Engineering Measurements
In engineering, measurements must be precise, repeatable, and within specified tolerances.
Tolerance
Tolerance is the acceptable range of variation. For example, a shaft specified as 25.00mm ±0.05mm must be between 24.95mm and 25.05mm.
Precision Instruments
- Vernier calipers — accuracy to 0.02mm
- Micrometers — accuracy to 0.01mm
- Dial indicators — for measuring deviations
- CMM (Coordinate Measuring Machine) — for 3D measurements
Common Engineering Conversions
| From | To | Factor |
|---|---|---|
| mm | inches | ÷ 25.4 |
| inches | mm | × 25.4 |
| microns | inches | ÷ 25,400 |
Best Practices
- Always specify units on drawings
- Use SI units (mm) for international projects
- Calibrate instruments regularly
- Record measurement conditions (temperature affects metal dimensions)