Hammer drill

What it is

A hammer drill is a handheld power drill with a built‑in hammering mechanism that pulses forward and backward as the bit rotates. Those quick impacts chip brittle materials so the bit can cut and clear dust efficiently. Switch off the hammer function and you can use it like a standard drill for wood, metal, and plastic. This makes it a go‑to tool for drilling anchor holes in concrete, brick, and block.

How it works

Most homeowner hammer drills use a mechanical cam or clutch mechanism. As the chuck turns, toothed discs rub together and generate rapid impacts measured as blows per minute (BPM). The rotation plus percussion breaks up masonry while the flutes of a masonry bit carry dust out of the hole.

There is a related tool called a rotary hammer. It looks similar but uses a pneumatic piston to deliver fewer, much stronger blows. Rotary hammers accept SDS bits and excel at larger diameter holes, deeper holes, and light chiseling. For routine small anchor holes, a standard hammer drill is often lighter, cheaper, and easier to control.

Common DIY uses

• Installing Tapcon screws into concrete or brick
• Drilling holes for sleeve, wedge, or drop‑in anchors
• Hanging TV mounts, cabinets, gate hardware, or hose reels on masonry walls
• Setting masonry screw anchors for electrical boxes and conduit clips
• Drilling pilot holes in stucco or mortar joints for outdoor fixtures
• Boring through brick for cable pass‑throughs or wall plugs

Types and variations

• Corded hammer drills: Consistent power and often higher BPM. Good for longer sessions or tougher aggregate. You do not worry about battery runtime.
• Cordless hammer drills: Convenient and portable. Modern 18V/20V Max brushless models handle most household masonry tasks. Great for quick jobs and tight spaces.
• Drill/driver with hammer mode: Many compact drill/drivers include a hammer setting. Ideal if you want one tool that can drill, drive screws, and handle occasional masonry holes.
• Rotary hammer (SDS): A heavier category. Uses SDS‑Plus or SDS‑Max shanks and pneumatic impact. Best for larger holes (for example 1/2 inch and up), repeated anchors, or light chipping. Often has a chisel‑only mode, which ordinary hammer drills do not.
• Chuck types: Keyed or keyless 3/8 inch or 1/2 inch chucks for standard hammer drills; SDS chucks for rotary hammers.

Choosing the right hammer drill

Consider:
- Material and hole size: For 3/16–3/8 inch holes in brick or concrete block, a compact hammer drill is fine. For repeated 1/2 inch or deeper holes in cured concrete, a rotary hammer is quicker and less fatiguing.
- BPM and RPM: Higher BPM helps in masonry; check that the tool has a low‑speed gear for large bits. Typical hammer drills deliver 20,000–50,000 BPM.
- Torque and gearbox: Two‑speed gearboxes add control. Use low speed for masonry and large bits, high speed for small holes in wood or metal (with hammer off).
- Chuck size and grip: A 1/2 inch chuck holds larger shank bits and improves grip. A side handle improves control.
- Battery platform and motor: For cordless, match your existing battery system. Brushless motors run cooler and offer better runtime.
- Depth stop and clutch: A built‑in depth rod helps you stop at the right depth for anchors. A clutch protects screws and your wrist for non‑masonry tasks.

Bits and accessories

• Masonry bits: Use carbide‑tipped masonry bits marked for hammer drilling. Keep a small selection of 3/16, 1/4, 5/16, and 3/8 inch sizes for common anchors.
• SDS bits: For rotary hammers only; they lock into the SDS chuck. Do not use SDS bits in a standard hammer drill.
• Depth stops and tape: Set a depth rod or wrap tape on the bit to match anchor length.
• Dust control: A vacuum nozzle, dust shroud, or a partner with a shop vac improves speed and visibility and reduces silica dust.

How to use a hammer drill

1. Mark the hole location and confirm there is no hidden wiring or pipes. A stud and wire detector helps on finished walls.
2. Fit a carbide masonry bit of the correct diameter. Set the drill to hammer mode and low speed.
3. Use a side handle for control. Wear eye protection, hearing protection, and a dust mask or respirator.
4. Hold the tool square to the surface. Start the hole at low speed to prevent wandering.
5. Apply firm, steady pressure and let the hammering do the work. Every 1–2 cm, back the bit out to clear dust.
6. For deep holes, blow out dust with a hand blower or use a vacuum. Avoid compressed air indoors without dust capture.
7. Stop at the set depth. Test‑fit the anchor. If the hole is tight, ream briefly; do not force the anchor.

Maintenance and care

• Keep bits sharp and replace dull or chipped ones; sharp bits drill faster and run cooler.
• Clean dust from vents, chucks, and the depth stop after use. Store the tool dry.
• For rotary hammers, a light dab of SDS shank grease reduces wear. Check the manufacturer guide.
• For brushed motors, replace brushes as needed. For cordless tools, avoid full battery depletion and keep packs out of extreme heat.

Common mistakes to avoid

• Using hammer mode in wood or metal. Turn hammer off; it slows drilling and can damage material.
• Using the wrong bit. Wood or HSS metal bits will burn and dull immediately in masonry.
• Forcing the tool. Excessive pressure overheats bits and motor; let the percussion work.
• Skipping dust removal. Packed dust stalls progress and overheats bits. Clear the hole often.
• Drilling through tile with hammer on. Start with hammer off through tile or glaze, then engage hammer in the masonry behind it.
• Ignoring rebar. Hitting rebar can ruin a bit. If you strike steel, relocate the hole or use a rebar cutter with the proper tool.
• Underpowered setup. Small 12V hammer drills can struggle in cured concrete. Step up to 18V/20V or corded for dense material.

Related terms

• Rotary hammer: Heavier tool with pneumatic impact and SDS bits for larger holes and chiseling.
• Impact driver: Impacts rotationally for driving screws and lag bolts; not for drilling masonry.
• SDS, SDS‑Plus, SDS‑Max: Bit shank systems for rotary hammers.
• Tapcon: Brand name often used for concrete screws installed in predrilled holes.
• Anchor types: Sleeve, wedge, and drop‑in anchors used for securing loads to masonry.

Practical examples

• Mounting a TV bracket on a brick wall: Mark holes using the bracket as a template, drill 5/16 inch holes 2 1/2 inches deep with hammer mode, vacuum dust, insert sleeve anchors, and tighten bolts.
• Installing a hose reel on concrete block: Use mortar joints or block face, drill 3/16 inch pilot holes for concrete screws, brush out dust, and drive screws with hammer off using a drill/driver or impact driver.
• Setting a wedge anchor for a ledger: Drill the specified diameter hole to the correct depth with hammer mode, clear dust thoroughly, tap in the anchor, then tighten the nut to the torque spec to set the wedge.