Chinese 2.2 water cooled spindle / Which VFD ?

[Jonathan]

is that the same bit for "rough cutting" and "finishing" or is there no such thing on Alu ?

Yes, for roughing use it at whatever the maximum depth the machine will tolerate is, but leave the part 0.1-0.2mm oversize. Next do a finishing pass the full depth in one cut, which just removes the 0.1-0.2mm.
13000rpm @ 600mm/min is a good speed for the 6mm single flute tool. Start with a smallish depth and work up, keeping the feed and speed the same, until you find the limit of the machine/cutter.

Roughing cutters do exist for aluminium. They have a serrated edge which is designed to break the swarf up into small pieces which can easily be washed away by flood coolant.

[dudz]

What do I use for drilling and countersinking Alu?... seems a daft question. I want to make a new Z plate soon, to hold the Chinese spindle, as the one on the machine is only 100mm wide. The spindle holder for the Chinese one is 140mm wide. So I need to accurately drill the holes for mounting on the machine and for the spindle holder. Links on ebay would be fantastic if poss.