Fixing non manifold parts for 3D printing

revelever

Hi All-

I am printing this model of a telephone, see attached. Its going to have some functionality, the buttons with interact with a raspberry pi inside, and there will be a speaker in the handset. I've received it from the designer and parted it out into mostly printable pieces. There are two issues:

I would like to 'boolean' out some holes for the buttons. I think I know how to approach this, but I wanted to run it by you. What I would do is transfer the shape of the buttons to the face of the phone body, then use the offset tool to enlarge those shaped a tad, then push pull them through.

Also, some of the pieces are non manifold. Whats a good way to go about fixing this?

thank you,

-rev

sept_8~.skp.zip

TIG

Your shapes are not solid because they have several issues.
They are often not a continuous surface - e.g. the meeting surfaces of the two halves of the 'case' are not 'faced'.
There are also several 'unfaced' edges, or parts that do not 'intersect' with adjacent geometry.

Coloring faces [before you are done fixing] confuses the issue too.
View your model in Monochrome mode: if you see blue internal faces then either they are incorrectly oriented or there are faces missing and you are seeing 'inside' the form.

Make each discrete 'part' as a group.
That way it'll report as 'Solid' in the top-bar of Entity Info - IF/when it's fixed.
This will make the task of debugging the geometry clearer...

Use a combination of X-ray mode and temporary section-planes to see issues inside your forms.
Then you can overdraw hole-edges to generate needed faces, or select and erase unwanted edges/faces...

Thomthom has two plugins - Solid-Inspector which highlights issues for you to then fix manually and Solid-Inspector2 which attempts to fix them too.
I also have a similar tool 'SolidSolver'.
However, the power of your brain in fixing major issues will outstrip any coded algorithms, so I suggest you try to fix things manually and only resort to Plugins if problems are 'stubborn'...

Here are the basic rules for modeling 'manifold solids'...

Any solid Group or Component-Instances must contain ONLY geometry - edges and faces.
This means no nested groups or components [explode them if necessary], or other entities like Text or Dims.
Every Edge must support exactly two Faces.
That means there can be no faceless-edges; no edges forming a flap, shelf or a perimeter of a 'hole' in the surface of the form; no internal partition faces, which will then have three or more faces; and no otherwise solid forms sharing a common-edge - e.g. two cubes touching at an edge, where that edge will have four faces !
Also orient all faces consistently, will the blue 'back' material internal in every case.
Also remember that SketchUp's tolerance is 1/1000" or faces of <~1mm² area , so if any modeling might result in edges with start/end points at or below that they are deemed coincident and the edge is not created, then any faces reliant on that edge are also omitted.
If you are making small real size objects with tiny curving facets etc, then the way to avoid this issue is to scale by x100 or more and the edges/faces will then be created - later you can scale back down to the required size and the tiny geometry will still exist - remember "tiny geometry can exist, but it cannot be created"...
Another thing to remember is that a 'Solid' in SketchUp can also have a subtle issue preventing successful 3d-printing - if a form is convoluted and has geometry penetrating itself then it's not printable, BUT if can report as 'Solid'. To check for this, once the form is reporting as Solid, Edit the container and use Edit > Select All, then use the Context-menu > Intersect > With Context... If you exit the Edit and it still reports as a 'Solid' all is well, but if it is now a non-solid the intersection has created internal partition faces which need deleting to restore solidity [so just do a Section-Cut and delete those etc...]

Tip: Always make [or put] all edge/face geometry on Layer0 - only assign other Layers to control the visibility of each 'container' of that geometry [i.e. a Group or Component [useful when repeated parts are appropriate]].

olishea

Great advice TIG bookmarked