Diameters of Number Drills
Complete Reference Chart: #1 to #80 in Inches and Millimeters
This comprehensive chart provides the precise diameters of number drills from #1 through #80, showing measurements in both inches and millimeters. Number drills are essential for accurate drilling operations, particularly for tapping holes and precision machining work.
Chart Features:
- • Complete listing of number drills from #1 to #80
- • Precise measurements in inches (decimal format)
- • Metric equivalents in millimeters
- • Easy-to-read tabular format for quick reference
- • Essential for selecting correct drill sizes for tapping operations
- • Useful for precision machining and manufacturing
Understanding Number Drills
Number drills are a standardized drill bit sizing system commonly used in the United States. The numbering system runs from #1 (largest) to #80 (smallest), with each number representing a specific diameter. This system provides precise sizing options between fractional inch sizes.
Number drills are particularly important when selecting the correct drill size for tapping threads, where precision is critical for achieving proper thread engagement and strength.