Before anything can be built, constructed, or manufactured with any degree of accuracy, it must be drawn first.

©Emil Decker, 2009

Drawings may be as simple as a quick sketch made on a piece of scrap paper with a No. 2 pencil or a complex 3-D Computer Aided Drafting model.

©Emil Decker, 2009

Drawings on paper are often scaled to a proportionate size of the original object. Imagine trying to find a piece of paper big enough to draw a house to its full size.

©Emil Decker, 2009

Drawings on computers, however, are often drawn full size or scale within the program, but later adjusted to fit on paper sized to a printer or plotter’s capability.

©Emil Decker, 2009

There are two basic types of scales used to create accurate drawings: Architectural and Engineering. They differ in their uses, and the ratios of their units.

©Emil Decker, 2009

©Emil Decker, 2009

A scale is much like a ruler. It is divided into units, but the units are representative of the full size. For instance, a 1:10 engineering scale would use 1 inch to represent 10 inches, or 10 feet, or even 10 miles.

Engineering scales are either metric or Imperial (English) standard, which uses the inch as the base unit. Each inch represents the ratio listed on the scale being used.

©Emil Decker, 2009

Scales can be flat like a ruler, but most scales are triangular in shape. This allows them to hold a range of calibrated scales.

©Emil Decker, 2009

Often, there is a complementary unit of measurement that goes right to left. Two scales, going in opposite directions yields as many as 11 or 12 different scales on one tool.

Here we see an engineering scale that has a 1:10 ratio. Also, above this scale is one with a 1:30 ratio. Common units also include 1:20, 1:40, 1:50, and 1:60.

©Emil Decker, 2009

American Architect scales are a little harder to read, as they are divided by 1/2, 1/4, 1/8, and 1/16’s of an inch. The standard 1:1 scale is labeled 16. Shown here, you can see the 3/16 scale also.

©Emil Decker, 2009

The standard relationships on an architect scale are 1” = a foot; 1/2”, 1 1/2”, 1/4”, 3/4”, 1/8”, 3/8”, 3/16”, & 3/32” = a foot. Scales do not start at the edge of the tool, but at a point designated “0”.

©Emil Decker, 2009

Since the units on a scale represent feet, there is often a continuation on the opposite side of the zero representing inches. The thickness of a pencil lead can be “inches thick” on very small scales.

©Emil Decker, 2009

European and other countries around the world use metric scales. Since meters are decimal, or base 10, they are easy to work with.

©Emil Decker, 2009