Threads and fasteners — Clarify the definition: Is an “internal thread” the thread formed on the inside (female) surface of a part such as a nut or a tapped hole, or is it located on the outside of a member?

Introduction / Context:
In mechanical design and technical drawing, threads are categorized as internal (female) or external (male). Confusing these terms can lead to incorrect specifications, mismatched components, and costly rework. This question checks your recall of the formal definition of an internal thread and reinforces the vocabulary used on engineering drawings and in shop practice.

Given Data / Assumptions:

• The statement claims an internal thread is on the outside of a member.
• We assume standard machine design terminology used across common thread systems (metric ISO, unified UNC/UNF, pipe threads, etc.).
• Objective: decide whether internal threads are inside or outside a part.

Concept / Approach:
An internal thread is formed on the inside surface of a hole and is intended to receive a matching external (male) thread, such as a bolt or screw. Typical examples include tapped holes in plates and the threads machined inside a hex nut. By contrast, an external thread is produced on the outside surface of a cylindrical feature (e.g., the shank of a bolt). Drawings label these with standardized callouts that specify thread series, pitch, class of fit, and other particulars.

Step-by-Step Solution:
1) Identify the term: “internal thread.”2) Recall the definition: internal = female = inside a part (nut, tapped hole).3) Compare with the statement: it incorrectly places an internal thread on the outside.4) Therefore, the statement is false.

Verification / Alternative check:
Consider a standard nut-and-bolt pair. The nut clearly contains the thread on its inside surface; this is the internal thread. The bolt carries the external thread on its outside surface. Thread gauges and inspection practices also distinguish “internal” gauges for holes versus “external” gauges for shafts.

Why Other Options Are Wrong:

• Correct: Incorrect because the statement is false.
• Context-dependent across standards: Naming conventions are consistent across major standards.
• Only true for tapered threads: Even tapered systems maintain the same inside/outside distinction.
• True for metric but not for unified threads: Both systems use the same terminology.

Common Pitfalls:
Mixing up “internal/external” with “right-hand/left-hand”; assuming surface location changes with thread class; overlooking that inserts (e.g., helicoils) still create internal threads in a hole.

Final Answer:
Incorrect