When a customer stands in front of a wall of masonry drill bits, the first question is rarely about diameter. It is about the shank: will this bit fit my drill, and will it survive the job? Getting that one decision right separates a satisfied end user from a warranty claim, and it is the single most important thing a hardware buyer should understand before placing an order for masonry or electric hammer drill bits.
Why the Shank Decides Everything
Masonry drilling is a percussive process. Unlike a twist drill cutting metal, a masonry bit works by crushing and grinding: a tungsten carbide tip is struck thousands of times per minute while the body rotates, sweeping crushed powder out through the flutes. The tungsten carbide tip, rated around 9 on the Mohs hardness scale, is the only part of the tool hard enough to survive this repeated shock loading, and it is brazed or sintered onto a heat-treated steel body.
Because the material is fractured by impact, the way impact energy travels from the machine into the tip depends entirely on the shank system. There are two families in everyday use.
Round-Shank Masonry Bits
A standard masonry bit has a round (or hex) shank and a carbide tip brazed to a spiral steel body. It clamps in any conventional three-jaw chuck, which makes it the universal choice for hammer drills and ordinary cordless machines. Round-shank bits are the practical answer for holes up to roughly 12 mm in brick, mortar joints, sandlime brick and lightweight block, and for general fixing work where a dedicated rotary hammer is not available.
In a hammer drill, a pair of ridged clutch plates vibrates the bit forward as it rotates. That mechanism works well at low impact energies, but in dense structural concrete the shank is clamped rigidly, chuck wear accelerates and impact transmission becomes less efficient. This is why professional concrete work has moved to the SDS system.
SDS-Plus and SDS-Max
SDS stands for Slotted Drive System. Instead of a smooth shank clamped by jaws, the bit carries open slots and closed grooves that lock into a spring-loaded chuck while allowing 10 mm or more of axial float. The bit slides back and forth inside the chuck, so the rotary hammer's piston can strike the bit directly, delivering far more impact energy per blow than a hammer drill can through a clamped shank.
SDS-plus is the workshop standard for general concrete work: shank diameter 10 mm, two open grooves, suitable for bits from 4 mm to around 26 mm and machines rated up to about 4 joules of impact energy. SDS-max is the heavy-duty sibling, an 18 mm shank with three grooves for demolition-class rotary hammers and large-diameter bores from 12 mm upward.
The two systems are not interchangeable. An SDS bit will not clamp in a standard chuck, and a round-shank bit will not lock into an SDS chuck. A distributor who stocks both families, clearly merchandised, saves the customer the trip back to the counter.
Two-Edge or Four-Cutter?
Within the carbide tip itself there is a second tier of specification. The basic flat cross tip is a single carbide plate ground to a chisel edge: economical and fully adequate for soft brick, cinder block and low-strength concrete. A four-cutter (cross-ground) tip uses two carbide plates intersecting at 90 degrees to form an X-shaped head. The additional edges improve centering on entry, resist walking on smooth surfaces, and distribute wear across four contact points instead of two. In reinforced, high-aggregate concrete, four-cutter geometry typically outlasts a flat cross tip by 30 to 60 percent, and it clears dust noticeably better once hole depth passes 100 mm.
Practical Buying Guidance
Match the diameter to the anchor, never larger: a plug expands against the hole wall, and an oversize hole loses grip completely. Use hammer mode for all masonry work, since rotation alone glazes and destroys carbide tips. Pull the bit periodically to clear dust, and blow holes clean before inserting anchors, because packed dust reduces holding capacity. Finally, remember that a carbide masonry bit cannot cut rebar; reinforcement scanners are a sensible companion product for anyone drilling structural concrete.
FANXI manufactures the full masonry family: round-shank masonry bits in standard, high-helix and reduced-shank versions, long masonry bits for deep cavities, SDS electric hammer drill bits, carbide-tipped glass bits, solid carbide drills and steel chisels for masonry. Our OEM program covers private-label packaging and custom tip geometries for distributor ranges, with samples available on request.