Examkin

Question

Difficulty: MediumDrilling and Boring Tools

A technician fabricating an aluminum instrument bracket needs to create a clean, deburred 1/2-inch hole through 18-gauge sheet metal without distorting the workpiece or having the cutting edges snag upon breakthrough. Which drilling tool is specifically designed with graduated, tiered cutting diameters along a single conical body to perform this task?

  1. A
    Brad-point bit
  2. Step drill bitAnswer
  3. C
    Spade bit
  4. D
    Auger bit

Answer

The step drill bit is the correct tool for boring clean, controlled holes in thin sheet metal without binding.
The step drill bit features a conical profile with progressively larger cutting steps along its length. This stepped architecture allows each tier to act as a pilot for the next diameter, preventing the cutting edge from grabbing or tearing thin metal panels and automatically deburring the hole edges.

Step-by-Step Solution

1
Analyze the material thickness and cutting characteristics of the workpiece
Identified 18-gauge sheet metal, which is thin and prone to grabbing, chatter, and distortion when cut with standard flutes.
Thin materials lack the axial depth needed to guide conventional drill margins, often resulting in tearing when cutting lips break through the underside.
2
Evaluate the geometric design of hole-making tools across the options
The step drill bit features a tapered series of distinct cylindrical steps that increase progressively in diameter.
Each step cuts a shallow radial ledge and deburrs the previous step, eliminating breakthrough binding and creating smooth, round holes in sheet materials.

Key Concept

Application and geometry of step drill bits for thin-gauge metal fabrication
Estimated Time:1m 0s
Rate this question

Topics

Drilling and Boring Tools

More questions from this topic