Triangle mesh slicing bug

[workshopninja]

Prusa Edition - 1.39.1

MacOS 10.10.5

My STL files seem clean in the 3D render but some holes have a layer put on top in the gcode preview.

config.ini.zip
InsideCornerBracketM5x3.stl.zip

UPDATE:

When I rotate the model using the 45° buttons and re-slice, the problem moves to different holes!
There IS a position which does not cap the holes.

replicated in prusa edition 1.38.5

[wabbitguy]

I just tested it in OS X 10.13.3 using Prusa 1.39.1... took me a while to find what makes the problem appear. Change your first layer height to .21 from the .2 you have it set it. It slices fine when I did that.

[workshopninja]

Sweet, Thanks a lot. Isaac gollan workshopninja@gmail.com

…

On Apr 11, 2018, at 11:50, wabbitguy ***@***.***> wrote: I just tested it in OS X 10.13.3 using Prusa 1.39.1... took me a while to find what makes the problem appear. Change your first layer height to .21 from the .2 you have it set it. It slices fine when I did that. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub, or mute the thread.

[bubnikv]

@FidelCapo Would you please retest with 1.40-alpha and if it works close this issue? Thanks.

[wabbitguy]

@bubnikv I just tested with the 1.40-alpha and where the layer height and the first layer height are both .2 for that corner bracket design with the users original config.

It fills in the top of the horizontal bracket through holes.

Change either the first layer height or the layer height and it works fine.

[bubnikv]

I will need to dig deeper, but it looks like Slic3r has issues when slicing the triangle mesh at a height, where the slicing plane cuts across a plane in the model exactly or very, very closely. That explains why changing the layer height just a little fixes this issue.

[workshopninja]

Can I just say thank you for the work that you do - blows my mind this is free. Isaac gollan workshopninja@gmail.com

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On May 16, 2018, at 02:25, bubnikv ***@***.***> wrote: I will need to dig deeper, but it looks like Slic3r has issues when slicing the triangle mesh at a height, where the slicing plane cuts across a plane in the model exactly or very, very closely. That explains why changing the layer height just a little fixes this issue. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub, or mute the thread.

[bubnikv]

I just checked with the latest Slic3r 1.41.0-beta. It seems that in this case Slic3r may not be guilty, but your modeler. I suppose there are really zero thickness layers closing the top of the holes, also there are the same zero thickness membranes, which are then sliced as on the next screen shot. These kind of errors happen if one subtracts one cylinder from the other in a dumb CAD system, and the front and back planes of the two cylinders overlap exactly The dumber CADs then leave a thin membrane on both sides of the bigger cylinder.

After fixing your model with NetFabb (now integrated in Slic3r on Windows 10), the problem goes away.

[bubnikv]

Which CAD did you model with? Could you create another STL by subtracting longer "drilling" cylinders?

[bubnikv]

Fixed with 1.41.1-beta.