SDS-PLUS Round Shank Electric Hammer Drill Bits (18x350)

SDS-Plus is the shank standard, and it is worth understanding what it is doing. Instead of being clamped by a chuck, the shank has grooves that slide inside the tool holder, so the bit is free to move back and forth a few millimetres while it turns. That is what lets a rotary hammer actually hammer — the piston strikes the end of the bit directly, and the energy goes into the masonry rather than into a chuck. It also means the bit drops in and locks with a push, with no key and no slipping.

The cutting head is premium-grade hammer carbide, specified for use with heavy-duty hammers. Carbide grade is what separates a bit that drills fifty holes from one that drills five: the tip has to survive being struck thousands of times per minute while abrading concrete, and a cheap grade either wears round or fractures when it meets rebar. At 18mm and above Harden uses a multi-cutter head rather than a single chisel tip, which puts more carbide edges in contact with the material. In practice that means it stays centred better on a big hole, cuts faster, and copes far better with the aggregate and reinforcement inside real structural concrete.

The flutes are a double narrow-land design, and flute design is what decides whether a deep hole works. Everything the tip cuts has to come back out along those flutes; if dust packs in, the bit stops cutting, heats up and starts to jam. On a 350mm bit going through a full wall thickness that is the difference between a clean hole and a seized bit. The double flute clears dust from both sides continuously.

This is a bit for concrete, block and masonry. It is not for tile, glass, timber or steel, and it is not a bit for a normal drill — it needs an SDS rotary hammer, and at 18mm it wants a decent one rather than the lightest machine on the shelf.

The buyers are electricians and air-conditioning installers running services through walls, plumbers coring for pipe, builders and steel fixers setting heavy anchors, and site contractors generally. Hardware shops supplying the building trade keep the common through-hole sizes in stock; these are packed 50 to a carton.

We carry the SDS-Plus range across the usual diameters and lengths, so if you need a set rather than a single size, message us on WhatsApp and we will price it and deliver island-wide.