Tile and Glass Drill Bit (12mm)

Everything that matters at the small sizes matters more here, because a 12mm spear point is removing four times the area of a 6mm one and generating heat accordingly. Run it slow, keep water on the tip, use light steady pressure, and never let the hammer action on.

There is one additional problem specific to the large sizes. A wide spear point takes a lot of getting started, and while it is establishing itself it wants to walk. Masking tape helps, but the better approach at 12mm is to drill a smaller pilot hole first with the 5 or 6mm bit, then open it out with this one. The pilot gives the point a centre to sit in, so it cannot wander, and it also lets some of the heat and dust escape rather than being trapped under the tip. It takes an extra minute and it is the difference between a clean hole and a cracked tile in the middle of a finished wall.

Twelve millimetre holes take pipework, cable bundles, tap and mixer tails, waste connections and large fixings through tiled surfaces.

If your work regularly involves holes at this size or larger, a diamond hole saw is faster and leaves a cleaner edge, since it cuts a ring rather than abrading away the whole disc of material.

YG6X cross carbide tip on a medium carbon steel shank, sand blasted finish, 1/4 inch quick release hex shank.

Buyers are plumbers, bathroom and kitchen installers, tilers, shopfitters and hardware dealers.

Ask on 94 77 111 8880 about the pilot sizes and whether a hole saw would serve you better. Delivered anywhere in the island.