Skinning issue for STL model


I’m new to SU so please bear with me.
Firstly, I’m not new to modelling although it has been a number of years since my Lightwave days, so I’d like to say that SU is an awesome tool.

So, after I wrote my post I was informed I could only show 1 image, so I will add links instead (just add the “h” at the beginning of the link).
Now to my issue. I created a cube with intersecting edges so that each side of the cube could slot into the other, with the corners locking the sides in, thusly:

This is the exploded views:

There are essentially only 2 components: 1 for the 4 sides, and 1 for the top and bottom. Each of the 2 components is hollow with a 1mm 2-walled “skin” on the front and back faces, like so:


The problem that I am having is that when I export the object as an STL file and load it into Slic3r, I get a skin that covers areas where there should be none, as can be seen here:


Now I’m not sure where this issue is arising from, and as I’m new to both SU and 3D printing, was hoping that someone here could point me in the right direction to start troubleshooting the issue.

Thanks for any and all help. I have attached the SU file for anyone who wants to see the actual model itself, you can get it here:

Thank you,
Paul Allsopp aka webtop


One thing I notice in your model is that the components aren’t SketchUp solid shapes. They all have internal faces. Clean up the components (get rid of these faces inside) and see if the ‘Entity Info’ dialog box reports them as being solid components with a volume. Each edge should only have no more and no less than two faces connected to it, resulting in a watertight empty shape. Then export.


As has been said…

The model’s component parts are NOT ‘solids’.
The Entity Info top-bar will show them a ‘Solid’ IF they are.
There are issues like internal faces,… also Component#4 has reversed faces.
Hiding faces doesn’t mean they disappear: you must erase then.
A manifold solid can only contain faces and edges.
Every edge must have only TWO faces, no fewer and no more !
Internal partitions have three or more faces for some of their edges…

Once all the bits are made as solids, you may also need to export them separately as STL files, so it can be printed as separate parts.
But IF you want this thing printing as a single object then that’s something else… model the thing as a solid, merging the parts and removing internal partitions etc.

A useful tool for testing a group/component’s solidity so you can manually fix it, is thmthom’s Sold-Inspector:
Note it also needs his Lib installing:

There are several plugins to help make things solid, but understanding the issues, and fixing them by hand so you don’t repeat them is a VERY useful experience…


Thank you very much for the replies. I had started with a different design, and changed it twice before deciding I liked this one, so I guess I lost my way in there somewhere and didn’t see it.

I will start over with the end in mind, now knowing the SU toolbox a little better.

Thanks again.