Step & Cone Drill Bits

Step and cone drill bits let one bit drill a range of hole sizes, and this guide explains how they work and when to use them.

How a stepped drill works — A stepped bit is machined into progressively larger diameters up its length, so pushing it further through the material opens the hole to a bigger size. One bit covers many hole sizes, which saves swapping drills and keeps a set compact. The stepped point is self-starting and needs no pilot hole in thinner material.

What they suit — Step and cone drills are at their best in sheet metal, panels, box section and plastics, where they cut clean round holes and deburr the edge as they go. They are the quick way to open cable-gland, grommet and fixing holes to size. They are intended for thinner materials rather than deep holes in solid stock, where a standard twist drill is the right tool.

Getting a clean result — Run at a steady speed, ease off as the bit breaks through, and use a cutting lubricant on metal. Working up one step at a time gives the cleanest hole and protects the cutting edges.

For the full range of high speed steel drills, see our HSS Drill Bits collection.

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