SDS-PLUS Round Shank Electric Hammer Drill Bits (28x350)

Concrete is not a uniform material. It is cement and sand around aggregate, and that aggregate is stone, sometimes very hard stone. A small bit meets one stone at a time and works its way past. A 28mm bit is wide enough to be sitting on several pieces of aggregate at once, and when it meets a particularly hard one the bit does not cut straight through it. It tends to skid off it, which pulls the bit slightly off line, and if you are pressing hard at that moment the bit can bind and the machine will kick.

So progress at this size is uneven by nature. The bit runs well, then slows, then runs again, and that is normal rather than a sign of a dull tool. The response that works is patience and a firm two handed grip with the side handle fitted, letting the hammer break the stone rather than trying to force the bit past it. The response that does not work is more pressure, which produces heat, wandering and a machine that twists in your hands.

It is also why a hole this size is worth starting carefully. Get the first twenty or thirty millimetres straight and square, and the hole will follow it. Start it at an angle and a long bit will keep going that way.

Twenty eight millimetre penetrations suit larger pipework, ducting and cable entries, and sleeved services through walls and slabs.

SDS-PLUS shank with hammer grade carbide and double narrow land flutes.

Buyers are mechanical and electrical services contractors, plumbers, air conditioning installers, civil trades and industrial maintenance.

Ask on 94 77 111 8880 and tell us the wall thickness, and we will confirm the length you need. We deliver island-wide.