I can't work out how to join these two bodies

[collinsbenji13]

Hello. I'm trying to combine two solid bodies but I keep getting the error:

"Error: There was a problem combining geometry together.
If attempting a Join/Cut/Intersect, try to ensure that the bodies have a clear overlap (problems can occur where faces and edges are nearly coincident).
Failed to Boolean bodies together"

There is definitely overlap between the two, I can't see any weird edges or faces. They are fairly simple shapes. I have attached the f3d files. What steps should I try next? Please note that this is a part for a toy.

Thank you in advance.

[TheCADWhisperer]

@collinsbenji13 

Why is your first sketch (and all other sketches) not fully defined?

Why use stl faceted geometry rather than clean Revolve?

Step1. I would move the Canvas such that the Origin is in a logical location (and is the Canvas the right size?).

As I start to remodel this from scratch - as I add missing dimensions they do not make logical sense?

If I do a Compute All (CTRL b on Windows or CMD b on Mac) I get a whole list of unresolved issues?

I am left with a conundrum of how to proceed without calipers and the actual part?

I can try to reverse-engineer the imported meshes and try to decipher true Design Intent...

I can recognize some Face Groups...

And generate a Prismatic Model...

Bit-by-bit I build the geometry...