How to Read a Metric Micrometer

Introduction

• Presenter: Bob Welds
• Topic: Using a Metric Micrometer for precise measurements
• Different types of micrometers:
  • Inside micrometers
  • Outside micrometers
  • Depth micrometers
  • Inch micrometers
• This session focuses on the metric micrometer
• Measures to the nearest 0.01 millimeters

Parts of a Micrometer

• Spindle: Moves
• Anvil: Fixed
• Knurls: Used to turn and adjust the micrometer

Reading the Barrel Scale

• Barrel Scale: Used for millimeter and half-millimeter measurements
• Thimble: Rotating part used to read measurements
• Observing the scale:
  • Marks above the line indicate millimeters
  • Marks below the line indicate half-millimeters

Examples

1. Example 1: Reads 12 millimeters
2. Example 2: Reads 14 millimeters
3. Example 3: Reads 11.5 millimeters (half mark showing)

Fine Measurements with the Thimble Scale

• The micrometer measures to 0.01 millimeters
• Thimble Scale: Contains 50 marks, each representing 0.01 millimeters
• Combining the barrel and thimble scale readings

Examples

1. Example 1: Barrel reads 12 mm, Thimble reads 0.33 mm → Total: 12.33 mm
2. Example 2: Barrel reads 11.5 mm, Thimble reads 0.22 mm → Total: 11.72 mm

Reading Partially Visible Marks

• Use the thimble scale to determine if a mark is starting or ending
• Trick: Look at the thimble numbers
  • If thimble numbers are large (close to 49), the mark is ending and shouldn’t be counted
  • If thimble numbers are small (close to 0), the mark is starting and should be counted

Conclusion

• Some micrometers have a vernier scale for more precise measurements
• Future lessons available on vernier scales if needed

Presenter Sign Off: Bob Welds, Weld Notes