Drill Bits

The bit is chosen according to the material. For metal you need high-speed steel (HSS) bits, for masonry masonry bits with a carbide tip, and for wood bits with a centre point. Multi-material bits, such as the krino, cover several materials but do not replace a specific bit for frequent work. Always check the material shown on the packaging.

HSS bits are made of high-speed steel and cope well with the heat produced when drilling metal. The rolled HSS bit in the collection, in the Metal Werk version, is designed for holes in metals. Bits with a reduced cylindrical shank are used in standard chucks. For drilling steel it is best to use a cutting lubricant and a low speed, so as not to damage the cutting edge.

Step drills, including carbide (HM) ones, bring a hole to the diameter you want without changing bit. Conical cutters and conical hole-enlarging tools, such as those in the Fervi A014 series, cover ranges of different diameters shown on the tool body. For thin sheet, work with light pressure and at low speed. Check the scale engraved on the tool for the diameter to be obtained.

Three-flute countersinks create the conical seat for the head of a screw or rivet. The number of cutting edges helps to produce a more even surface. Work at low speed and with light pressure, because the bit can wander across the surface. If possible, first drill a centred pilot hole. Clear the swarf often.

An assorted bit set gathers different diameters in one pack, useful if you drill many holes of different sizes. The set of 19 bits and inserts from Ingco also includes screwdriving inserts. The 16 or 19-piece sets in a plastic case are handy for DIY and small workshops. It is still worth having a specific bit for the material you use most, because the set does not cover every case.

The adjustable sheet hole cutter drills from 20 to 123 mm in laminates and metals, and is suited to panels and thin sheet. The HSS conical cutter and the conical hole enlarger are for sheet of limited thickness. For the diameter, choose the tool whose range covers the size you need. Always drill a small centred pilot hole first.

Speed is chosen according to the material: lower for metal and steel, higher for wood, with suitable bits. Pressure should be steady and not excessive, so as not to overheat the bit. For steel, use a cutting lubricant. When the bit smokes or changes colour, stop and cool the hole. Clear swarf from the hole often.

For wood, use bits with a centre point and a side cutting edge, which make a clean hole. HSS bits are also fine for wood, but for precise holes a centre-point bit is better. In assorted sets you often find wood bits, to be used at higher speed. Keep the bit sharp, because a blunt edge heats up and burns the wood.