I'm editing an assembly, and I created an internal part inside of it. I want the part's planes to be the same as the assembly planes. I tried to set a mate between them, but it tells me those planes are already fully defined-- despite the fact that the part is not fixed and has no mates.
How can I change the part's planes to be like the assembly's?
Parts created within an assembly, and not existing as a seperate part file (virtual part), are by default fixed with their three primary planes aligned with those of the assembly. If for some reason that isn't the case, or if you want to align the part differently, you should be able to right-click on it and choose "Float" from the drop-down. Then you can mate it just like any other part.