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What is an SDS drill and when do you need one?

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In short

An SDS drill, or rotary hammer, uses a piston to deliver strong hammer blows, measured in joules, through a special slotted bit that slides in the chuck. It drills concrete and hard masonry far faster than a combi drill, and most can chisel. You need one if you drill concrete often, need holes above about 10 mm or plan renovation work.

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SDS drills are the tools that make short work of concrete lintels, block walls and old tiled floors. They look like a bulky drill with a side handle, and they use their own bits. This article explains what SDS means, how the hammer works, the difference between SDS plus and SDS max, and when it is worth buying one.

What SDS means

SDS describes the bit holding system, from the German Steck, Dreh, Sitz, roughly insert, twist, stays. The bit has grooves along its shank. Two open grooves let it slide into the chuck and lock, and closed grooves keep it from falling out while letting it move back and forth. That movement lets the hammer blows reach the bit tip rather than being absorbed by chuck jaws.

Bits push in and click, with no key or tightening, and come out with a pull of the chuck sleeve.

  • RoundFits: keyless chuck
  • Hex 6.35 mmFits: impact driver
  • SDS plusFits: SDS plus drill
  • SDS maxFits: SDS max breaker
Shank ends and the tools that take them.

SDS plus and SDS max

SDS plus bits have a 10 mm shank and are used in most cordless and light corded SDS drills, for holes from about 4 to 28 mm and light chiselling. SDS max bits have an 18 mm shank and go in heavier rotary hammers and breakers for large holes, cores and demolition.

For home and most trade fixing work, SDS plus is the right size.

SDS plusSDS max
Shank10 mm18 mm
Typical toolsCordless and light corded drillsHeavy rotary hammers, breakers
Typical holes4 to 28 mmLarger holes and cores
ChisellingLight, tiles and renderHeavy demolition
SDS sizes

How the rotary hammer works

Instead of ridged discs, an SDS drill uses a crank driven piston to compress air that throws a striker against the back of the bit. The blow energy is much higher than a combi drill's, and the tool does the work, so you need only light pressure. Makers quote the energy in joules: cordless SDS plus drills commonly sit between about 1 and 3 J.

Most SDS drills have three modes: rotary only for wood and metal with an adaptor chuck, rotary hammer for masonry, and hammer only (chisel) for removing tiles, plaster and render.

impacts turn the bit
hammer pushes into masonry
An impact driver's blows turn the bit; a combi drill's hammer pushes it forward.

When a combi drill struggles

A combi drill is fine for the odd plug hole in brick. It struggles with dense concrete, engineering brick, larger anchor holes for gates and frames, core holes and long runs of fixings. Bits overheat and wear, and your wrists take the strain.

An SDS drill handles those jobs easily. Compare the two in SDS drill vs combi drill.

Choosing a cordless SDS drill

Check impact energy in joules, maximum hole size in concrete, the number of modes and the weight. Safety features such as kickback control are worth having. Many SDS drills are sold bare, so check whether batteries and a charger are included.

Our cordless SDS drill guide compares current models and box contents.

  • Light fixing holes overhead: 12 V or compact 18 V around 1 to 1.5 J.
  • General renovation: 18 V around 2 to 3 J with chisel mode.
  • Heavy anchors and coring: twin 18 V or larger corded tools.

Bits and accessories

SDS plus bits come in lengths from about 110 mm to over 400 mm, so check you can drill through a full wall when you need to. Four cutter heads drill cleaner, rounder holes in reinforced concrete than two cutter heads. Chisels come as points for breaking, flat chisels for chasing and wide tile chisels for lifting floor tiles.

An adaptor chuck with an SDS shank lets you fit round shank wood and metal bits, though some drills have quick change chucks instead. Dust extraction attachments are available for many cordless models and are well worth having indoors.

Using one safely

Hold the drill with both hands using the side handle. Let the tool work rather than leaning on it. If the bit jams on rebar, an SDS drill can twist hard, so kickback control and a firm stance matter. Use a depth stop for consistent hole depth.

Drilling and chiselling masonry creates silica dust and noise. Use extraction where possible and wear eye, ear and dust protection.

Note:Scan walls and floors for cables and pipes before drilling. Wear eye, ear and dust protection, and follow the manual and HSE guidance on dust, noise and vibration.

Frequently asked questions

Can an SDS drill be used for wood? Yes, in rotary only mode with an SDS wood bit or an adaptor chuck for round shank bits. Some models have a quick change chuck.

Do I need an SDS drill for a few shelves? No. A combi drill handles plug holes in brick and block. An SDS drill is worth it for concrete and frequent work.

Can SDS drills drive screws? Not well. Most have no clutch. Use a drill or impact driver.

Is SDS max too much for home use? Usually yes. SDS max tools are heavy and aimed at large holes and demolition.

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