SDS drill: common mistakes and how to avoid them

Learn to fit bits, choose the right mode, and drill safely with an SDS drill without common beginner mistakes.

SD-01Understand what makes an SDS drill differentSDS stands for a special chuck system that lets the bit move slightly in and out while spinning, so the drill can hammer as well as rotate. This makes it far better than an ordinary drill for masonry, brick and concrete. The beginner mistake is treating it like a normal drill and expecting a wood or metal bit to fit - SDS bits have a grooved shank and only work in an SDS chuck.

SD-02Fit the drill bit properlyPull back the collar (the ring) at the front of the chuck, push the SDS bit's grooved end straight in until it clicks, then let the collar go. Give the bit a gentle tug to check it's locked in - it should not pull out but should still spin and slide slightly in your hand. The common mistake is not pushing the bit in far enough, so it looks fitted but drops out mid-drill.

SD-03Choose the correct mode before you switch onMost SDS drills have a dial with symbols: a drill bit alone means rotation only (for wood or metal with the right bit), a drill bit with a hammer means rotation plus hammer action (for brick, block and concrete), and a hammer alone means chisel mode with no rotation (for chipping tile or plaster). Check the dial every single time - the classic mistake is leaving it on hammer mode from the last job and destroying a screw hole or splitting tile.

SD-04Get your stance and grip rightHold the side handle with one hand and the main body with the other, stand with feet apart and your weight slightly forward, and keep the drill as square to the wall as possible. Don't lock your arms rigid - let your body absorb some of the vibration or your wrists will ache fast. Beginners often grip too tightly and fight the tool instead of guiding it.

SD-05Check what's behind the surface before you drillBefore drilling into any wall, floor or ceiling, use a cable and pipe detector to scan the area, but treat this as a first check, not a guarantee. Detectors can miss cables that run deep, sit in metal conduit, hide behind metal-backed plasterboard, or simply don't follow the usual safe zones - and older or amateur wiring often ignores those zones completely. If there's any doubt at all, isolate the circuit at the consumer unit before drilling near where cables might run, and turn off the water at the stopcock before cutting into anything that could carry water. Always expect something to be there and prove otherwise, rather than assuming a clear scan means it's safe.

SD-06Let the drill do the work, don't force itStart the hole at a low speed with light pressure until the bit bites, then increase speed and apply steady, moderate pressure - the hammer action does the breaking up, your job is just to keep the bit in line. The most common mistake is leaning on the drill hard, which overheats the bit, wears it out fast and makes the hole wander off angle. Pull the bit out every few seconds to clear dust, especially in deep holes, or it will clog and slow you down.

SD-07Check you've drilled it rightA good hole is straight, round, and the right depth for what you're fixing - use the depth stop rod (a metal bar through the side handle) or mark the bit with tape to judge depth consistently. Push a wall plug in by hand; it should go in snugly with slight resistance, not fall in loosely or need hammering. If dust keeps coming out grey and fine rather than gritty, or the hole feels wider at the front than the back, you've likely wobbled the drill off-angle partway through.

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