Quote Originally Posted by Neale View Post
My approach to this problem was to use 20mm rails, and 20mm Ecocast plate. This gave enough depth of material to be able to pocket the plates for clearance around the nut holder. The important point here is that the pocketing is for clearance and is not super-critical in terms of dimension.
This is the easist and best way to build a Z axis. Packing rails off or bearings off is a fiddly bodge. 15mm rails while more than strong enough are fiddly things and make it awkward.
You could go with 25mm rails and get away with no machining but then it gets tight with space and really requires a wider Z axis, plus there's more mass to deal with.

Hand machining isn't difficult provided your comfortable using a large router. I did several of the parts for my first machine this way and was the one who talked Joe into giving it a go, however Joe cut far more parts than I did using this method and made a very nice job of it so I'd advise anyone thinking to do this to go check out how he did it.!