Makita B-66656 Review

Running pipes, ducting, and large-diameter cables through concrete walls, floors, and foundations is a job that separates standard drill bits from serious tooling. A standard SDS-Plus twist drill might manage up to 30 mm, but when you need a 60 mm hole for a waste pipe or an extractor duct, you move into core drill territory. Core bits for rotary hammers use a cylindrical cutting head studded with carbide or diamond segments that cut a ring around the perimeter of the hole, removing a solid core rather than grinding the entire diameter into dust. This approach is faster, uses less energy, and produces a cleaner hole with less risk of spalling the exit side. For plumbers coring through walls for soil pipes, electricians running large conduit, and builders installing ventilation, a quality core bit matched to a powerful rotary hammer turns what would be an hour of chiselling and patching into a clean, two-minute operation.

Large-diameter core bits for rotary hammers are specialist accessories designed for tradespeople who regularly need holes beyond the capacity of standard twist drills. They come in several types: carbide-tipped for brick, block, and soft concrete; diamond-segmented for reinforced concrete and hard aggregate; and bi-metal for mixed materials. The key compatibility factors are the shank type — SDS-Plus, SDS-Max, or spline drive — and the maximum diameter the host rotary hammer can drive effectively. A 64 mm core bit demands a rotary hammer with sufficient impact energy and torque to prevent stalling, and it is typically used with rotation-stop disengaged so the tool is hammer-drilling rather than pure rotary cutting. Makita's B-66656 is a 64 mm diameter rotary hammer cutter designed for large-diameter hole drilling in masonry, built to Makita's professional standards for durability and cutting speed.

This review examines the Makita B-66656 64 mm rotary hammer cutter in detail — its construction and cutting design, the rotary hammer requirements for driving it effectively, the materials and applications it handles, and how it fits into a professional toolkit alongside smaller drill bits and dedicated core drilling rigs.

The Makita B-66656 is a 64 mm diameter rotary hammer cutter — also referred to as a core bit or hole saw for masonry — designed for use with compatible rotary hammers. At this diameter, the bit removes a circular plug of material by cutting a ring rather than pulverising the entire hole volume, which is significantly more efficient in terms of both time and energy consumption. The 64 mm diameter accommodates common plumbing and HVAC requirements: 50 mm waste pipes with clearance, 60 mm ducting, and large-gauge electrical conduit. Makita's professional tooling standards mean the cutter is manufactured to tight tolerances for concentricity — an out-of-round core bit creates oversized, ragged holes and puts uneven load on the rotary hammer's bearings.

The cutting head uses carbide-tipped segments arranged around the perimeter of the cylindrical body. Carbide provides good wear resistance in brick, block, and standard concrete, though it will dull more quickly in heavily reinforced concrete where the segments encounter steel rebar. The cutter body is designed to clear debris efficiently through flutes or slots that channel dust and chips out of the cut, preventing the bit from binding as it progresses deeper into the material. At 64 mm diameter, chip clearance is particularly important because the volume of material being removed per millimetre of depth is substantial.

Driving a 64 mm core bit requires a rotary hammer with sufficient impact energy and motor torque. This is not an accessory for a compact 18-volt cordless SDS-Plus drill — it needs a corded SDS-Max or high-power SDS-Plus rotary hammer delivering at least 5 to 8 joules of impact energy to maintain cutting speed without stalling. The rotary hammer should be set to hammer-drilling mode (rotation with impact), as the impact action is what fractures the material ahead of the carbide tips. Attempting to use rotation-only mode in masonry will rapidly overheat and dull the cutter. The bit should be withdrawn periodically during deep cuts to clear debris from the kerf and allow the cutting edges to cool.

Makita design and manufacture their own tooling to match their rotary hammers, so the B-66656 is optimised for use with Makita's professional SDS-Max and high-power SDS-Plus machines. It can be used with other brands' rotary hammers provided the shank type and size are compatible, though optimal performance comes from the matched Makita system where the tool's impact characteristics are tuned to the cutter's design. The cutter is supplied as a single unit weighing approximately 45 grams at the business end — a surprisingly low weight that reflects the efficient hollow-body design rather than a solid mass of steel.

At around £187, the B-66656 is priced as a professional-grade tooling item — significantly more than generic core bits but in line with Makita's positioning as a premium manufacturer. It holds no customer reviews on Amazon, which is typical for specialist trade tooling bought through merchant accounts rather than consumer retail. For plumbers, electricians, and builders who regularly core holes in masonry and need a reliable 64 mm cutter that will survive repeated use on site without the teeth stripping or the body warping, the Makita B-66656 represents a professional investment in a consumable that — when used correctly with an adequately powered rotary hammer — should deliver clean, accurate holes through hundreds of installations before needing replacement.

This 64 mm Makita rotary hammer core bit is designed for professional plumbers, electricians, and builders who need to drill large-diameter holes through masonry walls, floors, and foundations for pipes, ducting, and conduit, using a compatible high-power SDS-Max or SDS-Plus rotary hammer.