What Is an SDS Drill?

An SDS drill is a rotary hammer: a masonry drill with a piston-driven hammer mechanism built into the body. An electric motor spins a crank that drives a piston back and forth inside a cylinder. The piston compresses a cushion of air, and that air fires a striker into the back of the drill bit thousands of times a minute. The bit is hammered forward with real force while it turns, which is why an SDS drill goes through brick, block, stone and concrete with barely any pressure from you.

How is that different from a normal hammer drill?

An ordinary hammer drill (the hammer setting on a combi drill, for example) uses two ridged discs that rattle against each other. The hammer action is fast but feeble, and it only works when you lean hard on the tool. That is fine for the odd hole in soft brick, but in engineering brick or concrete the bit polishes the hole rather than cutting it, the motor strains and the job takes an age. A rotary hammer's pneumatic mechanism delivers a small number of far harder blows, measured in joules (J) of impact energy. Even a modest SDS drill with 1.5 J will outdrill the best combi in masonry, and it will do it all day without wearing out.

Why the SDS chuck matters

The hammer action only works because of the SDS bit system. SDS bits have slotted shanks that slide into the chuck and lock without a chuck key, yet stay free to move back and forth as the striker hits them. A conventional three-jaw chuck would grip the bit rigidly and shake itself loose. If you want the full story of the shank design and the name, read what does SDS mean?

The three SDS sizes

SDS-Plus is the everyday standard, taking bits up to about 26mm. Every major brand sells corded and cordless SDS-Plus drills, and most give you three modes: rotary drilling, hammer drilling and chiselling. SDS-Max is the heavy-duty system with a bigger shank and much higher impact energy, for large-diameter drilling and demolition; see our corded and cordless SDS-Max guides. SDS-Quick is a compact Bosch system for light 12v-class tools, covered in our SDS-Quick guide.

What jobs need an SDS drill?

Fixing to masonry is the obvious one: anchor holes for shelving, TV brackets, satellite dishes, gate hinges, fence post brackets and structural fixings. Beyond drilling, the rotation-stop mode on most models turns the tool into a light breaker for chasing cable runs into walls, lifting floor tiles, knocking off render and removing the odd brick. Plumbers and electricians drilling through walls for pipe and cable runs use them constantly, and with a core bit an SDS drill cuts the large holes needed for waste pipes and flues.

Choosing one

Match the impact energy to the work, decide between mains and battery power, and check the weight suits the job; our full guide to buying an SDS drill walks through every decision. Or browse all 116 drills we cover on the search page.