A bit is matched to a material
The single biggest mistake is using the wrong bit for what you’re drilling. A bit made for timber will skate off tile and burn out in steel. A bit made for masonry will make a mess of a clean hole in pine. Match the bit to the material and everything gets easier. Here’s what the names on the pack mean.
HSS — your everyday all-rounder
HSS stands for high-speed steel, and it’s the standard bit you’ll use most. It drills timber, plastic and softer metals like aluminium, and it’s cheap enough to own a full set without thinking about it. If a bit just says “HSS” with no other words, that’s your general-purpose, drill-most-things bit.
The catch: plain HSS goes blunt fairly quickly in harder steel, and it doesn’t love heat. Which brings us to the next one.
Cobalt — for steel and the hard stuff
Cobalt bits are HSS with cobalt blended into the steel, and the point of them is heat. Drilling into hard steel generates a lot of heat, and heat is what kills an ordinary bit — it goes soft and stops cutting. Cobalt holds its edge at much higher temperatures, so it keeps cutting through stainless steel and thick mild steel where a plain HSS bit would give up and start smoking.
They cost more, so you don’t need them for timber. But if you’re drilling into anything hard and metallic, a cobalt bit is the difference between a clean hole and a frustrated afternoon.
Titanium-coated — a middle ground, mostly
You’ll see gold-coloured titanium-coated HSS bits everywhere. The coating makes them a bit harder and helps them last longer than plain HSS in general use — they’re a reasonable upgrade for an everyday set. Just know the coating is a surface layer: once you sharpen them or it wears through, they’re back to being HSS underneath. For real hard-metal work, cobalt (which is hard all the way through) is the better spend.
Masonry — for brick, concrete and tile
Masonry bits look different: they have a wider, arrow-shaped tip, usually made of tungsten carbide, sitting on a steel shaft. That tip is built to smash and grind through brick, concrete and render rather than cut like a metal bit does. You use these with your drill’s hammer mode (the setting that adds rapid forward jabs) — the hammering does the breaking, the bit does the clearing.
Don’t try to drill masonry with an HSS bit; you’ll cook it in seconds. And don’t use a masonry bit on timber expecting a clean hole — it’ll wander and tear. For the occasional wall plug, a masonry bit and your drill’s hammer mode is all you need. For drilling masonry all day, that’s a different tool — a rotary hammer.
Spade bits and hole saws — for big holes
When you need a hole bigger than about 13mm, normal twist bits run out of puff. Spade bits (flat, paddle-shaped) bore fast, rough holes in timber — perfect for running cable or plumbing through studs. Hole saws cut a clean circle for things like door handles and downlights. Neither is fancy; both save you a lot of grief the first time you need a 35mm hole and realise your drill bits stop at 10.
Why your bits go blunt
Three reasons, in order: heat (drilling too fast, or in metal with no lubrication), the wrong bit for the material (see the entire guide above), and forcing it (leaning on a blunt bit makes it blunter, not faster). A sharp bit pulls itself into the work with light pressure. If you’re pushing hard and getting smoke and dust instead of clean shavings, the bit’s done — swap it before you wreck the hole or the bit.
What to buy
You don’t need a 200-piece kit. For most households:
- A titanium-coated HSS set in the common sizes, for everyday timber, plastic and the odd bit of metal.
- A handful of cobalt bits in the sizes you drill steel with — only if you work with hard metal (our best metal drill bit sets roundup has the picks).
- A small set of masonry bits for wall plugs into brick.
- A couple of spade bits and one hole saw in the size your next job needs.
Buy decent bits, not the cheapest ones — a good bit drilling the right material lasts for years, and a bad one frustrates you the first weekend. Worth knowing your rights, too: under Australian Consumer Law a bit set that shatters on its first proper use isn’t “wear and tear”, it’s a faulty product. Past that, replace bits as they blunt rather than babying them. They’re consumables. The drill is the investment; the bits are the petrol.
