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How to Drill Through Aggregate Concrete (Tips and Techniques)

how to drill through aggregate concrete

Drilling through aggregate concrete isn’t so hard when you know the right way to do it. We’re going to dive into the best tips and techniques to make your experience smooth and stress-free. After reading this article you should be able to drill through any aggregate concrete safely and efficiently.

Safety Warning

Before getting started it’s important to point out a quick safety warning. As you drill through concrete there are a few hazards you should keep in mind.

First, bits tend to get stuck. When they’re stuck, often the drill will spin around the bit. This means that you should avoid drilling on a ladder, raised platform, or leaning over a surface. This can result in you falling.

Also, drilling can kick back some dust and chunks of aggregate. You should always wear a respirator and safety glasses, so you don’t wind up in the hospital.

Getting Started

There are some tips and techniques that make the process easier. A lot of it has to do with getting started and understanding different ideas. Let’s highlight some of the important lessons you should learn before picking up the drill.

Getting the Right Tools

You don’t use a screwdriver to hammer a nail. In the case of drilling through aggregate concrete, using the right tools and bits is arguably the most important step.

A lot of people like to use hammer drills for concrete. In fact, the tool was specifically designed to punch through concrete.

You’ll get the same drilling action that you’re used to, but hammer drills will also vibrate and punch with the bit. This does a great job of breaking up aggregate while it drills through.  

Using the Right Bit

In the world of concrete, there’s a whole class of specialized bits that will help you. They’re called masonry bits and they’re typically carbide-tipped. They are designed specifically with concrete in mind, and the right bit will go a long way.

Make sure that the bit you choose works in the drill you have. Some masonry bits won’t fit in a standard drill chuck, and others aren’t compatible with hammer drills.

Get Ready for Dust

Dust is going to be a big factor when it comes to drilling. The dust will clog your bit, overwork your drill, and make a mess.

It’s important to regularly back your bit out of the hole and blow the dust with canned air. Keeping a low amount of dust will make for a great experience.

Additionally, the dust can cause things to bind and overheat if you don’t clear it often enough.

If you’ve got a shop vac, keep it near by. Or you could even keep the shop vac turned on and leave the end of the hose lying next to the spot that you’re drilling.

Remember the Pressure

Using a hammer drill is less about using as much pressure as possible and it’s more about keeping a constant pressure. Allow your tool and bit to do all the work, you’re just there to guide it and give it a gentle push along the way.

Big deviations in pressure can ruin the hole and get your bit jammed, so just be careful.

Using Water

A lot of people like to use water while they drill. It prevents dust buildup and helps everything cool down and avoid overheating.

Industrial concrete drills even have a water system built into them, so that’s a good indication that it really works. For your application, you might use a garden hose depending on the location and area of drilling.

Consider a Shop Vac

Some people like to hold a shop vac up to the hole that they’re drilling. It helps collect the dust and saves you some time later.

Know the Depth

Know how deep you want to drill the hole. If your drill doesn’t have a depth control bar, mark the depth on your drill with a piece of tape.

You don’t want to drill too deep or shallow and ruin the project.

Jams Might Happen

Be prepared for jams. Your bit might get stuck while you’re drilling and that’s something you have to plan for.

There are ways to get a broken or jammed bit out of concrete, so there’s no need to freak out. Just make sure you’re not promising an aggressive timeline that will get ruined with a jammed bit.

How to Drill Through Aggregate Concrete

Now let’s get to the fun part – it’s time to start drilling!

Step 1 – Mark It

Start off by marking the location of the hole. Use a dot, a cross, or a crosshair. You want to make sure the exact point is indicated, so you should avoid making a thick bubble.

Using a punch to mark the center typically doesn’t work well with concrete drilling since some hammer drill bits are blunt-tipped anyway.

Step 2 – Start the Hole

With your correct bit and tool, start drilling. Use a low speed if it has a variable motor, or punch the hole with short bursts if it doesn’t have one. You just want to make a 1/4 deep hole to get you started.

You might want to use a smaller bit for this step. This is just the start of your hole so that your real hole doesn’t walk or creep and it stays straight.

Step 3 – Get to Drilling

Now it’s time for the real drilling. Put in the right bit, throw your drill on hammer setting, and get to work. Don’t forget to apply constant pressure, use water when applicable, and routinely back out your drill and blow out the dust in the hole.

Step 4 – Clear Obstructions

If your bit gets bogged down at all, that means there’s an obstruction. In most cases, it’s a chunk of aggregate.

Use a long masonry nail and a hammer. Give it a few good whacks to dislodge the obstruction. If you see sparks, that means that there’s some rebar in there. You’ll want to use a rebar-cutting bit now if you have one.

How to Drill Through Aggregate Concrete Without a Hammer Drill

Since you won’t have the added strength and effectiveness of a hammer drill, you’ll have to use a little more finesse.

Start with a small masonry bit in your drill. Keep your hands steady and apply constant pressure on the drill as you drill the hole. If you feel an increase in pressure, back out of the hole and go again.

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When the hole is the desired depth, grab the next largest masonry drill bit and repeat the process until the desired hole diameter is drilled. Make sure not to step up by more than 1/8 of an inch.

If your bit can’t go any further, then there’s a little hack. Go up a size for your drill bit and drill to the same area. Put a hardened nail in the area and give it a few hits with a hammer. This will help break up the aggregate. Go back to your smaller drill bit and continue on.

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