Special Conversion Charts

Drill bits use three sizing systems: numbered (#80 to #1, smallest to largest), lettered (A to Z, increasing size), and fractional (1/16" to 1" and beyond). Numbered bits are used for small precision work, lettered bits fill gaps between fractional sizes, and fractional bits are the most common in general woodworking and metalworking. All three systems overlap in the mid-size range, and conversion charts help you choose the right bit regardless of which system your project specifies.

Wire gauge selection depends on three factors: amperage (current load), circuit length, and voltage drop tolerance. Use a wire gauge chart to match your expected amperage to the appropriate AWG size. For example, 14 AWG handles 15 amps, 12 AWG handles 20 amps, and 10 AWG handles 30 amps in typical residential applications. Always follow local electrical codes and consider professional consultation for critical installations. Thicker wire (lower AWG number) is required for longer runs to prevent voltage drop.

Lumber is sold by nominal size (e.g., 2x4), but actual dimensions are smaller due to drying and planing during manufacturing. A 2x4 actually measures approximately 1.5" × 3.5". This standard practice dates back to when lumber was cut to nominal size while green (wet), then allowed to shrink as it dried. Modern lumber is dried and surfaced before sale, resulting in smaller actual dimensions. A lumber size chart shows both nominal and actual dimensions for accurate project planning.

PSI (pounds per square inch) is the imperial unit for pressure, while Bar is a metric unit. The conversion is approximately: 1 Bar = 14.5 PSI, or 1 PSI = 0.069 Bar. PSI is commonly used in the United States for tire pressure, air compressors, and hydraulic systems. Bar is used internationally and in many technical specifications. Understanding both units is essential when working with imported equipment or following international specifications.

For most woodworking projects, rounding to 1/64" (0.015625") or 0.01" is sufficient. Fine furniture and precision joinery may require accuracy to 1/128" or 0.001". Power tools like table saws typically have adjustment precision around 1/64" to 1/32", so converting fractions to decimals within this range is adequate. For metal machining or engineering applications, much tighter tolerances (0.001" or less) are often required. Your conversion chart should match or exceed your tool's precision capability.

Absolutely! Laminating workshop charts is highly recommended for durability. Print on standard paper, laminate with 3-mil or 5-mil pouches for durability, trim edges carefully, and mount on your wall, toolbox, or workbench with magnets or adhesive. Laminated charts are resistant to oil, sawdust, dirt, and moisture, easy to clean with a damp cloth, and will last for years in harsh workshop environments. Consider printing multiple copies for different work areas.