Whenever you have a customer part, or some other model which you do not want to change when adding machining operations, you can use machining assemblies.
The following steps represent the fastest way to create an assembly from a part:
- Open the part file which you want to machine.
- From the File menu choose Make Assembly from Part.
This will create a new assembly file,
and preselect the already opened part document as the component to insert.
at the top of the property manager.
Alternatively, you can click in the model view window, but simply clicking OK lines up the origin of the part and the assembly.
Save the new assembly, giving it a name indicating that it has machining in it.