Forstner drill bit: drilling diameter: 21 mm / 0.83 \"; shank size: 7 mm / 0.28 \"; drilling depth: 48mm / 1.89 \"; total length: 77mm / 3.03 \". Tungsten carbide cutter and solid hardened steel body, round shank Forstner drill bits for woodworking. Applications: Can be used for drilling holes in wood and plastic products, furniture, door hinges. Used for cutting wood, plywood, solid wood boards, MDF, plastic, fiberglass, etc. The Forstner drill bit is intended for general use. Features: Tungsten carbide cutting tip with special heat treatment for sharp cutting edge, high hardness, no burrs and durable use. . Head with arc-shaped design for easy chip removal, more efficient punching. How to use: suitable for pillar drilling machine, vertical drilling machine, CNC cutting machine. Processing of hardwood or other hard materials should be injected with water to improve drilling quality and precision and extend the life of the hole saw blade. Advice: Max speed: 2000 rpm. Used on office equipment (stationary) and MUST NOT be used on handheld power tools (e.g. hand drill or electric drill). Cannot drill into metal and non-ferrous metals. To avoid damage, make sure there are no nails or other metal objects in the wood before drilling. The opener's cutting edge and tip should be sharpened in time.