No idea why the motor turned off, it run ok tonight. Even managed to get the part finished.

Reduced DOC to 1mm, feed rate to 800mm/min and rpm up to 9000.

I think the issues may the cutter itself, not being designed for aluminium, just a standard two-flute slot drill.

Now i need to flip it over, align to the axes and find an accurate way of picking up the x&Y datums.