Hole

A hole is a cylindrical cavity in a part, either through the material or to a specified depth, typically produced by drilling, boring or milling. It is one of the most common manufacturing features, and one of the first that feature-recognition systems learn to identify reliably.

What actually drives a hole's cost

A hole's cost depends on more than its diameter: depth-to-diameter ratio, required tolerance, thread or finish requirements, and whether it is through or blind all affect which operation and how much time it needs.

Where it appears on the drawing

As a diameter dimension, often with a depth callout for a blind hole, a thread callout if tapped, and sometimes a positional or perpendicularity tolerance.

Common mistakes

Assuming all holes of the same diameter cost the same; a deep, tightly toleranced or threaded hole can cost significantly more than a shallow, loosely toleranced one of the same size.

What's the difference between a through hole and a blind hole?

A through hole passes completely through the material; a blind hole stops at a specified depth without breaking through the other side.

Why does depth-to-diameter ratio matter for a hole?

Because a deep, narrow hole needs a longer tool prone to deflection and chip evacuation problems, which can slow the operation significantly.

Is a threaded hole just a hole with extra steps?

Effectively yes; it typically adds a tapping or thread-milling operation after the hole itself is drilled or bored.