Formulas and Tables
(From the “Pocket Companion,” published by the Carnegie Steel Co.)
1. Weights
The average weight of wrought iron is 480 pounds per cubic foot. A bar 1 inch square and 3 feet long weighs, therefore, exactly 10 pounds. The weight of steel is 2 per cent greater than the weight of wrought iron, or 489.6 pounds. Cast iron weighs 450 pounds to the cubic foot.
2. Lengths
Circumference of circle = diameter × 3.1416.
Diameter of circle = circumference × 0.3183.
Side of square of equal periphery as circle = diameter × 0.7854.
Diameter of circle of equal periphery as square = side × 1.2732.
Side of an inscribed square = diameter of circle × 0.7071.
Length of arc = number of degrees × diameter × 0.008727.
3. Areas
Triangle = base × half altitude.
Parallelogram = base × altitude.
Trapezoid = half the sum of the parallel sides × altitude.
Trapezium, found by dividing into two triangles.
Circle = square of diameter × 0.7854; or,
= square of circumference × 0.07958.
Sector of circle = length of arc × half radius.
4. Standard Dimensions of Nuts and Bolts
Short diameter of rough nut = 11⁄2 × diameter of bolt + 1⁄8 inch.
Short diameter of finished nut = 11⁄2 × diameter of bolt + 1⁄16 inch.
Thickness of rough nut = diameter of bolt.
Thickness of finished nut = diameter of bolt − 1⁄16 inch.
Short diameter of rough head = 11⁄2 × diameter of bolt + 1⁄8 inch.
Short diameter of finished head = 11⁄2 × diameter of bolt + 1⁄16 inch.
Thickness of rough head = 1⁄2 short diameter of head.
Thickness of finished head = diameter of bolt − 1⁄16 inch.