3.5mm drill bit
Ideal for drilling holes for M3 screws with ‘wiggle room’
I’ve found that 3.5mm is the best size for making holes to mount turret boards to a chassis, even with M3 hardware. A 3mm hole is theoretically correct, but often makes perfect alignment tricky. Perhaps the lack of ‘wiggle room’ means that temperature changes and different expansion factors for aluminium and phenolic/PTFE create tolerance problems? For sure, the extra 0.5mm really helps.