Forstner Drill Bits

Forstner Drill Bits

Forstner drill bits produce flat-bottomed, clean-sided holes in wood — a hole type that standard twist drills and spade bits cannot produce accurately. The circular rim of the Forstner bit scores a clean periphery, and the central spur anchors the bit accurately on the marked centre before any material is removed by the rim. The result is a precisely located, flat-bottomed hole with minimal tear-out at the surface. Forstner bits are the correct tool for hinge boring, shelf pin drilling, concealed fitting pockets, and any application in joinery and cabinetry where hole quality and accuracy matter. AIMS Industrial supplies Forstner bits for woodworking, joinery, and cabinet making applications.

Construction and Geometry

The Forstner bit has three key elements: a centre spur that pilots the bit into the material; a pair of angled outer cutters (chippers) that remove the bulk of the material from the bottom of the hole; and a continuous rim (or a serrated saw-tooth rim in the self-cleaning variant) that scores the clean periphery. The standard round-rim Forstner bit works best on the drill press where a controlled, steady feed rate is applied. Sawtooth (also called multi-spur or serrated) Forstner bits are more aggressive, clear chips better in deep holes, and can be used in handheld drills more successfully than the standard form.

Applications

Forstner bits are used in:

• Hinge boring (35mm diameter is the standard for concealed cup hinges in cabinetry)
• Shelf support pin holes in cabinet sides
• Lock body pockets in doors
• Any application requiring a clean, flat-bottomed hole — including cross-grain holes, angled holes, and overlapping or tangential holes that would cause twist drills to wander

Drill Press vs Handheld Use

Forstner bits require a rigid, consistent feed rate and speed — a drill press is the correct tool for most Forstner bit work. High-quality sawtooth Forstner bits can be used in a handheld drill at low speed for hinge boring where a press is impractical. Always use a backing board to prevent tear-out at the exit of through-holes. For bit selection for specific timber and joinery applications, contact our team.

Size Range and Sets

Forstner bits are available individually in specific diameters and in multi-piece sets covering the most common sizes. Sets typically range from 15mm to 50mm in 5mm steps, providing the key diameters for hinge boring, shelf pins, and lock pockets in one kit. The 35mm diameter is the specific size required for standard concealed cup hinges — the most common Forstner bit application in cabinet and furniture making. AIMS Industrial stocks Forstner bits for woodworking and cabinet making applications across Australia.