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dkightley
Posts: 2405
Joined: Tue Mar 10, 2015 4:09 pm

[ADDED] Slicer behavior for thin walled sections

I know this may be a duplication of other threads, but......

There have been many threads on the subject of how S3D behaves when dealing with thin walled sections....and I think its about time the designers took some time sooner rather than later to address the issues that have been discussed on the forum relating to thin walls. Here's a selection of recent threads:

viewtopic.php?f=9&t=3467

viewtopic.php?f=9&t=3458

viewtopic.php?f=9&t=3369

viewtopic.php?f=9&t=3360

viewtopic.php?f=8&t=3343

viewtopic.php?f=9&t=714

viewtopic.php?f=8&t=3316

viewtopic.php?f=9&t=3276

viewtopic.php?f=23&t=3171

viewtopic.php?f=8&t=3179

There are two issues.

Firstly, the behavior that if a single filament will not fit, then its not generated. This results in complaints about the slicer not working correctly....the arguement against this being that the printer should only work within what it physically can do and by not printing, it's highlighting an error in the design. A simple solution would be to have a check box to allow working one way or the other.

The second issue relates mainly to the quality of top & bottom surfaces where the width of the wall section is not a multiple of 2 times the extruded filament width...resulting in gaps and holes on the surface. The "Allow gap fill where necessary" option should get rid of the gaps....but it doesn't seem to do so reliably....and it certainly doesn't show up as having much of an effect on the print preview. A more effective gap filling control is required...preferrably one that does not need adjustment of several other options as well.

Edit 26th Jan 16 - another thread: viewtopic.php?f=23&t=1838
Last edited by dkightley on Tue Jan 26, 2016 10:51 am, edited 1 time in total.
Doug Kightley
Volunteer at the National Tramway Museum http://www.tramway.co.uk
Railway modeller and webmaster at http://www.talkingtgauge.net
rolfmeijer
Posts: 13
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Re: Slicer behavior for thin walled sections

+

I print original CAD drawings and scaled down, the wall thickness gives lot's of problems. There should be an option to print these thin walls with a minimum of x shells or the same size as the extruder.
wfcook
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Joined: Mon Jul 13, 2015 2:32 pm

Re: Slicer behavior for thin walled sections

Agreed, this is a major shortcoming of S3D.
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AK_Eric
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Re: Slicer behavior for thin walled sections

+1 : Now that I'm using a 1mm volcano nozzle, designs that should print are missing their walls. A frustrating shortcoming of the software.
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DollArtbyJulie
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Re: Slicer behavior for thin walled sections

I definitely agree that this is an issue on both counts
I have had to spend a whole weekend reworking a lot of my parts because they ended in a fine line, and the software didn't recognize it as thick enough so it would print it. There should definitely be a tick box where you can choose to preserve the outside wall at the minimum extruded thickness
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dkightley
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Re: Slicer behavior for thin walled sections

Here's another problem caused by this issue:

viewtopic.php?f=9&t=17
Doug Kightley
Volunteer at the National Tramway Museum http://www.tramway.co.uk
Railway modeller and webmaster at http://www.talkingtgauge.net
Fred B
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Re: Slicer behavior for thin walled sections

Cross sections below the extruder width don't currently print. This shouldn't be a surprise because we want accurate prints.

The other slicers that "force" thin walls to print will sacrifice accuracy. Why would we want to print inaccurate parts? It's more accurate to design features to print properly in the first place.

If they did add a feature it could be called "inaccurate thin wall mode"
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dkightley
Posts: 2405
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Re: Slicer behavior for thin walled sections

I'm with you on this, Fred. I wouldn't want something to print inaccurately!

But there are too many users who .....to put it politely......do not care if a print has inaccurate wall thicknesses...they just want it to print.

There are too many who say "It prints okay with XYZ slicer....which is free. Why doesn't it print with Simplify3D which costs mega bucks???" for the whole issue to be ignored.

For the sake of the reputation of S3D, this needs addressing......and sooner rather than later!
Doug Kightley
Volunteer at the National Tramway Museum http://www.tramway.co.uk
Railway modeller and webmaster at http://www.talkingtgauge.net
CompoundCarl
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Re: Slicer behavior for thin walled sections

I'm with Fred B on this. In fact, this is probably why the parts I print in S3D are more accurate than other programs. They are honoring the actual dimensions of the part and don't take random shortcuts or print outside the part outlines.

If they add an option called "print inaccurate thin walls", then we will just start to see lots of questions from people who are confused why their 0.2mm thick wall didn't print at the correct thickness using their 0.4mm nozzle. The fact that everyone is so surprised by this just shows that there is still some education needed on the limitations of FFF printing.
dsegel
Posts: 159
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Re: Slicer behavior for thin walled sections

How about "Use extrusion width as minimum wall size"? I could see this being difficult to code properly from an accuracy standpoint, though. You'd have to know whether to err on the inside or outside of the part/wall. Maybe that can be an option - "Use external dimensions as guide" vs "Use internal dimensions as guide".

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