Drilling in Masonry or Rock? Use a Masonry Drill Bit. (2024)

To make a hole in masonry and rock, you need a masonry bit—and to know how to use it in the correct way. It might not be often that you actually need to do this, but the task crops up every once in a while, as we’re experiencing now that the shop floor is done in the new Popular Mechanics office and we set about building and installing all the equipment we need. The shops’s floor is concrete, and the walls concrete block.

Get masonry drilling right, though, and a tough job becomes a lot more predictable, with the desired results: a round hole made to the proper depth without breaking the bit or burning out the power tool.

Here, we lay out the clever engineering behind these specialized drill bits as well as how you can best use them in your projects.

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A Carbide Tip Makes The Bit

You use a masonry drill bit in a specialized drill, called a hammer drill (such as a cordless drill driver with a hammer function) or a rotary hammer. These bits are similar to those for making holes in wood and metal in that they’re cylindrical with spiral flutes along their length. However, masonry bits have a piece of tungsten carbide (a composite material consisting of tungsten and carbon) brazed to the tip. The carbide is extremely tough and wear-resistant, enabling the bit to hammer its way through masonry or stone. Masonry bits are available in various diameters and lengths, and we recommend these from DeWalt.

Industrial-duty masonry bits for making deep holes in concrete may have multiple pieces of carbide brazed at the tip in an X Shape. Or the entire tip of the bit may be carbide, as it is below on the MX4 rotary hammer drill bit from Milwaukee.

Other Variations

There are multi-material bits that can drill in all common construction materials except for glass. They are most commonly used to drill in wood and masonry. One example is the MP500 bits from Bosch. I own a set of them and find them indispensable for making holes in wood, concrete, brick, and mortar. In a pinch, I even use them in steel. I employ them in my hammer drill but also in my impact driver.

To use them in an impact driver, you insert them as you would any other hex shank bit. To use them in a drill driver, you tighten the chuck on them as you would a bit with a round shank. Note: Don’t use your impact driver to make holes in masonry, which could burn it out. Chuck these multi-material bits into a hammer drill instead to make a hole in brick, concrete, concrete block, mortar, or stone.

Keep in mind that these bits are jacks of all trades but masters of none; they allow you to switch quickly between drilling in a variety of materials and driving fasteners in those same materials. You can use them to make holes wood of any thickness, but I’ve found them to be not particularly effective in thick steel; I limit their use to light-gauge metal, no more than approximately 3⁄16-inch thick. There are better and faster ways to drill steel, and even wood, but you’ll find that an impact driver works well with these bits to make small-diameter holes in thin material. If, in the course of the same job, you need to punch a hole in masonry, just pop the drill bit out of your impact driver and chuck it into your hammer drill.

The German SDS

The so-called SDS bit is widely used in the United States today, but it was developed in Europe, which uses more masonry materials in residential (and commercial) construction than the U.S. The Europeans developed a specialized subset of masonry bits that provided for rapid change out, either because the bit became dull or to switch to another size. SDS is a German acronym for Streck-Dreh-Sitz, or “stretch-turn-seat,” a reference to the first generation of these bits and how they were intended to be inserted in a rotary hammer’s chuck.

The Americanized version of the acronym remains the same (SDS) but is understood to mean Spline Drive System or Slotted Drive System, perhaps a better description of these bits and how they are held in the chuck, not by tightening but by the slot on the end of the bit. You simply line a modern SDS bit up with the drill’s chuck and insert it. If it doesn’t seat, turn the bit slightly (in either direction) until it does. The drill is ready for action. Rotary hammers have two or three settings. Two-setting rotary hammers can drill (in wood or steel) or drill with hammer action. Three-setting rotary hammers can drill, hammer drill, or move a chisel bit in a linear back-and-forth motion (obviously, never attempt to use a chisel in either hammer drill or drill mode and never use a drill bit in chisel mode). Setting a rotary hammer to drill in masonry is as easy as turning its dial to the double icon that has both a drill bit and a hammer.

The Famous Tapcon

All those are good for creating the hole, but then comes the fastening. It was in America’s bicentennial year, 1976, when Illinois Tool Works (ITW) patented what went on to become one of the most productive fastener systems ever invented, the Tapcon masonry screw and matching masonry drill bit. If you’re old enough to have fastened to concrete using a variety of the systems that preceded the Tapcon era, such as lead plugs and anchors that wedged themselves into the hole, you appreciate the beautiful simplicity of these things. Drill a hole, clean it out, drive the screw. But you don’t have to be an old timer (like me, ahem) to welcome the Tapcon.

The Tapcon (for Tapping Concrete) is a hardened steel screw. It’s intended to be used with a precisely sized matching masonry bit. The system is simple. Set a hammer drill to masonry-drilling mode and tighten the Tapcon bit in the chuck. Drill the hole and vacuum out the dust. Set the drill driver to screw-driving mode and drive the screw through the pilot hole in whatever you’re fastening to the concrete: lumber, a metal bracket, or some other fitting. The screw cuts its own threads into the concrete and the fastener tightens down beautifully against the surface of whatever you needed to fasten.

Best Practices

Drilling in masonry is simple, but there are some things you can get wrong. Here’s a list of tips to make sure you don’t.

Don’t use a standard drill.

Yes, you can make a hole in soft masonry materials like brick using a regular drill, but it’s slow and inefficient. Use a hammer drill set to, naturally, hammer drill mode.

Don’t force the bit.

Drilling in masonry is inherently slow, especially in concrete when you hit a lot of stone. Take your time and work your way through. Otherwise, you risk snapping the bit.

Be cautious drilling concrete.

Concrete has everything in it from reinforcing bars (rebar) to metal wire mesh to large pieces of stone. Sometimes, it even has embedded electrical conduit in it. The most common thing to hit is rebar. It will stop a masonry bit dead in its tracks. You’ve got two choices: Move the hole in a direction where you’re less likely to hit rebar, or buy or rent a specialized rebar-cutting masonry bit.

Clean out the hole.

Use a shop vacuum to remove dust and masonry chips before driving a Tapcon screw, using a wall anchor or embedding materials such as epoxy, grout, or mortar to hold a threaded stud. All masonry fastening systems (screws, anchors, and embedding materials) have a strength rating based on the assumption that the hole has been cleaned of debris. To reach the system’s design strength, clean the hole.

Use specialized bits for granite.

Don’t try drilling with your masonry bits in granite or marble countertops. That’s a fast route to getting some pretty nasty cracks in them. You’ll need a specialized bit instead.