Need clarification on S3D gap-fill settings

[HarmonicaSail]

Factory file is attached. My settings are:

• Extrusion width 0.5 (and it is confirmed to be extruding 0.5047 mm).
• Allow gap fill when necessary
• Allowed perimeter overlap 50%
• Perimeters 2

I wanted to know when S3D began generating gap-fill, so I made an STL in OpenSCAD that generated ribs of varying thickness. Their thickness increased from 0.0 mm thick to 2.0 mm thick in 0.05 mm increments. I imported and sliced it, but the gap-fill only began to appear at 1.45 mm thickness and the perimeter infill only appeared at 1.55 mm thickness.



Since my overlap is 50%, I expected the perimeter infill to come in much earlier, starting at 1.25 mm thickness as the diagram below shows:



The above diagram is my understanding of what S3D should be doing. We've got three cubes signifying the perimeters. The middle perimeter (brown) overlaps the outer perimeters (blue) by 25% on both of its sides, leaving 50% of the middle perimeter not-overlapped.

Instead, this is what we get. A gap between the layers, which is the opposite of an overlap!



Could we please get either a fix or a better explanation of what gap-fill is actually doing? Because it's clear that "Allowed perimeter overlap" should probably be renamed to something like, "Preference for interior perimeter".

[CompoundCarl]

You have some very odd gap fill settings, which are affecting when the gap fill is used. Here's what I would do personally

• Adjust the allowed perimeter overlap to something a bit more reasonable, in the range of 10-30%. If you use 50%, you're kind of defeating the purpose of gap fill and you're going to get perimeters that are too close together.
• Next, keep in mind that the gap fill will use some of your standard infill settings (since it is essentially infill itself). If you want gap fill to be able to fit into smaller spaces (such as some of your smaller slats), then you need to make sure the infill is allowed to overlap with the perimeters more. So go to the Infill tab and increase the infill "outline overlap" to something a bit larger (I used 25%).

Changing those two settings makes a big difference. I attached a screenshot of what it looks like when slicing now.

Hopefully the explanation helped!

[HarmonicaSail]

Thanks for that! It definitely helps to have gap-fill coming in at 1.30 mm instead of 1.45 mm.

[maker2]

I too am confused by "perimeter overlap".

Playing with the setting, I have the impression that the greater the "perimeter overlap" the LESS LIKELY you will find gap fill in a narrow space?

That is exactly the opposite of what I would "expect".

If you are increasing the amount of "overlap" allowed with the perimeter wall, then surely you are creating MORE space to fit in gap fill, so one might expect it to be MORE likely to find gap fill in a given space.

Can anyone explain?

[HarmonicaSail]

That's exactly why I made this thread, and why I suggested that the feature should be renamed to "Preference for interior perimeter" because that seems to be closer to what it's actually doing. It was great to get a solution to the problem, but it would be better to truly understand it.

[maker2]

Thanks.

I'm starting to think that what it means is NOT the allowed overlap between Gapfill and Perimeter

BUT between Perimeter and Perimeter.

In certain situations a second or third perimeter is not "allowed" because of space constraints. So perhaps Gapfill will be printed. However if Perimeters are allowed to overlap by a large enough percentage, then another perimeter can be squeezed in.

Perhaps.

It certainly is confusing!

And if perimeters do overlap by more than a little bit, where does all the plastic go?

[BlankMan]

You have some very odd gap fill settings, which are affecting when the gap fill is used. Here's what I would do personally

• Adjust the allowed perimeter overlap to something a bit more reasonable, in the range of 10-30%. If you use 50%, you're kind of defeating the purpose of gap fill and you're going to get perimeters that are too close together.
• Next, keep in mind that the gap fill will use some of your standard infill settings (since it is essentially infill itself). If you want gap fill to be able to fit into smaller spaces (such as some of your smaller slats), then you need to make sure the infill is allowed to overlap with the perimeters more. So go to the Infill tab and increase the infill "outline overlap" to something a bit larger (I used 25%).

Changing those two settings makes a big difference. I attached a screenshot of what it looks like when slicing now.

Hopefully the explanation helped!
GapFill.png

Thank you this post. I was having trouble with the first layer (and actually subsequent layers) of my model on a raft, the perimeters were fine but fill between the perimeters was kind of sparse. Knowing now that infill parameters affected this allowed me to improve that first and subsequent outer layers.

I thought that the infill parameters were only for the internal orange infill and not the edge i.e. outer surfaces a.k.a. top and bottom.

[CitySlicker]

Thanks for the advice regarding these settings.

I found it useful to modify the settings by trial and error using a series of spaced ribs as per HarmonicaSail

I recreated a test model making it easier to identify dimensions, see attached and below.