[ASmith1675]

CAD is merely a tool. When used in effective combination with prototyping and effective game analysis it can help to raise your capabilities.

Designing a robot completely within a CAD program will allow you to see issues and interferences in 3d space that you may not have accounted for with a design in your head, or even on paper sometimes. The more detailed the CAD model, the less likely you'll run in to these type of issues while building.

To make full use of these advantages requires a slight change in thinking (in my opinion). While simply building things in a computer may not feel like much is getting done, by properly planning out where everything is going to fit, it reduces the time to put everything together. This might mean you don't have ANY parts for your robot for week three (or later sometimes).

The other thing that needs to be taken into account is the manufacturing capabilities of your team. If you don't have access to a mill (manual or CNC) you may have to account for the lower accuracy with which a part can be manufactured. If you have a sheet metal sponsor, you may be able to have parts cut and bent to very high precision. These issues are the ones that are often most difficult to account for. (Can't tell you how many times I've thought of a design that would be difficult/impossible to manufacture given the facilities and resources of the team that I am working with).

CAD is just a part of the equation, though arguably a big one. Being able to effectively analyze the game (to pick the right mechanisms to build), and prototype effectively (to verify your "theory" designs work in the real world), also play a critical role. Can you build an effective robot without CAD? Definitely. I do believe that becoming more proficient with CAD will tend to increase the consistency of robot builds year after year (meaning fewer of the "our robot didn't do what we wanted" years).

The other posters in this thread have provided some excellent resources to get started. Just digging in and messing around with the programs is a great way to learn.