Odd fill/missing layers below solid pillars #39

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rtgoodwin opened this Issue Nov 9, 2011 · 13 comments

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Model here: http://www.thingiverse.com/thing:13408

Model prints mostly fine (way better than SF :) ), but below each pillar for 1 or 2 layers there is space left in in the infill. It actually tries to print the outlines of the columns as if they are inset into the model versus starting at the surface layer. Similar thing happens with Hollow Pyramid Short on thingiverse.

This is 11/4 build!

I'm seeing this as well with the Hollow Calibration Pyramid (http://www.thingiverse.com/thing:11846). It almost seems like the logic for determining infill is taking precedence over the logic for making bottom layers solid. So it ends up carving out an area of the otherwise solid layers and making it non-solid.

Owner

alexrj commented Nov 10, 2011

Can you please post a screenshot of the wrong layer(s)?
You can preview the print from Pronterface: load the file and click on the preview window; there you can view all layers.

Here you go: http://www.newdiversions.com/skimages//pyramid_layer_issue-20111110-095424.jpg . You can see the "hole" left for the pillar before it starts, this lasts a couple of layers.

Sorry that's of the pyramid from Pointedstick, here's the original model with the round pillars: http://www.newdiversions.com/skimages//retract_model_layers-20111110-095700.jpg

The pyramid thing there is exactly what I see as well.

Please post your config.ini and also any command-line arguments used.

bottom_layer_speed_ratio = 0.3
duplicate_distance = 6
duplicate_x = 1
duplicate_y = 1
end_gcode = M84 ; disable motors
filament_diameter = 1.76
filament_packing_density = 1.056
fill_angle = 0
fill_density = 0.1
infill_every_layers = 1
layer_height = 0.2
nozzle_diameter = 0.35
perimeter_feed_rate = 30
perimeter_offsets = 3
print_center = 60,60
print_feed_rate = 45
retract_before_travel = 2
retract_length = 1
retract_lift = 0
retract_restart_extra = 0
retract_speed = 18
rotate = 0
scale = 1
skirt_distance = 6
skirts = 3
solid_layers = 3
start_gcode = G92 X0 Y0 Z0 E0 ; reset distance
temperature = 185
travel_feed_rate = 100
use_relative_e_distances = 0
z_offset = 0

Owner

alexrj commented Nov 13, 2011

This might be fixed (I didn't test it). Can you test it with current git or new packages once they're out? Thank you! :)

As of git last night, a Buddha I printed had gaps in the solid base
before the body. Will grab more details!

On Nov 13, 2011, at 2:31 PM, Alessandro Ranellucci
reply@reply.github.com
wrote:

This might be fixed (I didn't test it). Can you test it with current git or new packages once they're out? Thank you! :)


Reply to this email directly or view it on GitHub:
#39 (comment)

Here [1] is an illustration of the pattern that is breaking the "retract test.STL" object. The in-fill is somehow breaking into the solid-layers. The illustration was made with today's Slic3r (20111114) using 100% default settings.

[1] http://dallasmakerspace.org/w/images/a/aa/Retract-test-bug.jpg

Owner

alexrj commented Nov 15, 2011

Hello Peter, thank you for the excellent screenshot. That helped me much.
I regret to say that it's not a bug but an intended behaviour: those areas in layers 2 and 3 are not given a solid infill because they're internal areas (no top, no bottom). The solid infill is only drawn in the areas that are actually exposed to open air: those areas below the pillars are not exposed to open air. Let me know if my explanation wasn't clear enough.

That said, we could have encountered a situation (pillars/small areas) where this behaviour is dangerous for the quality of the print. While it makes sense for most of cases, you're making me think about handling this particular situation as an exception.

My question is: does this impact print quality?
Do you have pictures of bad results?

If so, the solution is to detect these situations (small internal surfaces inside solid surfaces) and merge them in order to have a single solid surface. (Note to self: small could be defined as those surfaces which cannot be offsetted by the number of perimeters + n.)

I would have to say that it does affect the quality and strength of the
print. For example, in this case, the first layer of the column, i.e. the
first "hollow circle" that gets laid down I observed is not uniform, as it
almost acts like a bridge layer without a completely solid surface to stick
to. I noticed for example 2 or 3 of the pillars had deformed circles (flat
sides, etc). They "catch up" as the pillars build, but you are left with
exposed areas around the bases from not being a flush fit. (Compare this to
SF where it is a clean, flush fit around the bases of the pillars).

Does this relate to the "buddha bug", because it looks very similar in the
resulting print, i.e. there is open space around the first "smaller" layer
(the pillar, or in the case of buddha the beginning of his body) where it
should be solid? One can basically "see" into the infill.

So, based on visual quality alone, I would say it remains something that
should probably be addressed, if for no other reason than aesthetically it
looks wrong, but may have impact on strength/quality of bond/parts, and so
far a lot of the user base keeps bringing it up as a bug :)

Thoughts? Hope to be around IRC later as well.

On Tue, Nov 15, 2011 at 3:34 AM, Alessandro Ranellucci <
reply@reply.github.com

wrote:

Hello Peter, thank you for the excellent screenshot. That helped me much.
I regret to say that it's not a bug but an intended behaviour: those
areas in layers 2 and 3 are not given a solid infill because they're
internal areas (no top, no bottom). The solid infill is only drawn in the
areas that are actually exposed to open air: those areas below the pillars
are not exposed to open air. Let me know if my explanation wasn't clear
enough.

That said, we could have encountered a situation (pillars/small areas)
where this behaviour is dangerous for the quality of the print. While it
makes sense for most of cases, you're making me think about handling this
particular situation as an exception.

My question is: does this impact print quality?
Do you have pictures of bad results?

If so, the solution is to detect these situations (small internal
surfaces inside solid surfaces) and merge them in order to have a single
solid surface. (Note to self: small could be defined as those surfaces
which cannot be offsetted by the number of perimeters + n.)


Reply to this email directly or view it on GitHub:
#39 (comment)

@alexrj alexrj added a commit that referenced this issue Nov 16, 2011

@alexrj alexrj Print solid infill without cutting an internal surface under small re…
…gions such as pillars. #39
8aca717
Owner

alexrj commented Nov 16, 2011

Done!

alexrj closed this Nov 16, 2011

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