Step Bit - (4-32)mm

A step drill bit stepping from 4mm up to 32mm. Instead of one diameter it carries a cone of successive steps, so a single bit drills any size in that range simply by how deep you push it - and it does so in thin material without the grabbing and triangular holes that ordinary twist bits produce in sheet. That makes it the electrician's and sheet-metal worker's favourite: knockouts in enclosures and consumer units, cable gland holes, holes in trunking, ducting and casings, and enlarging existing holes without changing bits. It also deburrs the hole as the next step passes through. Run it slowly with steady pressure, and stop at the step you want rather than pushing through - the steps are marked, but it is easy to go one too far.