I am experiencing with sketchup, but I have now a situation I can not figure out. Solid inspector says all ok but when I want to use solid tools on the part sketchup says not a solid.
Model is no more a solid when I pushpull the front lip. Do you know what I am missing?
Somehow you have created a very strange curve, it is irregular without creating the correct faces, I can repair it but you’d be better off starting from scratch with a clean curve.
You can see in the gif how the edge isn’t continuous and there are less faces than the fix one.
I’ll add the model with the fixed version for you to look at, but I’d suggest you make a new one. backplateBox.skp (2.4 MB)
Working off of the comment made by Box about starting over with clean curves I redrew your model. Before you start, go to Window>Model Info>Units. Untick Length Snapping and set the display precision higher so you can see small discrepancies in dimensions.
So from left to right:
I started with the Pie tool to draw the outside arc. Then extruded that to the thickness of the flat part before outlining the shape.
Push/Pull to remove the inner part.
Push/Pull again to raise the wall. Then make a group or component. Solid from the start. No cleanup required.
One thing that I find useful for modeling this kind of stuff is to think about how it would get printed. Don’t add features until you get to them. Many new users tend to think in 2D for too long. They end up drawing all the feature outlines before they start extruding.
In this case I modeled only half, then copied and flipped the copy to make the upper half. Bevels were added with Follow Me afterward. And first printed drafts.