Noob question: trouble keeping drawings solid for boolean transformations



As a beginner, I’m having trouble keeping sketches solid so that they can be grouped and have boolean transformations performed upon them.

Rather than try to explain it out, I took a screen recording of the issue. The shape I start with was traced over an in imported image of a technical drawing. It is a complete, closed loop as far as I can tell (it has faces, I thought that was a requirement of faces)

The actual boolean transformation I need to perform is not what is shown. But, in trying to figure out my problem I just wanted to get any shape to perform a boolean.


Very likely you are running into the small faces issue. Try working at a larger scale or use the Dave Method which Box created a tutorial for in the Tutorias forum.


In addition to Dave, from what I see…
Where the circular shape meets the longer part I think there is a face inside there. An internal face. Sketchup doesn’t know which way is inside/outside because of that and doesn’t recognise it as a SketchUp Solid.

When you make the group select it and in Entity info it will report as “Group” or “Solid Group” if it is actually solid.
A good troubleshooter I find is an extension called “Solid Inspector 2” which is available from the SketchUp extension warehouse from within SketchUp. Once installed it basically scans a group or component and will report any errors. In many cases it will be able to fix the errors automatically for you, or you will have to fix the error manually sometimes. It’s a very easy way to help get solids.


@DaveR Thanks for the suggestion. I did google a bit before posting and saw that scale was a potential issue. So, I already had tried scaling up 10x from mm to cm. scaling up to meters caused zoom and rotate to be obnoxious. So, I crossed my fingers cm would be large enough. That said, I skipped to Ian’s suggestion as it might be easier.

@IanT gets the cookie. 7 internal faces, 2 external faces, 11 reversed faces. Fix, Fix, Fix, Done. Everything working great. Thanks for the tip.

Great community here. Thanks to everyone. Cheers.


There’s also an extension available through the SketchUCation plug-in store called Solid Solver that will boolean any groups together and make a perfect solid when finished.

Navigate yourself over to:

And then, once you install the extension store - search for Solid Solver.


I would be inclined the ditch those groups for components which are my preference. I only use groups if I know I’m going to delete them from the the model. It saves them from being hung up in the in model components which need purging to get rid of.
You should look up the Dave Method which leverages one of the many benefits of components. It’s only a matter of time until you’ll run into the small face issue. Using that method you draw everything at real size but only scale a copy of the “problem part” leaving all the original parts in situ.

When you scale up to work on larger copies, hit “zoom extents” to bring everything into the model window. Also try to keep your work at the origin area of the model, the further away you get the more difficult zooming and orbiting becomes.

Oh also, don’t get lazy with face orientation because of Solid Inspector, you should fix reversed faces as soon as you see them. After a while Solid Inspector will kind of “teach” you what’s solid and what isn’t. So as you model you’ll know to fix things and often you won’t need it anyway.


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