Choosing a Drill in Kenya: Impact, Hammer, and Why Your Bits Keep Breaking

A fundi is standing on a ladder trying to fix a bracket to a concrete lintel. The drill is screaming, the bit is glowing faintly at the tip, and after four minutes there is a shallow grey dimple in the concrete and nothing else. He leans harder. The bit skids, snatches, and snaps.

Nothing was wrong with his technique except two decisions made before he climbed the ladder: the drill was in rotation only mode, and the bit was a high speed steel bit meant for metal. Both are extremely common, and together they turn a ninety second job into a broken bit and a wasted afternoon.

Drills are the tool people buy first and understand last. The names overlap confusingly, the specification sheet emphasises the wrong numbers, and the accessory that actually determines success costs a fraction of the tool. This article sorts out which drill does what, how to read a specification that matters, and how to stop destroying bits.

Impact, Hammer, Rotary, Driver: Four Names, Three Tools

The vocabulary causes more bad purchases than anything else, so it is worth being precise.

An impact drill and a percussion drill are the same thing. The chuck rotates, and a mechanism behind it adds a rapid forward hammering action, thousands of small blows per minute. That combination of turning and tapping is what breaks up masonry so the bit can clear it. Switch the hammer action off and you have an ordinary drill for wood and metal. This dual nature is why it is the sensible first drill for most people.

A rotary hammer looks similar and is not. It uses a piston driving an air cushion to deliver far heavier blows, and it takes SDS bits that slot and lock rather than being gripped by a chuck. It is a specialist concrete tool. If you are drilling anchor holes in structural concrete all day, this is the tool that will still be alive next year.

An impact driver is a different animal again. It delivers rotational bursts rather than forward blows, which is what lets a small tool drive long screws without twisting your wrist. It is superb at fastening and poor at drilling masonry. Buying one expecting to make holes in concrete is a frequent and expensive mistake.

Reading a Specification, and Ignoring Most of It

Drill boxes shout about wattage. Wattage is the least useful number on the label, because it describes electricity consumed rather than work done. A poorly built 900 watt drill can be slower and shorter lived than a well built 700 watt one.

Four things genuinely matter.

Chuck capacity. Usually 10mm or 13mm. This sets the largest bit shank the tool will hold, and 13mm is the sensible choice because it accepts almost everything you will meet and tends to indicate a sturdier gearbox behind it.

Variable speed with a lock. Not a convenience. Speed control is the single most important factor in bit survival, for reasons covered below. A trigger that only has on and off will cost you money in broken accessories.

Reverse. Needed for backing a bit out of a bound hole and for removing screws. Its absence marks a tool built to a price.

A real side handle. When a large bit binds in concrete, the tool tries to spin instead of the bit. Without a second handle braced properly, that torque goes through your wrist. This is where drill injuries come from, and the handle in the box is not an accessory.

The Bit Decides the Outcome, Not the Drill

A capable drill with the wrong bit will fail at a job that a modest drill with the right bit finishes easily. There are three families and they are not interchangeable.

Masonry bits carry a blunt, wedge shaped tip of tungsten carbide brazed onto a steel body. They do not slice. They crush and chip the material while the flutes carry the dust out, which is exactly why they need the hammer action to work at all. Put one in steel and it will rub, polish and glaze the surface.

High speed steel bits have a sharpened cutting edge that shears metal away as a curl. They cut steel, aluminium and timber. Put one in concrete and the aggregate destroys the cutting edge almost immediately.

Wood bits have a small central point that pulls the bit into the timber and stops it wandering, with spurs that score a clean rim. They are for wood only.

Why Bits Break, and How to Stop It

Almost every destroyed bit comes down to heat, and heat comes from speed.

A cutting edge is hard because it was heat treated. Run it fast in a hard material and friction heats the tip past the temperature that treatment survives. The edge softens, stops cutting, and starts rubbing. Rubbing generates more heat, which softens more of the tip, and the bit is finished within a minute. The tell is a bit that has turned blue or straw coloured near the tip.

The rule runs opposite to intuition: the harder the material and the larger the hole, the slower the drill should turn. Slow rotation with firm steady pressure, so the edge is always taking a real cut rather than skating. If dust or swarf stops coming out, the bit has stopped cutting. Stop and find out why rather than pushing harder.

Three habits prevent most breakages. Drill a small pilot hole before any large hole in metal, because the dead centre of a big bit does not cut and simply pushes. Withdraw the bit periodically in deep holes to clear the flutes and let air in. And in metal, a drop of cutting oil roughly doubles bit life for a cost close to nothing.

Corded or Cordless in Kenyan Conditions

This is a genuine question here rather than a matter of preference, because it turns on power availability and on heat.

Corded tools give more sustained power per shilling, never run flat in the middle of a job, and have no battery to degrade. For bench work, a workshop, or anywhere with reliable mains, corded remains the better value.

Cordless earns its premium when the work moves. Roof work, fence lines, farm structures, sites without a connection yet, anywhere a cable is a trip hazard or simply will not reach. The cost is in the batteries, which are most of the tool's value and wear out first.

Two points specific to our climate. Lithium batteries dislike heat, so a pack left on a dashboard or in direct sun at midday ages considerably faster than one kept in shade. And where mains voltage sags, a corded motor labours and runs hot, which is a real argument for cordless on farms at the end of long spur lines.

Plenty of working fundis settle on both: a corded impact drill that handles masonry, and a cordless driver for assembly and fastening. That pairing covers more ground than either tool alone at any price.

Looking After It

Drills rarely die of overwork. They die of dust and neglect.

Masonry dust is abrasive and gets drawn straight through the motor by the cooling fan, where it wears the brushes and coats the windings. Blow the vents out regularly. Never block them with your hand while working, which is easy to do on a small tool and is a common cause of burnt out motors.

Keep the chuck clean and lightly oiled so the jaws close true. A chuck full of grit grips a bit off centre, and an off centre bit wobbles, cuts oversized holes and snaps. If the tool is corded, check the cable at the point where it enters the body, which is where flexing eventually breaks the conductors, and where a shock risk develops long before the tool stops working.

Let the tool cool if the body becomes uncomfortably warm. Continuous heavy drilling in concrete is the fastest route to a failed armature, and the tool gives you clear warning first.

What to Actually Buy

For a household or a farm that drills occasionally: a 13mm variable speed impact drill with reverse, a side handle, and a mixed bit set covering masonry, HSS and wood. That covers hanging gates, fixing brackets, assembling structures and light block work.

For a workshop doing metal fabrication: the same drill, plus a proper set of HSS bits in the sizes you actually use, plus cutting oil. Bit quality matters more than tool brand at this level of use.

For anyone drilling structural concrete regularly: stop trying to do it with an impact drill. A rotary hammer with SDS bits pays for itself in bits and in time within a few jobs, and it will not shake itself apart doing so.

We stock impact drills, metal and masonry drill bits, HSS sets, electric planers, circular saws, angle grinders and the rest of the workshop line across our branches. If you are unsure which class of tool your work actually needs, describe the job and we will tell you honestly, including when the cheaper tool is the right answer. Our full range is on the workshop and tools page, and current pricing is on the price list.

Frequently Asked Questions