Steel Bit - (3.5mm)

A 3.5mm twist drill bit for steel and other metals. Half-millimetre sizes exist because fixings do not come in round numbers: 3.5mm is the pilot for some self-tappers, the tapping hole for certain small threads, and the clearance hole where 3mm binds on the screw and 4mm leaves it sloppy. On sheet metal and light bracket work that slop is the difference between a fixing that pulls up square and one that sits at an angle. Also used for rivets, cable cleats, instrument panels and repair work. Hammer action off, moderate speed, and a centre punch mark to stop the tip skating across the surface. Ease off as it breaks through - fine bits snatch and snap at exactly that moment.