In the screenshot below, Im trying to make those two faces, but it tells me that...
"The default mate type (coincident) would over-define the assembly."
How does it over define it if there is only two mates in there, both coincident?
without being able to check the model/assembly files - the first 2 things to come to mind are;
1) are either componet "fixed"?
2) perhaps faces you expect to be perpinducualr are not.
I would add the file in here but I don't see option for attachment.
However, I checked in sketch mode on both parts and everything is 90 degrees.
edit: i added the files to original post
Rather than selecting two flat faces to mate, select the flat face of the base and select the vertex of one of the linear edges of the structural member. Mate these two entities coincident.
Neeraj, the face on the extrude that you are using to mate must not be prefectly parrallel to the wheel caster. Try mating a different surface on the extrude and it should work for you. I got it to work for me.
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