A power drill seems like a pretty straightforward tool. You pull the trigger, the bit spins, and you get a hole. And yet it’s easy to go wrong. Or rather, it takes a bit of practice and know-how to get a perfectly cut hole, every time. Today we’re going to check out some hole-drilling basics, a little bit of terminology, and some very handy tips.
A drill’s bits
A drill consists of a few sections. There’s the main unit, the part that usually looks like an oversized pistol. There’s the trigger, which sets the unit running. Then there’s the chuck, which is the big metal cylinder on the front, the part that holds the drill-bit and spins. The drill bit is the interchangeable part that does the actual cutting. There are many types, and we’ll see a few of them below, but most bits work the same way: The spinning tip cuts a hole, and the spiral channel removes the dust and debris from that hole.
Also important is the chuck key. This is used to tighten and open the chuck. Most modern, cordless drills don’t have one, but there’s one infallible truth about the chuck key—you will misplace it more than you misplace any other tool, ever. So, the first tip is to keep the key in the little rubber holder on your drill, if it has one.
First, some safety tips:
- Always unplug the drill before touching the chuck or the bit.
- Never change the bit with the drill connected to power. If your drill is battery powered, you should, at the least, engage a safety lock before swapping bits or adjusting the chuck.
- Don’t touch the bit after use. It will be very hot.
When drilling walls, make sure you know where power lines or pipes run. Usually, but not always, power cables run vertically or horizontally from switches and outlets. If in any doubt, don’t drill. And if possible, switch off these circuits at the fusebox.
Hidden water pipes and hoses are less common, but in bathrooms and kitchens, you should remain aware of them. A good habit is to take a step back from the wall and look everything over before you start.
How to fit a bit
There are a zillion different kinds of drill bit, but the most common are:
- Masonry bits, for drilling walls.
- Wood bits, for—you guessed it.
Always match the bit to the material. The sharp cutting tip of a wood bit will be blunted immediately by brick. The hardened, blunt grinder at the tip of a masonry bit will do nothing but butcher wood or metal. If in doubt, ask the person at the hardware store. There are also general-purpose universal bits, which are convenient, but often don’t perform as well as a dedicated bit.
To fit a bit, open up the chuck by spinning its collar (counter-clockwise, lefty-loosey), which will loosen the jaws within. Close the chuck so that its three jaws are roughly the correct side for your bit, insert the bit, and tighten. You may have to jiggle the bit to make sure it sits straight in the jaws. If your drill has a chuck key, insert it after the chuck is hand-tight, make sure the teeth are engaged, and tighten. You can press the drill trigger very lightly, to verify that the bit is spinning true and not out of alignment.
For keyless chucks, follow the instructions for your drill, but usually you just tighten everything by hand.
Drills may have a hammer action, a speed adjustment, and a reverse function.
The hammer action is for faster drilling into hard masonry. It hammers the bit in and out as you drill. This is a lot faster then brute-forcing it yourself. It is also very noisy, and makes it harder to start a hole accurately. Use only when necessary. If you are using the hammer action, start the hole without it, pause, then engage before continuing.
Speed should be matched to the job. Faster speeds drill faster, but also heat up faster, and if you make a mistake, things will go wrong a lot faster and screws are more likely to get stripped. You should use a slower speed on wood, for example, otherwise you risk burning it1. Some drills have separate settings for speed. Others modulate speed based on how much you pull on the trigger.
You will usually also find a forward/reverse switch near the trigger. The reverse function is used to help remove the bit if it gets stuck in the hole, and also to unscrew screws if you’re using a screwdriver bit in your drill.
When you drill a hole, you want it to be in the right place, at the correct angle, and to the correct depth.
One way to get the hole in the right place is to just be careful, resting the bit on the mark, holding steady, and starting the drill off slow. Any bit that has a small spike at the center of its tip makes this easy.
Another trick is to make a smaller pilot hole, to help locate the bit when drilling the final hole. This pilot hole should be shallow, and can be made with either another drill bit, or by using a bradawl (a hole-making tool that looks like a sharpened screwdriver).
To get the hole square—not its shape, but its angle—just be careful. Line it up by eye with the drill bit’s tip resting on the wood/wall/metal. If drilling into a wall, pay extra attention to the vertical alignment. It’s easy to let the handle-end dip, resulting in an upwards-pointing hole. To mitigate this, crane your body and head out to the side to check, or have an assistant check for you.
The last dimension is depth. Some drills come with an adjustable depth gauge. Some drill bits have a tight-fitting plastic collar that can be slid up and down the shaft to mark the correct depth. Failing that, a scrap of masking (painter’s) tape can be wrapped around the bit to mark it.
If you’re drilling to place a drywall anchor, make the hole a little deeper than the plastic plug you’ll be inserting into it. Otherwise, start off shallow, and go further only if you need. For finer work—wooden furniture or shelves, for instance, the risk is drilling through to the other side of the plank. You don’t want holes peeking through your tabletop, for example.
Related to this last point is something called tear-out. If you drill through a piece of wood, when the bit reaches the other side, it can rip out chunks and splinters as it exits. One workaround is to drill to the perfect depth, so only the sharp tip of the bit protrudes. Then, using the hole left by this tip as a pilot, finish the hole by drilling back in from the reverse side.
An easier way to prevent tear-out is to clamp a second, sacrificial, piece of wood to the back of the first.
The amazing, life-changing coffee filter trick
I’ve saved the best tip until last. I only learned this a few years ago, and it has changed my life.
When you drill a hole in a wall, you get all kinds of dust—brick, plaster, stone, cement. It spreads everywhere; red brick dust, especially, can mark a white wall. So, use painter’s tape and stick a paper coffee filter to the wall, directly below the soon-to-be hole.
Pull the filter open, so you have a small paper basket ready to catch the dust. Use an old paintbrush to brush off the wall above the filter before removing it. This trick really is quite a timesaver, and means that you don’t have the clear the entire area before the job, or spend much time cleaning up after.