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Gilson Binary Slide Rule

• Type: Circular
• Size: 8.25 in / 21 cm diameter
• Material: Enamel on aluminum
• Scales:
  • Front: D DI A K L LL3 LL2 LL1 LL0 binary-A binary-L drill/thread mm
  • Back: deg0-30 sin0-30 tan0-30 deg30-60 sin30-60 tan30-60 deg60-90 sin60-90 tan60-90

An older model, the enamel is trying valiantly to flake off. The Gilson Binary is a man's man's slide rule. In this case "binary" refers to the binary fractions that are commonly used in non-metric mensuration. Decimal conversions are supplied, and one can use the binary-L scale to add fractions together. A drill size scale aligns with the binary-L and mm scales for diameter conversions, and used with the thread scale ensures you won't drill a hole too small for your tap to thread. The binary-A scale runs from 0.1 to 10 in increments from 1/64 at the low end of the scale to 1/8 at the high end.