Drilling a hole in concrete is a practical and useful technique; in this way, you can install shelves, hang pictures or lights proceeding with greater safety and speed. The job is pretty simple, but by choosing the right tools and learning how to use them, you can save a lot of time.
Steps
Part 1 of 2: Preparation
Step 1. Purchase or rent a pneumatic drill
It's much easier to drill into concrete with this tool or use a demolition hammer for the toughest jobs. These tools break the material with rapid pneumatic pulsations and then drill it to remove the fragmented cement. A normal drill takes more time and effort, as it is not as easy to penetrate the concrete layer by layer as it is with wood or metal. Consider paying a little more to rent a demolition hammer for any job that is more challenging than a few holes in non-load-bearing structures (such as brick kitchens that are made with a softer blend).
Generally, it is worth spending a little more on more powerful tools (at least 7-10A) from well-known and trusted brands. Other useful features are the ability to set the speed, automatic lock at the default depth, a good grip and the presence of a second handle for the other hand
Step 2. Get familiar with the tool
Read the instruction manual and learn to recognize the use of the various knobs and controls; make sure you know how to handle it before moving on to the next steps.
Comply with all safety regulations. This means wearing protective goggles to prevent concrete chips from getting into the eyes, using hearing protectors, putting on work gloves to protect your hands from abrasions and contact with the hot tip; We also recommend using a respirator for projects that last a long time and generate a lot of dust
Step 3. Insert a high quality concrete drill bit
Carbide drills are made for pneumatic drills (they are sometimes labeled "percussion") and are capable of withstanding the pressure required to hammer and penetrate compacted concrete. The grooved portion of the tip should be at least as long as the hole you plan to make, as it is critical to expelling dust from the hole.
- Demolition hammers need special drills called SDS or SDS-MAX (for holes with a maximum diameter of 15mm) or Spline-Shank (for holes of 18mm or larger).
- Reinforced concrete is much more difficult to drill if you have to go through the steel reinforcement; if so, switch to a special drill that can sever the metal when it encounters it. Slow down and stop from time to time to avoid overheating.
Step 4. Set the depth
Some models are equipped with a self-locking system that activates once the required depth is reached or a bar that acts as a thickness to obtain the same result; in these cases, read the instruction manual to know how to use them. If the tool you are using does not have this feature, make a mark on the tip to the required depth using a pencil or a strip of masking tape; if you don't know how much you need to drill, follow these directions:
- Since concrete is a dense and hard material, screws inserted at 2.5 cm are enough to hang light objects; for more demanding projects you need longer screws or dowels whose packaging shows the depth of insertion.
- Add another 5-6mm of depth to account for dust accumulating during drilling. If you plan to clean the hole of all debris, you can skip this step instead.
- To drill into hollow concrete blocks or thin surfaces you must follow the instructions on the packaging of the screws or dowels. Some particular types of small parts can only be anchored to solid blocks and could fall if all the material goes through to the other side.
Step 5. Grab the drill correctly
Grab it with one hand as if it were a pistol by keeping your index finger on the "trigger". If the tool has a second handle for the other hand, use it; if not, place it on the back of the drill.
Part 2 of 2: Drill the concrete
Step 1. Make a mark on the point to be drilled
Place a reference mark on the wall using a specific soft lead pencil and draw a point or a small cross.
Step 2. Drill a pilot hole
Place the tip on the traced mark and drill briefly at low speed (if the tool has a regulator of the same) or with several rapid pulses (if there is no speed control); drill a shallow hole (3-6mm) to guide the tip and create the actual opening.
If you need a large diameter drill for the project, consider using a small drill bit for the pilot hole to improve the stability of the tool
Step 3. Continue drilling while increasing the power
If your instrument has a percussion function, turn it on. Place the bit in the pilot hole, hold it perfectly perpendicular to the surface and start drilling with firm but not excessive pressure. Gradually increase rotational speed and strength as needed, but make sure the tip remains steadily stable and under your control. Concrete is not a homogeneous material and the tip could easily slip if it encounters crushed stone or an air pocket.
Apply enough pressure to hold the tool in place, but do not force it into the material, otherwise you will increase the wear on the tip and may even break it; with practice you will learn how to use the right force
Step 4. Pull out the tip from time to time
Back it up slightly every 10-20 seconds to get some dust out of the hole.
Stop occasionally and remove the tip from the surface to allow it to cool for a few seconds. This step is very important when using a regular pneumatic drill, as it can easily overheat in the process
Step 5. Drill through obstructions with a masonry nail
Sometimes the drilling does not go as expected; if you come across a particularly hard piece, insert a masonry nail into the hole and hit with the hammer to break the block. Be careful not to penetrate the nail too deep to be able to extract it without problems; then bring the drill bit back into the opening and continue the work.
If you notice sparks or metal fragments, you are faced with a reinforcing rod; immediately stop the drill and switch to a special bit until you have overcome the obstacle
Step 6. Blow the dust away
In this way, you improve the anchorage of the dowel in the material. Use a bulb syringe or can of compressed air to get rid of any residue; when finished, clean everything with a vacuum cleaner. During this phase, do not remove the safety glasses, in order to protect the eyes from dust and debris.
Advice
- Ask a person to hold a vacuum cleaner hose (or half a paper plate taped to the wall) just below the hole you are making to save time for subsequent cleaning.
- If possible, insert the screw into the mortar between the concrete blocks, as it is easier to drill into this material than the blocks themselves; in this case, always use a metal dowel, because the screws inserted directly into the mortar over time crumble the material and lose their grip. Plastic anchors (with normal screws) or self-tapping screws for concrete (without anchors) can be used to install lightweight elements such as electrical boxes or metal conduit collars. Self-tapping screws are easy to recognize because most of the time they are blue in color. For all other jobs where the screws are subjected to a heavy load (such as a bench, a shelf or a handrail) it is better to rely on screws with sturdy and metal plugs that must be inserted into the holes with the hammer; the screws are then screwed into these "anchors".
- Professionals use a diamond-tipped core drill to drill larger holes than can be achieved with electric demolition hammers. The choice of the tip depends on the characteristics of the concrete, including the thickness and hardness, the curing times and the presence of reinforcing metal rods.
Warnings
- The older the concrete, the harder it is to drill into it.
- Do not press the drill with all your strength, otherwise the bit can break.
- Carbide tips can shatter when they come in contact with water. If you want to use this liquid to prevent overheating and minimize the spread of dust, read the instructions accompanying the tip or contact the manufacturer to find out how to proceed safely. When using water, be careful not to get the drill motor wet.
