Drilling Into Concrete: Masonry Bits, Hammer Mode and SDS-Plus Explained

Steel is cut. Wood is cut. Concrete is crushed — a masonry bit does not slice material away, it hammers a blunt carbide wedge against the surface until the aggregate fractures, and the rotation exists mostly to present fresh rock to the wedge and screw the dust out of the hole. Understand that and the tool hierarchy stops being marketing: it is simply a ladder of how hard, and how usefully, the machine can hit.

Three tools, one ladder

The numbers land hardest as time: a 6 mm hole in cured C25 concrete is 30–60 seconds of full-bodyweight leaning with a percussion drill, and about 5–10 seconds of light guidance with an SDS-Plus. By the tenth anchor of the day that difference is not comfort, it is schedule.

The SDS shank is the detail that makes it work: the grooved shank slides axially in the chuck while carrying rotation, so the piston's blow travels straight down the bit into the rock instead of being soaked up by the chuck and your wrists. It also means an SDS bit in a three-jaw adaptor loses most of what you paid for.

The bit: a carbide wedge with a dust screw behind it

• The tip is a brazed tungsten-carbide insert. The classic is a single flat 2-cutter plate; better bits carry a 4-cutter cross head, which keeps cutting when it nicks rebar, drills a rounder hole, and splits the dust into four escape paths instead of two.
• The flutes are a conveyor, not a cutter — deep, polished flutes that clear dust are the difference between a bit that drills and one that seizes in deep holes.
• The steel body takes thousands of impacts; cheap bits fail at the braze or bend at the flute run-out long before the carbide wears.

From our range

Customizable SDS Max Drill Bit SDS Plus Drill Bit Set Flat/Cross Tip Carbide Masonry Drill Bit with Single/Double Flute

SDS-Plus and SDS-Max range, flat and cross-tip carbide — specified by shank and head type.

Doing the hole right

1. 01Mark the spot; with SDS just start — the machine will not wander the way a spinning twist bit does.
2. 02Hold the tool square and let it work. Do not wiggle to "help" — wiggling ovals the hole, and an oval hole is an anchor that pulls out.
3. 03Every 20–30 mm of depth, run the bit back out under power to clear dust. Packed dust is the main cause of stuck bits and cooked tips.
4. 04Blow or vacuum the finished hole. A dust-choked hole quietly costs a plastic plug much of its grip, and chemical anchors most of it.

Anchor holes: the pairing table

Drill depth = plug length + about 10 mm of spare for dust. The drill diameter matches the plug nominally — a 8 mm plug goes in an 8 mm hole; the interference you feel pushing it home is the design, not an error. In hollow brick, switch the hammer off once through the first skin, or the percussion breaks the webs the plug needs to grip.

Rebar: the full stop

A masonry bit meeting reinforcing bar announces itself — sudden refusal to advance, a change of note, sometimes a metallic squeal. Do not lean harder: hammering carbide against steel chips the insert and burns the braze. If the fixing position can move 30–40 mm, move it. If it cannot, this is what rebar-rated 4-cutter heads and dedicated rebar cutters exist for — slower, but they survive the encounter. Forcing a standard bit through rebar kills the bit and still leaves a bad hole.

Tile first, wall second

Drilling through tiled walls is a two-material job: glazed tile wants a non-hammer start with a tile bit (or a masonry bit at slow speed on a cross of masking tape to stop the skate), and only after the bit is through the tile does hammer mode come on for the wall behind. Percussion on the glaze is how tiles crack. The same spear-point tile bits handle glass and vitrified porcelain — the material logic is in the glass and tile drill range.

From our range

Multifunctional Drill Bit for Granite Marble Porcelain Ceramic Tile Construction

Spear-point tile and glass bit — the no-hammer starter for glazed surfaces.

What the trade actually buys

For anyone stocking masonry bits: consumption concentrates brutally on 6, 8 and 10 mm SDS-Plus in 110/160 mm lengths — the anchor sizes — with flat-tip bits as the price ladder and cross-tip as the premium step that wins the repeat order once a crew has felt the difference near rebar. Percussion-shank masonry bits still sell into the DIY and light-trade channel, and multi-material bits cover the fitter who meets tile, brick and block in the same afternoon. That is the split to mirror in a masonry and SDS order.