More interesting advice!

The comment about thin ali sheets being soft makes a l;ot of sense, and I shall try to get some 6061
You are correct that the 1mm cutter is Chinese - I got them because a set of 10 was cheap, and I assumed that in trying to find out what cutting speed/feeds were needed I would be snapping a lot of them. The spindle is a cheap 775 motor, which seems good for speeds up to around 16.500 rpm and has lots of torque at 36V.

If the calculators recommend 100mm/min at 10,000 for a 1mm mill, would it be reasonable to lower the revs and lower the feed speed, or is 100 a figure I should stick with? it seems rather fast to me.....