Gents, thanks for all the great info! I'll do the layout this weekend and figure out what size I actually need but I'm getting the feeling I'm in for a nasty surprise. I don't plan to put the PC inside the box and the PC power supply is only to power my bob, switches and relays. I'll read up on the Pilz thing to figure out what its for.

1) What's the reason for not putting the vfd in the box? Heat or electrical noise? Mine has lots of ventilation holes in it and I was thinking the best way to keep aluminium chips out of it was to put it inside my box but if that's a bad plan I need to rethink my strategy?

2) I got 4 x 80mm PC fans for the cooling. The uncool neon green ones with the LEDS but they were cheap:-) Was thinking 3 sucking air in thru a filter at the box bottom and one out at the top left. Would that provide enough airflow considering the climate is quite hot here and 35deg Cel. or higher is not that rare. I tried one just to get a feel and it did not exactly blow my hair back at 12V so I don't know.

I really don't want to scimp on the box but if I want see this thing cutting in the next few months I don't much of a choice. Its going to be incredibly hard to be patient while saving up for a box...