Difference between skin, shell, and walls?

[lordnimon 1]

What is the difference among these three terms?  Under "Infill" settings, I can set the "infill overlap" and "skin overlap" percentages.  Under "Shell" settings, it talks about Wall overlaps.  Skin overlap defaults to 5% and 0.02mm -- why both settings?  Don't they conflict?  And why does infill overlap default to 0?  Shouldn't it also be 5%

Edited March 25, 2018 by lordnimon

[boogieman 1]

The skin are the topmost layer, so the "skin overlap" is the overlap between the wall of these layers and their filling.

The "infill overlap" is the overlap between the wall and the infill, i.e. inside the object/ below the skin.

In the shell section you talk about, there is the setting for wall overlap compensation. This is for reducing the extrusion in areas where the print head has to go over twice while printing the wall. (see ttps://ultimaker.com/en/resources/20415-shell)

[eldrick 65]

It would be nice for Cura settings to use consistent terminology...

 

[Fabiuz 2]

Speaking about Bridges, is "skin" the first (the lowest) layer of the bridge?

[rburema 26]

The only part that is really inconsistent is the Line Type - Color Scheme legend (also the Skin Overlap settings should be in the Shell catagory I guess.)

 

Concerning the settings (not the Line Type as shown in Preview):

 - Shell is all outer parts / (near the) outside of the model.

 - Walls are the vertical (enough) parts of the shell, and thus part of the shell. (They're red and green in the preview.)

 - Skin is the horizontal parts of the shell, and also part of it. Not just the top, but also the bottom! Yes, this also means that the lowest layer of a bridge is skin.

 

This also (sort of) answers the questions (together with the hover-over explanations), Shell is the catagory, there the wall-overlap settings are for walls overlapping _each other_. In the Infill catagory, there is the infill overlap settings, which handles the overlap between the infill and the walls. Then there's (also in the Infill catagory, which it probably shouldn't) the skin overlap settings, which handle overlap between wall and skin (since the walls take precendence over skin, unless you set the nr. of walls to 0, there's going to be walls on each layer there's skin as well).

 

There is a default skin overlap to make the shell look a bit better, but that's normally not needed for the infill (though 'looking better' is not the only reason you could want overlap).

 

As an aside, in the 'Color Scheme' legend in the Line Type menu of the Preview screen:

 - It says 'Shell' here, but it's really just the outer wall that's red.

 - It says only top/bottom and infill is yellow (infill will be orange from 4.2 onwards b.t.w. ... or more orange I sould say since it already was a _slightly_ different shade of yellow. Also support interface will be darker blue than the rest of support.) but due to technical reasons, wall-filling (not to be confused with infill) is also yellow. Wall filling is used when a wall can not be made thicker, and there's still a gap to the next wall that should also be part of the wall and not infill.

 

P.S. What is 'outside' or 'close to outside' can be a bit counterintuitive sometimes though. There are cases where skin shows up in what can be argued is the middle of the model. Let's not get into that since it requires me to make drawings, and this is already taking quite long.

 

P.P.S.: Thanks for the question, it revealed two hopefully easy to fix issues. (Unless there are _reasons_ I'm unaware of, which tends to happen as well.)

[sharktank 2]

Ok this isn't going to be really fair because the question asked and answered here are more complicated than "what is a skin". But I have yet to see TeamUltimaker answer this question and since this was about skins and got convoluted just like their answers to "what is a skin", I thought I would bring it up here.

Why is it the public can express these concepts better than the people who create them?

See this link

https://www.reddit.com/r/3Dprinting/comments/afimpy/cura_what_is_top_surface_skin_layers_and_why_does/

This may be why the pop up help balloons aren't very good either. Setting: "Skin Edge Support Thickness".  Ballon: "Thickness of the infill that supports the skin edges"

Remember when the teacher said you couldn't use the word you were to give a definition for in the definition itself? Ya, that!

[burtoogle 516]

4 minutes ago, sharktank said:

Setting: "Skin Edge Support Thickness".  Ballon: "Thickness of the infill that supports the skin edges"

Remember when the teacher said you couldn't use the word you were to give a definition for in the definition itself? Ya, that!

 

One purpose of the blurb is to clarify what the setting label is hinting at. By necessity, the labels are often terse to the point of incomprehension so it's not at all a bad thing to provide a slightly longer version of the label in the blurb.