This time phlux.co.uk done another window and a stealth blowhole in their Chieftec Silver Dragon.
I enlarged the size of my pilot hole until it was just a bit smaller than the drill bit on the arbor. As a lot of friction and heat is created when the holesaw cuts through the metal you can get burn marks on the metal. To prevent his spray the area you are going to get with oil like WD-40. Also spray the holesaw.More information at phlux.co.uk