having trouble unioning solids. sketchup says they’re solid. if anyone can help i’d greatly appreciate it. perplexed.skp (273.4 KB)
What are you perplexed about specifically?
Yes they are all solids.
Yes they will union into one group.
No that group isn’t a solid.
But if you look inside you’ll find some stray edges around the holes whare the ‘fins’ join, remove those and it will be a solid.
I suspect it is due to the small size of your model, scaling up by 10 or 100 would probably union them without leaving edges.
Given your expressed distaste, @Box, of 
s, here’s a 
for cracking the case.
Scale the model up like Box says and the Solid Tools will work as expected.
Like so…
Un_perplexed.skp (204.4 KB)
@Box @geo thanks fellas. i’m confused when sketchup tells me two things are solid. i think it’s logical to think thaat adding those two things, would also produce a solid. i’m new to the tool so i’ve not yet mastered the nuance of the s/w.
The nuance is operations involving tiny geometry often force SketchUp to create new microscopic geometry far smaller than the application was ever intended to handle.
The workaround is to scale the model up and perform the necessary operations.
Then scale it back to original size when finished.
@geo thank you. what exactly should the internal geometry look like? should there be no intersections? also, is there a best practice for “trimming back” objects in planes where curved geometries make for difficult planar references?
A Solid in SketchUp is a single Group or Component whose geometry meets certain conditions.
When those conditions are met, Entity Info indicates the model is a Solid Group or Solid Component.
Also notice Entity Info indicates the Volume of a selected Solid.
• The geometry must form a single* airtight vessel.
Like a perfect soap bubble … •No gaps •No holes •No leaks
• No extraneous Faces** inside or outside the vessel.
All Faces must serve to enclose the singular volume of the vessel.
• No stray Edges.
All Edges must serve to support a Face that in turn serves to enclose the airtight vessel.
Thus, each Edge supports two Faces … no more, no less.
• No nested Groups or Components.
*A Solid Group or Solid Component may contain one or more separate airtight vessels.
**Best that all Faces are oriented Front Side (white) facing out.
Understanding Solid Objects in SketchUp — Aidan Chopra
• Programming & Web Design Articles - dummies
• http://www.aidanchopra.com/web-content/chapter-6/understanding-solids
Solid Inspection/Repair Tools
TIG: SolidSolver
ThomThom: Solid Inspector²
http://extensions.sketchup.com/en/content/solid-inspector²
I don’t quite understand the term difficult planar references.
Could you phrase the question a different way?