Don't know what you mean by "total chamfer". The only features you can create in assemblies are hole, extrude, and revolve. Additionally, the extrude and revolves can only be used to do material removals. You can't make chamfers or rounds. Those need to be done in the part models.
Making assembly cuts is not something most people do unless they absolutely have to because in the past it has tended to behave strangely, especially if you add components to your assembly after adding the cut. It's considered to be bad practice for most situations. Part reusability is one very good reason, for example.
