What will part 12 in the drawing say about the designs? (in the patent US20040213428)
Can I use same design on the part but with an other angle?
One of the purposes of the patent system is for others to learn from what an inventor has laid out. However, what aspects of the teachings of a patent document are and are not fair game can be difficult to determine. In this case the document you referenced is an application for a patent, not a patent. As such it would not stop anyone from doing anything. The first step is to look it up in some patent database to see if it resulted in a patent. Checking USPTO PAIR I see that it produced an issued patent 7,072,483. The claims of that patent define a set of things you can't do. That is the easy part. Has the rest of what the application taught been dedicated to the public? Maybe. If there are continuation applications on file or other counterparts in existence those may have additional claims beyond this patent. Also, the fact that this patent may not claim something doesn't mean it is necessarily fair game. Some other patent by the same or different inventors may cover it. Being outside the scope of one patent's claims does not mean something is outside the scope of all patents' claims.