If you’re in the market for a drill bit for a particular job, then you might find yourself overwhelmed by the sheer breadth of options available. There are a lot of different sorts of bit out there, and it might not be obvious which one is appropriate for your particular needs.
Let’s examine the options, and see what the key differences are using insight provided by SGS Engineering.
The generalised bit that just about everyone should have access to are shaped like a helix. The point for the drill, called the spur, is driven into the material, and the spiralling ‘flutes’ provide room for the excess material to be pushed from the hole. More expensive bits are made from carbon steel, with protective coatings of titanium nitride, which help to protect the bit when drilling through metal.
By varying the materials, we can create more specialised bits. For example, if you’re drilling through masonry, then look for a masonry bit. In shape, they’re the same as a multipurpose bit, but they use more specialised materials, which maximise the cutting potential while damping vibrations.
Among the more eye-catching types of bit are spade bits. These come with a fine spur sprouting from the middle of a flat paddle, with sharp corners on each end. These are designed for creating big holes in a piece of wood. The idea is that the spur in the middle will bite into the wood, allowing the metal on either side to quickly chew through the surrounding wood. While these are great for creating big holes quickly, they do risk causing splintering. They’re great for outdoor applications, such as holes in wooden posts that need to be threaded.
Salt Feed bits work via the same principles – except rather than a spade, it’s a sort of rotating disk which surrounds the spur.
These bits look just like multipurpose bits, except they come with a sharper spur that’s easier to keep fixed in position. Augur bits are designed to make holes in wood, much like spade bits – except these produce much neater holes. They’re thus often used by furniture-makers looking for keep up appearances.
The choice when it comes to driver bits tends to be a great deal more self-explanatory: simply match your bits to the head of the screw you’ll be driving. So why are there so many different kinds available? It’s all to do with the torque required for the particular job. When the torque exceeds a certain level in a Philip’s-head screw, it’ll tend to ‘cam-out’, slipping from the niche. Of course, you can get around this by repeatedly driving the same screw, but then you’ll risk overtightening.
Slotted, Philips and Hex account for the overwhelming majority of screws you’ll be driving. Certain applications might demand square or star-shaped drivers, however, so your choice will tend to depend on the work you’re doing. The advantage of these more specialised bits is that the level at which they ‘cam out’ tends to be far more consistent – which is super-helpful when the bit is rotating at extremely high speeds. A selection of various different bits should be sufficient to tackle most tasks, though you may need to invest in specialised bits of different sizes in order to cover every possibility.