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Question

Difficulty: EasyScrews

When securing a thin piece of sheet metal to a frame where the back side is inaccessible for attaching a nut, which fastener is designed to cut or form its own mating threads directly into a pre-drilled hole?

  1. A
    Machine screw
  2. Sheet metal screwAnswer
  3. C
    Lag screw
  4. D
    Wood screw

Answer

Sheet metal screw
Sheet metal screws (often referred to as self-tapping screws) are engineered with fully threaded, hardened shanks and sharp cutting threads that create their own mating threads when driven into pre-drilled holes in sheet metal, making them ideal for blind joints.

Step-by-Step Solution

1
Analyze the workpiece material and assembly constraints
The workpiece is thin sheet metal with blind access (no access to the back side to secure a nut).
Understanding the material type and physical access dictates the required fastener thread profile.
2
Identify the fastener that creates its own internal threads in sheet material
A sheet metal (self-tapping) screw forms its own mating threads as it is driven.
Hardened sharp threads cut or displace thin metal to form a secure mechanical hold without requiring a pre-threaded hole or nut.

Key Concept

Sheet metal screw characteristics and self-tapping function in blind metal joints
Estimated Time:45s
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Topics

Screws

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