Ailerons out of a tapered wall - slicing weirdness

[jgwinner]

I ran into a weird issue slicing a part with a wall that tapers. Cura sliced it fine, making the entire wall two layers wide when it 'tapered'.

S3D, on the other hand, made a weak "Aileron" out of the wall.



versus:



While I could, and did, redesign the part, this seems to be a problem with the slicer. I tried several different options, including specific start locations, everything but vase mode (which probably wouldn't work).

Other than using Cura, is there any way to fix this? I checked the guide and this wasn't covered.

== John ==

[jgwinner]

So basically it's a fail?

[parallyze]

So basically it's a fail?

Can you take a look at "Process -> Advanced -> Thin Wall Behavior -> External/Internal Thin Wall Type"?

Is it set to "Perimeters only" or "Allow single extrusion walls"? Does it make a difference changing that?

[jgwinner]

I've tried that setting both ways, and it didn't seem to make a big difference.

Sorry I missed the notification I had a message. The file in question is here: https://www.instructables.com/id/Body-C ... one-Mount/ although Shaun revised it to have a thicker edge. It wouldn't be hard to build a test case of an extruded triangle.

[parallyze]

I've tried that setting both ways, and it didn't seem to make a big difference.

Sorry I missed the notification I had a message. The file in question is here: https://www.instructables.com/id/Body-C ... one-Mount/ although Shaun revised it to have a thicker edge. It wouldn't be hard to build a test case of an extruded triangle.

None of the original image links is working any longer. Maybe you can add a factory file (File -> Save factory file as...) showing the problem? Others
can check settings very easily this way.

If I remember correctly there was a part which seemed to be "stuck on" instead of a solid perimeter all around. But I can't get
the problem reproduced using one of the STLs (followed the link from you to Instructables -> Thingiverse -> Thing Files, v0.83) and
can't see any problems using my settings:

Edit:
Problems start to appear when External Thin Wall Type is set to "Allow single extrusion walls" _and_ setting extrusion width
to manual >= 0.5mm. At auto/0.48 on a 0.4 nozzle this does not happen. So it'd be great to have the original factory file you
were having trouble with. The problem seems to occur with v0.73 and v0.83, didn't test the BLM one...

[jgwinner]

I had "Allow single extrusion walls" and "Allow single extrusion fill" as well as "Allowed perimeter overlap" at 12%

Minimum extrusion length was 1mm, minimum printing width was 50%, max 200%, and endpoint extension distance was .2mm. (I think some of those were defaults, but honestly can't remember).

Ok, I uploaded a factory file and the original STL here.

I was usually using a large nozzle, but even a .4mm did it. Looks like I was on Auto - with PetG I often go manual but set lower than Auto.

== John ==

[dkightley]

Having looked at the sequence of printing in the simulation for this part, I do see an issue that needs to be addressed by S3D's developers...

It looks as if the addition of the single extrusion processing has resulted in unexpected consequences where any thin wall sections are processed totally separately to normal perimeters. This is inadvertently creating the "aileron" effect described in this thread....and very clearly illustrated in the part in the attached factory file.

The single wall processing does need looking at again so it is processed as part of the existing perimeter processing....not separately to it.

I wouldn't classify this as a "bug" in the code....as the software is doing exactly what it should be doing, but I would classify this as a "deficiency in design" that needs resolution as soon as possible, as the deficiency is showing the slicer as "failing" to do its job - creating a good slice!

Like other changes that have been made, proper integration testing would have identified this as an issue!!

[S3D-Jake]

This may help: https://www.simplify3d.com/support/arti ... -features/

What you might want to look at for reducing any hinge type connections between thin wall features and normal perimeters is the Endpoint Extension Distance which is explained near the bottom of that article.