A few days ago we were discussing _Precision Machine Design_, which is an excellent book for people interested in machine tool and other machine design, but which costs $100. It was written by Alexander Slocum of MIT.
Slocum teaches (among other courses) a basic mechanical engineering design course called "Design and Manufacturing 1." To support the course he's written a stripped-down version of _PMD_ and made it available free, online. If you want to know about basic design engineering ideas, this is it. It looks like it's written for Freshmen or Sophomores -- simple language, excellent introduction of concepts, lots of first-semester calculus. But you don't need the calculus to understand it.
You can get it here:The book is under revision so the online PDF version is down. But you can get the last version in the form of a *.zip file that expands to a bunch of PDFs. Look in the left column under "Resources" for the *.zip, plus some other ones that look interesting but that I haven't checked.
-- Ed Huntress