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Question

Difficulty: HardDrilling and Boring Tools

A woodworker is preparing to mount concealed European-style hinges that require a 35 mm blind hole drilled precisely halfway into the thickness of a 3/4-inch solid oak cabinet door. Which of the following drilling tools is best suited to cut this clean, flat-bottomed hole without piercing the opposite face?

  1. A
    Spade bit
  2. Forstner bitAnswer
  3. C
    Auger bit
  4. D
    Standard twist drill bit

Answer

Forstner bit
The Forstner bit is uniquely designed to cut smooth, true, flat-bottomed blind holes. Because it is guided by its outer cylindrical rim rather than a long center spur or threaded lead screw, it requires only a tiny center point to register location, ensuring the bit does not pierce through thin stock while creating the flat floor needed for concealed hinge hardware.

Step-by-Step Solution

1
Analyze the technical requirements of the hole-making operation
The application requires a large-diameter (35 mm) blind hole with a flat bottom in shallow, solid hardwood without punching through the opposite face.
Concealed cup hinges require a flat seating area and precise depth clearance without damaging the front face of the door.
2
Evaluate bit cutting geometries against depth and profile constraints
Auger bits and spade bits rely on long center spurs or threaded lead screws that would penetrate through 3/4-inch stock; twist drills leave a 118° conical bottom.
Only a bit guided by its cylindrical rim with a tiny center locator can maintain a flat floor at a precise shallow depth.
3
Select the appropriate tool engineered for clean flat-bottom mortises
The Forstner bit is identified as the dedicated tool for boring smooth, flat-bottomed blind holes in cabinetry.
The shearing rim and lifter cutters of a Forstner bit produce a clean perimeter and a flat internal floor.

Key Concept

Tool Selection and Cutting Geometry for Flat-Bottomed Blind Holes
Estimated Time:1m 15s
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Topics

Drilling and Boring Tools

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