How to Use a Rotary Hammer Safely and Effectively

What a rotary hammer does differently

A rotary hammer is built to drill into concrete, stone and brick. Instead of a light ratcheting action, it uses an internal piston that delivers a strong, direct blow to the back of the bit while the bit also turns. The result is that the bit chips away material with each strike and the rotation clears the dust out of the hole.

This is different from an ordinary hammer drill, which uses a lighter, ratcheting action that is fine for small holes in brick or block but slow in hard concrete. If you are weighing the two, the hammer drill selection discussion covers that choice. Here, the focus is how to use a rotary hammer once you have one.

Understanding the modes

Most rotary hammers have a mode selector, often a dial or a switch with symbols. Names and symbols vary, so check the manual for yours. The common settings are:

• Hammer drilling (rotation plus hammering). The main mode for drilling holes in masonry. The bit turns and strikes at the same time.
• Drill only (rotation without hammering). For drilling wood or metal with a suitable bit, or for driving fasteners with the right adapter. Rotary hammers are not designed to be general-purpose drills, so this mode is occasional use.
• Hammer only (hammering without rotation). Used with chisel and scaling attachments for chipping concrete, removing tile or breaking small sections. Many tools also have a chisel-positioning setting that lets you lock the chisel at a chosen angle.

Change modes only as the manual describes. On many tools the selector should be moved only when the tool has stopped, and some designs need the chisel position to be locked before you start.

Choosing masonry bits

Bits for hammer drilling look different from standard twist bits. Two broad families are common:

• SDS-type bits. These have a special shank with grooves that let the bit slide back and forth in the holder, so the hammering action reaches the bit effectively. SDS bits fit tools with a matching holder. Several versions exist, with different sizes, so confirm that your bit and your tool match.
• Carbide-tipped round-shank masonry bits. These are found in chucks on lighter hammer drills. They work for smaller holes in brick or block but are not suited to the heavy blows of a rotary hammer.

For hammering only, use chisels, points and similar attachments made for your tool’s holder. Do not use a standard steel drill bit as a chisel.

A few general points about bits:

1. A dull or damaged bit slows the job and can strain the tool. Replace worn bits.
2. Wipe off or inspect the shank, and apply a light amount of grease if the manual recommends it.
3. Keep bits straight and avoid bending them under load.
4. Match the bit diameter and length to the anchor or fastener you are installing. The wall anchors for masonry you choose will specify a hole size, so follow that rather than guessing.

A basic drilling procedure

1. Check the area. Concrete may contain reinforcing steel, conduit or pipes. If you are unsure what is behind a surface, try to find out first. Hitting a live electrical line is a serious hazard, so turn off power to the circuit if there is any doubt, and follow local rules.
2. Mark the hole. Use a pencil or marker to show the location.
3. Put on your protection (see below).
4. Seat the bit by pushing it into the holder until it locks. Pull on it lightly to confirm it holds.
5. Set the mode to hammer drilling.
6. Hold the tool firmly with both hands, using the side handle. Brace your stance so a sudden bind will not throw you off balance.
7. Start at a lower speed to avoid the bit skating off the mark, then increase as it seats.
8. Let the tool work. Apply steady, moderate pressure along the axis of the bit. Leaning heavily rarely speeds things up and can overheat the bit.
9. Withdraw the bit from time to time on deeper holes to clear dust.
10. Clean the hole with a brush or air as the anchor instructions say, because dust left in the hole can reduce an anchor’s grip.

If the bit snags on rebar, release the trigger promptly. Many rotary hammers have a clutch that slips under sudden binding, but do not count on it to protect your wrists. Maintain a stance that lets you let go of the tool.

Protecting your hearing, eyes and lungs

Hammering into concrete is loud and dusty, and both hazards deserve real attention.

Hearing. Rotary hammers are among the louder tools in a typical kit. Wear hearing protection rated for the noise level, such as earmuffs or earplugs, every time you use one, and not only for long jobs. Hearing and dust protection are worth putting on before you pull the trigger.

Eyes. Concrete chips and fragments can fly out of the hole. Wear safety glasses or goggles that meet recognized impact standards. When chiseling, goggles that seal around the eyes offer better coverage.

Lungs. Dust from concrete, brick and stone can contain fine silica particles, which are harmful when inhaled over time. Use dust control: a dust-extraction attachment connected to a suitable vacuum, if your tool supports one, and a properly fitted respirator made for fine particles. A basic paper dust mask is generally not adequate for silica. Wet methods and good ventilation also help. For regular work, check the safety rules that apply in your area.

Hands and body. Vibration travels into your hands and arms. Take breaks, keep your grip firm but not clenched, and use anti-vibration handles if the tool has them. Wear gloves that give a secure hold without being loose.

Battery and corded considerations

Battery rotary hammers are available and handy for overhead or remote work, but concrete drilling pulls a lot of energy from the pack, so expect shorter run time on large holes. Corded models are common for steady, repetitive drilling. Whichever you use, remove the battery or unplug before changing bits or making adjustments.

Common mistakes

• Using the wrong bit type for the tool’s holder.
• Pressing hard instead of letting the hammering do the work.
• Forgetting protection because a job seemed short.
• Drilling without checking for hidden steel or utilities.
• Using hammer mode on tile or soft material that can crack under impact.

Used with care, a rotary hammer makes light work of masonry. The safe approach is simple: choose the right mode and bit, hold the tool securely, and protect your ears, eyes and lungs every time.