Shape fails 3D printing manufacturability analysis

I am hoping to make my own stackable coasters, by creating a sketchup model, exporting it to a STL file and getting it sent off to be 3D printed. When uploaded to the 3D printing website, it claims the file is ‘Broken’.
I am a newbie to sketchup and 3D modelling so any help would be much appreciated! Thanks :slight_smile:

coaster 3.skp (1.3 MB)

A section cut will make clear what the problem is. You have internal faces and a gap in the surface.

There’s also exposed reversed faces.

The easiest way to model this thing would be to draw a cross section and use Follow Me around a circle.

Compare yours on the right to mine on the left.

In order to be consider a solid every edge must be shared by exactly 2 faces, no more and no less. So no stray lines, no holes in surfaces and no internal faces. Face orientation is important. The printing media goes on the back face (blue) side of surfaces.


Thank you so much will give this a go now! :slight_smile:

Good luck. Note my edit to my previous post.

I was doing a gif but saw dave replying so I stopped.

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Would you be willing to share your sketchup file alteration? Looks drawn to perfection! Also does this mean that the blue side should be facing outwards for 3D printing?

Feel free to share!:slight_smile:

Here you go. I left yours in there.

No. The blue should be facing inwards. If after running Follow Me you have the blue faces outward, you need to select the surfaces, right click and choose Reverse Faces.
coaster 3.skp (1.7 MB)

By the way, when modeling round things like this, I think it’s a good idea to work so you are centered on the origin. That gives you a nice fixed center point to work off of.

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Here’s a quickie using the axis as Dave points out. I also only used 86 segments, actually a strange number I would normally have used 96, dividable by 12, rather than your rather odd 193. But you can increase it if you need to.
And if you are using 2017 the Weld Edges option I used won’t be natively available.
Anyway, it shows one method.

Thank you both so much! How would I make the circular elements smoother and increase the segments? Can you make a ‘perfect circle’ or at least close?

You can’t make a ‘perfect circle’ in SU. Circles and arcs are always drawn with short straight segments. But while it is still a circle, before you run FollowMe, you can edit the number of segments (in Entity Info) up to a maximum of 999.

Normally, it’s a good idea to make the number of segments in a circle or arc a multiple 12, or at least of 8, 6 or 4, so you get clean intersections at a range of angles.

But 193 is a weird number to use. Why that number? Did you mean to use 192?

Hi John,
As a beginner with SU I was sort of ‘winging’ the drawing process. Thank you for the tip, may have to start the model again from the start!:frowning:

Using the process Dave and Box have shown you, it should only take a few minutes.

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If you take a good look at the gif @Box showed you, you can see him change the number of segments!!

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Thank you!

For 3D printing the lenght of one segment should ideally be 1 mm to make it seem smooth (unsegmented).
So for good practice, use a multiple of 12 that gives you a segment length of around 1mm…