USEFUL INFORMATION FOR THE WORKSHOP
To find the circumference of a circle: Multiply the diameter by 3.1416.
To find the diameter of a circle: Multiply the circle by .31831.
To find the area of a circle: Multiply the square of the diameter by
.7854.
To find the area of a triangle: Multiply the base by one-half the
perpendicular height.
To find the surface of a ball: Multiply the square of the diameter by
3.1416.
To find the solidity of a sphere: Multiply the cube of the diameter by
.5236.
To find the cubic contents of a cone: Multiply the area of the base by
one-third the altitude.
Doubling the diameter of a pipe increases its capacity four times.
To find the pressure in pounds per square inch of a column of water:
Multiply the height of the column in feet by .434.
Standard Horse-power: The evaporation of 30 pounds of water per hour
from a feed water temperature of 1,000 degrees Fahrenheit into steam at
70 pounds gauge pressure.
To find the capacity of any tank in gallons: Square the diameter in
inches, multiply by the length, and then by .0034.
In making patterns for aluminum castings provision must be made for
shrinkage to a greater extent than with any other metal or alloy.
The toughness of aluminum can be increased by adding a small per cent.
of phosphorus.
All alloys of metals having mercury are called _amalgams_.
A sheet of zinc suspended in the water of a boiler will produce an
electrolytic action and prevent scaling to a considerable extent.
Hydrofluoric acid will not affect a pure diamond, but will dissolve all
imitations.
A strong solution of alum put into glue will make it insoluble in water.
A grindstone with one side harder than the other can have its flinty
side softened by immersing that part in boiled linseed oil.
One barrel contains 3-3/4 cubic feet.
One cubic yard contains 7-1/4 barrels.
To find the speed of a driven pulley of a given diameter: Multiply the
diameter of the driving pulley by its speed or number of revolutions.
Divide this by the diameter of the driven pulley. The result will be the
number of revolutions of the driven pulley.
To find the diameter of a driven pulley that shall make any given number
of revolutions in the same time: Multiply the diameter of the driving
pulley by its number of revolutions, and divide the product by the
number of revolutions of the driven pulley.
A piece of the well-known tar soap held against the inside of a belt
while running will prevent it from slipping, and will not injure the
belt.
Boiler scale is composed of the carbonate or the sulphate of lime. To
prevent the formation it is necessary to use some substance which will
precipitate these elements in the water. The cheapest and most
universally used for this purpose are soda ash and caustic soda.
Gold bronze is merely a mixture of equal parts of oxide of tin and
sulphur. To unite them they are heated for some time in an earthen
retort.
Rusted utensils may be cleaned of rust by applying either turpentine or
kerosene oil, and allowing them to stand over night, when the excess may
be wiped off. Clean afterwards with fine emery cloth.
Plaster of paris is valuable for many purposes in a machine shop, but
the disadvantage in handling it is, that it sets so quickly, and its use
is, therefore, very much limited. To prevent quick setting mix a small
amount of arrow root powder with the plaster before it is mixed, and
this will keep it soft for some time, and also increase its hardness
when it sets.
For measuring purposes a tablespoon holds 1/2 ounce; a dessertspoon 1/4
ounce; a teaspoon 1/8 ounce; a teacupful of sugar weighs 1/2 pound; two
teacupsful of butter weigh 1 pound; 1-1/3 pints of powdered sugar weigh
1 pound; one pint of distilled water weighs 1 pound.
Ordinarily, 450 drops of liquid are equal to 1 ounce; this varies with
different liquids, some being thicker in consistency than others, but
for those of the consistency of water the measure given is fairly
accurate.