Intersecting 2 curved surfaces

I see that others have had similar problems with the Intersect Faces tool and I have searched (and searched and searched) and tried (and tried and tried!) to find a solution to my particular problem. I officially give up!

Forum Q.skp (394.6 KB)

Am trying to get a spherical indentation into the bottom piece. I have tried various way to create a circle and used the intersect faces tool to get the indent I need but every time I try the remaining ‘line’ in the bottom piece is broken and therefore useless.

I suspect it may have something to do with the geometry of the circle (segment count for example) does not match the geometry of the curved surface and it is then missing parts when intersecting faces.

Please someone tell me what I am doing wrong.


Scale up x100. Intersect the faces. Scale back down x.01.

SketchUp does not do well with small geometry.

Like this?

I converted the group to a component, made a copy of all and scaled the copy up. Then I did the intersection. This has become known as the Dave Method. No need to scale back down after eding at the larger size.

Also make sure you correct the face orientation so you have white front faces out.

Try this:
Make the shape that gets the indentation into a component. Create a short cylinder whose bottom face is rounded–the shape you want for the spherical indentation in the other shape. Move the cylinder into position so that it’s embedded in the other shape. Cut the cylinder, open the shape component for editing, and go to Edit>Paste in place to put the cylinder within the component.
Copy the component and scale up the copy 100x. Open the big copy, select everything, right-click and choose Intersect faces>With selection. Erase the waste until you see the ihdentation.
Close the big copy, delete it, and use Zoom Extents to bring the original component into view.

Scale up. It worked perfectly. Cheers all (and hats off to ‘Dave’).

Thank you very much!

—insert sound of medieval trumpet fanfare—

1 Like

Very good. Don’t forget to correct the face orientation.

What’s down there by the origin?

Will change the face orientation now. Thanks for reminding me.

Origin is the mess of circles and spheres and broken lines (the general detritus of my various failed attempts). Will scale back down and clear them out.

Going to cut it now - will share results.

If you used the Dave method there’s no need to scale back down. :wink: