Drills are one of the most convenient tools for DIY projects, but like all power tools, they must be handled safely. Knowing how to drill correctly will help you avoid injuries caused by fragments of broken materials that fly away or improper handling of electricity. If you ever have any questions that have to do with safety and that this guide does not respond, the drill user manual is an excellent option to consult.
Prepare to drill
- Wear safe clothing and eye protection. Avoid baggy clothes or hanging jewelry that could get caught in the drill while you lean over it. Wear safety glasses or glasses that cover your sides to protect them from debris that can fly away.
- Use ear protection if you will drill regularly. An electric hand drill produces about 90 decibels, which is enough to cause hearing damage after prolonged exposure. Most cordless drills are quiet enough that hearing protection is not necessary.
- Hand drills (or hammer drills) are the loudest, and they produce more than 100 decibels. It is recommended to wear hearing protection whenever they are used.
3. Protect your lungs when necessary. If the project raises a lot of dust, use some respiratory protection. A dust mask only serves for short-term comfort. Use a respirator mask if you are going to drill regularly or for long periods, or if the material you are going to drill carries a known respiratory hazard.
- Each respirator mask is classified for certain types of hazards. Make sure that the one you are going to use is suitable for the project.
4. Choose the correct drill bit. Using a drill bit made of the wrong material can cause the drill bit or the content you are going to drill to break. You can use a general-purpose drill in most woods; a masonry drill bit for stone, brick or concrete; an HSS (high-speed steel) drill bit in most metals and carbide or diamond-tipped drill on harsh and brittle surfaces, such as porcelain, glass or enameled tiles.
There are many specialized drill designs, so check the drill manual or the manufacturer of the drill if you are not sure which one to use.
- When drilling a hole for a screw, there is an easy way to find the correct size drill bit. Hold the screw directly under the drill. The drill must hide the screw shaft from view, but the screw threads must still be visible on both sides.
5. Place the drill bit firmly on the mandrel. The mandrel is the clamp on the “jaws” of the drill. This holds the drill in place while turning. To replace the drill, make sure the drill is turned off (and unplugged if it is wired), then loosen the mandrel by spinning it. Depending on the drill, you can do it by hand, or you may need the unique key for the chuck located in a compartment at the top or in the drill handle.  Insert the drill into the mandrel and then adjust it again. Verify that the drill is straight and secure and remove the key from the chuck before turning on the drill.
- Each mandrel has a maximum size. Most drills made for domestic use in the United States have a 1/4, 3/8 or 1/2 inch size chuck. The shaft of the drill should be smaller than this size (but the tip may be larger).
- Start the drill and watch the drill turn in the air. If it wobbles from side to side (or looks like a blurry cone), the drill is bent or not secured correctly. Discard curved drill bits as these can easily break when drilling.
6. Attach small parts with a clamp. If you are going to drill a little and loose piece, fix it firmly before drilling. Do not hold the article with one hand while drilling, as the drill could slip and hurt you.
7. Handle the cable safely. If the drill is wired, never leave it with the cord stretched in the middle of the road when not in use. Never lift the drill by the rope. If you are going to drill in a wet or muddy area, use a cordless drill instead.
- If you need to plug the drill into an extension cord, refer to the drill manual for the minimum wire gauge (or use a 16 gauge wire if you’re not sure).  Do not wire several extension cords together, do not use outdoor extension cords or use an adapter to plug a three-pin cable into a two-pin outlet.
- Drill a pilot hole. In many cases, you will get better results if you start with a bit slightly smaller than the size of the final hole. Drill a shallow “pilot hole,” then switch to a more massive drill to finish the job. The pilot hole will help you prevent the drill from sliding and reduce the possibility of wood breaking or other damage.
- Very fragile materials such as ceramics and glass require special care. Make a small “X” on the masking tape where you want to place the hole to avoid slipping and splintering. Instead of drilling the pilot hole, put the drill bit on the X, then tap it gently with a hammer to create a small dent.two
Drill with constant pressure. Hold the drill firmly and push it into the material you are drilling. If more than a light force is needed to drill the hole, you are probably using the wrong bit,
3. Adjust the clutch. Each drill has a rotating neck to adjust the torque, often with a series of numbers on it. The higher the number, the greater the torque (or rotational force) that the drill will apply. If you have trouble drilling in the material, the torsional force increases. If you are threading the screws (burying them too deep) or if you drill too deep, you could damage something, so reduce the torque.
- Some models mark the highest torque with the icon of a drill. 
Avoid overheating the drill. If you are going to drill through hard materials or drill at high speeds, the drill will be immensely friction. This can overheat it quickly, to the point where it turns red hot or burns the material you are drilling. Start drilling at low speeds and only increase it if the drill does not move smoothly. If you are going to drill through hard materials, or make many holes in any content, stick to slow speeds and occasionally pause to let the drill cool for a few seconds.
- When drilling glass, ceramics or stone, give the drill a constant supply of water to keep it fresh. One way to do this is to build a “dam” with putty or clay around the area where you are going to drill. Fill the space with water to flow into the hole. “Pump” the drill up and down so that the water can reach the tip.
- Even if the drill does not appear to be hot, give it time to cool before touching it.
5. Do not force a jammed bit. If the drill bit gets stuck in the material, do not try to force it by starting the drill. Unplug the drill, separate both the drill and the chuck, and then remove the drill using hand tools.
- Many drills have depth gauges that you can configure to avoid drilling too deep. If yours doesn’t have it, measure the depth you want from the tip of the drill and glue a piece of tape to that depth.
- Before drilling into a wall, use a beam detector with configurations that can detect electrical pipes and cables. In most modern homes, the wires pass near both the floor and the ceiling, and these only moves vertically when they go directly to the plugs and lighting fixtures. However, there are no guarantees that the house has been built according to this code, and an unexpected accident could be potentially fatal. If you want to be safer, turn off the power from the circuit box before drilling or install a ground fault circuit breaker (GFCI), also called a differential switch (ID or RCD). This will automatically turn off the electricity if you run into a wire.