How to choose drill bits: metal, wood or masonry?

The right bit depends on the material you need to drill: HSS or cobalt for metal, a brad-point bit for wood, carbide for brick and stone, a diamond or spear-point bit for porcelain stoneware. Then check the shank: straight for the chuck, 1/4" hex for drivers, SDS-Plus for rotary hammers. In this collection you will find single bits and assorted sets, with diameters from a few millimetres up to about 60 mm for step drills.

The types

• HSS metal bits: high-speed steel bits for iron, steel and aluminium. Some have a taper shank (taper tool) for the drill press.
• Cobalt bits: for harder steels and stainless steel, like the cobalt bits in the catalogue.
• Step drills: a stepped cone that makes holes of different diameters with a single tool, ideal on thin sheet metal. In the collection they cover ranges such as 3-14, 6-20 or 40-61 mm, for example the HSS step drill bits with hex shank.
• Multi-material bits: they do several jobs with a single bit, like the multi-material bits in the catalogue. They are practical for mixed use, but less effective than a dedicated bit.
• Masonry bits: carbide, also with an SDS-Plus shank for the rotary hammer. They are used on masonry and concrete.
• Tile bits and bits for porcelain stoneware and ceramic: for drilling porcelain stoneware, tiles and stone, like the tile bits for porcelain stoneware.
• Bit sets and assortments: assortments of 5, 6, 10 or 19 pieces, useful if you work on different materials and diameters. The collection also includes a countersink kit, the 6-piece countersink kit art. 01270.

How to choose by job

The features to look at

• Material: the data sheets list HSS, HSS-G, super high-speed steel, carbide insert, hard metal (widia) and ceramic. HSS works metal; carbide (hard metal) is for brick and stone.
• Shank: straight shank for normal chucks, 1/4" hex for drivers, SDS-Plus for rotary hammers, M14 for the cutters and core bits mounted on a grinder. If the shank is not compatible with the machine, the bit is useless.
• Diameter: for sets you will find lists such as 4, 5, 6, 8, 10 mm or 6, 8, 10, 12 mm; for step drills a range, such as 3-22 or 16-30 mm. For holes in walls the diameter must match the wall plug.
• Overall length: from a few tens of mm up to 610 mm. A long bit is needed for large thicknesses, but it must be rigid enough.
• Packaging: from 3 to 19 pieces. A set costs more than a single bit, but avoids downtime when you are missing a size.

Common mistakes

• Using hammer action on an HSS bit. The cutting edge is ruined. Hammer action is only for masonry bits.
• Drilling tile with hammer action. The glaze chips: drill in rotation only, starting from a template.
• Speed too high with large diameters. The bit overheats and the hole does not come out round.
• Choosing a shank that the drill does not accept. An SDS-Plus bit does not fit in a normal chuck.
• Not clearing the chips. In deep holes the bit is withdrawn several times, otherwise it jams.

Frequently asked questions

Is a multi-material bit good for everything?

No, it is a compromise. It is fine for mixed jobs on materials of medium hardness; for hard metal or reinforced concrete you need the dedicated bit.

When is a step drill worthwhile?

When you have to make holes of several diameters in thin sheet metal. With a single tool you avoid changing bits.

What is the SDS-Plus shank?

It is a slot-in shank for rotary hammers that leaves the hammering movement to the bit. It is used for holes in walls and concrete.

Is a set or a single bit better?

A set is fine if you change size often. If you always make the same hole, the single bit is cheaper.

To choose among the more than seventy bits and sets, look at the drill bits collection, or request a quote or ask the AMES technicians for advice.