Unit settings for mechanical drafting: when starting a mechanical drawing in AutoCAD, which unit type is generally appropriate for dimension entry and display?

Introduction / Context:
Mechanical drawings in many environments are dimensioned in decimal units (e.g., 2.375 inches or millimeters as decimals) to support machining precision and tolerance specification. Choosing the right unit format ensures clarity and compatibility with CNC/CAM.

Given Data / Assumptions:

• Typical mechanical shop practices prefer decimal inches or millimeters.
• Title blocks, dimension styles, and GD&T often assume decimal formats.
• Fractions are rare in precision machining contexts.

Concept / Approach:
Decimal unit settings enable fixed precision (e.g., 0.000) and easy tolerance display (e.g., ±0.005). While the base unit may be inches or millimeters, the numeric format is decimal, not fractional or architectural feet-inches.

Step-by-Step Solution:

Verification / Alternative check:
Compare plotted dimensions with the drafting standard; confirm correct decimal places and rounding.

Why Other Options Are Wrong:

• fractional: Common in carpentry, not precision machining.
• architectural: Uses feet-inches; suited to buildings, not parts.
• metric: Metric is a unit system, not a numeric format; in metric mechanical drafting you still use decimal format (mm).

Common Pitfalls:
Mismatching units between model and title block; always state and standardize units in the drawing notes.

Final Answer:
decimal