Ah thanks for that Dean, I'll retry with level 3 and see if that works. It should work as it wasn't the usual chip weld, but rather the spindle went into "DU" which is an Amp overload iirc

My F&S's were F2760mm/min and 17,642rpm - GWizard generated with HSM and roughing options checked.

The whole video (once I've finished editing) has 6 and 4mm tools cutting fine with similar strategies - the 6mm was at 10mm DoC, which was frankly astounding considering previous experience.