Things have moved on in the last week or so.. I did my back in picking some paper of the floor by my desk :( so no hard work on the machines and a couple of days off work at home.

Got a bit carried away on fleabay (you know how it is! :) ) and now have enough material for a 300mm X axis and a 200mm Y axis (rails, linear bearings, leadscrew) plus 4 steppers, a 500VA transformer and a 22000uF smoothing capacitor. Stepper driver chip samples are on the way as are power transistors and a few other parts...

Haven't quite worked out what I am going to build exactly but something that will mill PCBs and light aluminium work. All the calcs I have done suggest I could take a .15mm cut with a 10mm endmill in 6061-T6 ali with the stuff I have.

This will need a 50W spindle motor at 3000rpm. I'd want this to be as lightweight as possible and looking at motors that could do the job I was dismayed by their weight (typically 2 - 3kg). Then I was reading up about coolant and how mist cooling is the 'next big thing' and I was musing on how I could use my air compressor to provide the pressurisation using a modified airbrush head when an idea dawned.... why not use the air pressure to drive the milling spindle?

So, has anyone done this and if not, why not?