Is there any technical info available that's in print form that is available online, or is most of it copy written?

I'm always wondering about the "correct" method or material when I'm cobbling something together. I don't have any formal education in engineering or physics, so I always just "wing it" the best that I can with the info, ideas, and materials that I have on hand, or know where to get. I feel like a lot of the projects I see online is of guys like me that are "winging it", which is great..., but I'd really like to understand the proper way to design things too. Just because a tool or machine "works" doesn't mean that it couldn't work better or be safer with just a "little bit more" knowledge.

There is a lot of technology and materials that I don't know about, don't understand, or don't know where to obtain. Some of it is new technology, but a lot of it is old technology that has become obsolete. Lindsay Publications used to sell a lot of old & reprinted books & manuals. Are there any sources like that which are available as free or paid e-books?

This site is great for photos and videos, but most of what I have found is DIY designed, and I'd like to get more of an educated overview about the technical aspects of things. It would be great if we had a "library" here, of basic materials, techniques, components and how to choose the specs for our projects. (Things like, types of motors, bearings, gears, pulleys, fasteners, etc.) Old tech school text books would be great.

Does info like this available somewhere here, or elsewhere on line?