Machine Shop Essentials is an excellent reference for the metal-working novice and professional alike. Geared towards small prototype R&D shops that mostly rely on manual machine tools, this book describes the basics and some of the more advanced concepts in the field.
Done in a question-and-answer format, the questions answer everything from basic to more advanced topics. This book covers many of the essentials needed for skillfully operating basic machine tools and also includes hand tool basics, measurement & layout, fastening methods, some steel metallurgy, safety and other shop know-how.
Additionally, many entries serve as a good reminder and overview covering those practices that we've learned, but may forget over time. So, this book is definitely an excellent addition to any metalworking library.