The design and modeling processes are inextricably interdependent! It is difficult and irresponsible to design processes, machines, or other products without modeling how they will look and perform. Parametric Solid Modeling (PSM) is a useful tool which will help you mathematically (geometrically) model your design(s.) It will also make your life easier and more productive as it will help:
The introduction of PSM does not mean the demise of sketching!!! Sketching is one of the most valuable skills a designer can have to quickly convey ideas and layout a design. As a matter of fact, it is often a GOOD idea to sketch out your designs before you proceed with PSM so that you can start to recognize the major shapes that make up your part. This is important as robust solid models are made of the fewest and least likely to change features one need.
Like the design process, PSM is best done when following a process. The general steps are listed below.
Basic Functions in Parametric Solid Modeling
Before discussing PSM in more detail, the reader should be familiar with the basic operations which can be used to make a solid model of a part/product. Note that when applicable, the illustrations below start out with a 2D sketch, then are transformed into 3-D geometry. The basic process may differ somewhat, depending on the CAD program you use.
Good Design Intent is the Key to Robust Solid Models
When we say "robust", we mean robust with respect to the design process. The goal of the PSM process is to make a model which can later be changed without messing up the original design intent. For example, suppose you have to make the piece shown below. The design intent is to have the hole centered in the middle of the cube. The correct and incorrect ways to solid model the part are shown in the table below.
We will cover more topics and go into detail on design intent in the lectures.