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Scale Reading Basics

The English Scale The English scale is an instrument that is used to measure linear distances. A typical English scale is made up of 12 inches.

Scale Accuracy The inch is fractioned into smaller increments. Usually, the smallest increment is 1/16 th of an inch. How big is 1/16 th on an inch? You would need to stack about 16 sheets of paper to equal 1/16 th of an inch.

Two sheets of Paper stacked Human hair dia. Paper Clip dia. Proportioned section diagrams 1/128 inch .008 1/32 inch .031 Common Items: Size Comparison 1/256 inch .003

The INCH The divisions on an English scale are easily identified by different sized markings. The largest markings on the scale identify the inch.

The INCH All subsequent sized markings can be found by taking half of the previous measurement. i.e., half of an inch = ½ inch 1/2

The INCH Half of a half = ¼ inch. An English scale shows ¼ inch and ¾ inch marks. All fractions must be reduced to lowest terms. 1/4 3/4

The INCH Half of a quarter = 1/8 inch 1/8 3/8 5/8 7/8

The INCH 1/16 3/16 5/16 13/16 7/16 11/16 9/16 15/16 Half of an eighth = 1/16 inch

Now Let’s practice Question 1: What is the distance of A?

¼” The Fractional answer is: What would be the metric answer? .25 x 25.4= 6.35 or 6mm if rounding to the nearest mm. 6mm

The Metric Scale The metric scale is another instrument that is used to measure linear distances. A typical metric scale is made up of approximately 300 mm.

Scale Accuracy The metric scale is divided into very small increments called millimeters (mm). There are 25.4 mm in one inch.

The Millimeter The millimeter is the smallest increment found on a typical metric scale. 1 mm

The Millimeter The next larger marking on a metric scale shows 5 millimeters. 5 mm

The Millimeter The largest markings on the metric scale represent centimeters (cm). These are the only marks that are actually numbered. 1 cm = 10 mm

Let’s Practice What is the metric answer for B 19mm What would the answer be if converted to inches? ¾”