The Power Tool Diagnostic: What You Should Know About Drill Bits

If you’d like to drill a hole in something, then you’ll need to take account of the material into which you’ll be drilling, and choose a drill-bit that’s appropriate for the task. Bits come in a variety of shapes, sizes and materials, and what works well in one instance might not work quite so well in another.

How does a drill bit work?

A drill bit is actually quite an intricate piece of machinery, despite the fact that it’s just a single piece.

The tip of the drill is called the spur. It’s this bit that first meets the surface – but it doesn’t actually do any cutting. It simply holds the drill into place while the cutting lips rotate around it. These are the edges to either side of the spur.

Further back, the drill turns into a metal spiral, comprising ‘flutes’ and the spaces between them. These provide a channel through which displaced material can actually be pushed back out of the hole. Without flutes, a drill wouldn’t be able to work – it would just squash the material inside. Finally, at the rear of the bit there’s a shank – a plain metal cylinder to which the drill actually attaches.

It’s by varying the size and shape of these various components that we can adapt the drill to a particular type of material. If you’d like to learn more, why not check out a comprehensive guide to drill bits? In the meantime, let’s check out a few common types of bit.

Standard Bit

These are the all-rounders which are suited to a range of purposes. They can cut into plasterboard, into metal, and into wood – and they’re cheap, too.

Masonry Bits

Drilling through a brick wall requires a more rugged type of drill bit. The tip of a masonry bit tends to be coated in tungsten or some similarly hardy kind of material. It will protect the metal behind it against the abrasive effect of repeat drilling. Pair it with a hammer-action drill.

HSS Bits

If you’re drilling through metal, you might find that the drill bit quickly becomes incredibly hot. There’s a lot of friction, here! High-speed steel bits are able to cope with these high temperatures a lot easier, and thus they’re perfect for those looking to drill through metal again and again.

Augur Bits

These are suited to making precisely-positioned holes in wood. They come with a sharp spur that’ll dig into a soft surface, and sharp edges that’ll produce a neat hole.

Spade Drill

If you want to quickly make a large hole in wood, then you need a drill bit whose cutting lips are further apart. That’s a spade drill bit. They don’t have any flutes, which makes them suited only for drilling shallow holes through planks of wood.

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