Perhaps one of the most important things to keep in mind when designing a DIY machine is that you cannot just copy a commercially produced design. Those machines are designed to have their components accurately made by another machine as Dean points out. Without that luxury most of us are hand drilling, filing and shimming a bespoke machine which must be designed as such.

On this note I can highly recommend the book I'm reading at the moment... 'Exactly' by Simon Winchester. 'How precision engineers created the modern world'. Fascinating stuff for the likes of anyone likely to be reading this post. Have it delivered by wireless to your Kindle (the best invention since the printing press).