internal perimeter

Thus I don't get how the retraction would affect quality of exterior parts, since it's always happening in internal points. I'm getting very clean parts with my setup. Can you give some insight on this? Maybe pictures, videos of whatever.

[canadaduane]

I'm trying to figure out how to get more details to you. I wish I had a camera here. The basic problem seems to be that there is a little pool of plastic extruded whenever a retract occurs. It's quite small, and mostly unnoticeable, except when it's on the edge. In that case (and especially when a bunch of these line up layer after layer) the spillover gets pretty bad. I will try to find a camera to explain further.

[alranel]

Did you try adjusting the Retract Extra Distance by setting it to a negative value? What hot-end do you have?

[canadaduane]

0.4 mm Ultimaker hot end. I'm not sure if they have version numbers like the MakerBot (MK7 or whatever). I'm fairly new to all of this :) Are there any specific specs your looking for in describing the hot end?

I gave the negative Retract Extra Distance a try, but it didn't seem to help. Thanks for the suggestions though. I will provide more information when I have it. Closing issue for now (I will be away for the next 2 weeks).