Which Demolition Hammer: 5 kg, 11 kg or 16 kg?

Almost nobody walks in asking for a GSH 11 VC. They ask for the gyaarah kilo wala, or for “the one that will break a slab”. That is the right way to think about it, and it is how Bosch file these machines themselves — the catalogue pages are headed DEMOLITION BREAKER <11 KG, >14 KG, >16 KG.

Why weight is the specification that matters

A breaker works by lifting a piston and dropping it on the back of the chisel. The energy in that blow is what the catalogue calls impact energy, measured in joules, and it scales almost directly with how much machine there is to absorb the recoil. A five-kilo machine delivers around seven and a half joules. A thirty-kilo machine delivers sixty-two. That is not a small difference in degree; it is the difference between chipping a surface and removing a floor.

Weight cuts the other way too, and this is the part people underestimate. Everything above about fifteen kilos is a machine you stand over and push down, not one you hold up. A sixteen-kilo breaker cannot be used on a wall at chest height for any length of time, no matter how much energy it has. If the work is overhead or vertical, the lighter machine is not the compromise — it is the correct tool.

Which weight for which job

Five kilos — GSH 5, GSH 5 HX, GSH 500

Tile and plaster removal, chasing walls for conduit, breaking brick partitions, lifting floor tiles, trimming openings. Light enough to use horizontally and above shoulder height, which is most of what an electrician or a tiling contractor needs. It will break a thin concrete slab, slowly. It is the wrong machine for a day of floor demolition.

Ten to eleven kilos — GSH 11 E, GSH 11 VC

The middle of the range and the one most general contractors end up owning. At sixteen to twenty-three joules it goes through reinforced slabs, beams and column corrections, and it is still liftable for short vertical work. The VC in GSH 11 VC is Vibration Control, which matters more than it sounds: on a machine this size, vibration is what ends the working day, not power.

Fourteen kilos and up — GSH 14 C, GSH 16-30, GSH 27 VC

Floors, foundations, road surfaces, mass concrete. These are two-handed, downward machines; the GSH 16-30 ships with a trolley because moving it around a site is itself part of the job. Buy at this weight when the work is measured in square metres of floor, not in metres of wall.

The chisel fitting is not a detail

This is the mistake that costs real money. The shank that fits into the machine comes in several patterns and they do not interchange. SDS-max on the lighter machines; 22 mm, 28 mm and 30 mm hexagon on the heavy ones. A yard full of 30 mm hex points is worth nothing to a new SDS-max breaker, and a set of chisels for a heavy breaker is not a trivial purchase.

• Already own chisels? Start from the shank you have and work back to the machines that take it, not the other way round.
• Buying the first one? SDS-max is the more common fitting across the lighter machines, so chisels are easier to replace locally.
• Hiring out the machine? Match whatever your crews already carry. A site with two shank patterns loses a chisel set eventually.

Breaker or rotary hammer?

A breaker only hammers. It has no rotation, so it cannot drill a hole — every joule goes into the chisel. A rotary hammer drills and, on most models, also chisels. If you need both, and the demolition is occasional, a heavy rotary hammer does both jobs adequately. If the demolition is the job, a breaker does it faster and will outlast a rotary hammer being used for work it was not designed around.

What people get wrong

• Buying on power in watts. Watts describe the motor, not the blow. The GSH 14 C and the GSH 16-30 draw the same 1,750 W and deliver 28 J and 41 J. Read the joules.
• Buying the heaviest affordable machine. If the work is vertical or overhead, extra weight is weight you hold up. Half the people who regret a sixteen-kilo breaker bought it for wall work.
• Ignoring the chisel fitting. It is the one spec that makes a cheap machine expensive.
• Running without grease. Every one of these ships with a grease tube for a reason. A dry hammer mechanism is the most common reason a breaker comes back for repair.

See the breaking and drilling range or tell us the job — the wall, the floor, how much of it — and we will say which weight it needs. Prices include GST, with a proper tax invoice on every order.