I just carried on as per normal instructions as if it was aluminium. I didn’t even think about it. I always use a lubricant like Boelube with anything steel though. Same with the rivets. They squeezed just like aluminium. For my setup, and I stress for my setup, I have found that the slowest speed on my drill press 335 rpm and quite a high feed rate reduce the chances of chattering when machine countersinking.
Last edited by Vakashi : 02-19-2018 at 06:00 PM.
Reason: Added a thought