Jeff,

That looks really impressive. Some questions & thoughts...

The Y-axis looks like ally box section welded to some end plates, is that the case and if so what did you weld them with? and how did you get them square? The y-Axis supports, are they the thick PVC you mentioned earlier? were they milled to the T-shape for the mounting on the X-axis pillow blocks or is that 2 pieces joined?

Even tho my first MDF build isn't yet complete I'm already planning a ally and/or steel build, poss a 4-axis job that can act as a lathe too...

Instead of energy chain, which is expensive and bulky IMHO, have you considered using a spring pole (think of a bendy fishing rod) and bringing the cables down from above?