Howdy Ford,
Well, my point is representing a design of a machine and representing a design of a timberframe are one in the same. The hard part is making it work. Any type of designing program or even pencil will work if done with discipline. I have seen architectural drawings of one house that are at least a hundred pages all done on a drafting board with pencil and ink. But to jump off my soapbox and answer your question. Sketchup is a good start after pencil and paper. Cad is better but definetly not budget friendly for those concerned with anti-piracy laws.
p.s. search the software topic area. If you do not know how to use sketchup there are some great contributions in there for learning.
