5 Scaling

Scaling

  • SCALE MEASUREMENT
  • FULL SIZE
  • HALF SIZE
  • QUARTER SIZE

The ability to make accurate measurements is a basic skill needed by everyone who reads and uses blueprints. This section is intended as a review of the fundamental principles of measurement. Since some students have had little need to measure accurately, these exercises will provide the practice they need. Others, who have had more experience, may find these exercises a worthwhile review.

Whether or not you need to review these fundamentals, there is one important thing to remember about getting measurements from a print. If you need a dimension that is unclear or is not given, do not measure the print! Since prints shrink, stretch, and may not be drawn to scale, you can easily come up with some very inaccurate dimensions.

Scale Measurement

A drawing of an object may be the same size as the object (full size), or it may be larger or smaller than the object. In mo.st cases, if it is not drawn full size, the drawing is made smaller than the object. This is done primarily for the convenience of the users of the drawings. After all, who wants to carry around a full size drawing of a locomotive? Obviously, with an object as small as a wristwatch, it would be necessary to draw to a larger scale.

A machine part, for example, may be half the size (1/2”=1”); a building may be drawn 1/48 size (1/4”=1’-0”); a map may be drawn 1/200 size (1”=100’-0”); and a gear in that wristwatch may be ten-times size (10”=1”).

There are numerous scales for different needs. Since each occupational group has their own frequently used scales, some practice or basics review will help you to work with the scales used in your technology.

Full Scale

Full scale is simply letting one inch on a ruler, steel rule, or draftsman’s scale equal one inch on the actual object. Rules of this kind are usually divided into 1 /16” or 1 /32” units. The first measurement exercise will be with full size. If you can measure accurately in full scale, you may want to skip ahead.

Here is a “big Inch”. Each space equals 1/32”. If you have not worked with accurate measurement, spend some time studying it.

Ruler sample in 32nd scale. The image is a detailed diagram of a ruler marked with fractional measurements from 0 to 1. It features a horizontal line marked by vertical lines of varying lengths indicating fractional divisions. The fractions range from very small increments such as 1/32, 1/16, and 1/8, up to larger increments like 1/4, 3/8, and 1/2, culminating at 1. Each fractional measurement is accompanied by corresponding numerical notation directly above the line. The main markers at 0, 1/2, and 1 are longer than the others for emphasis.

Measurement practice: on the scale above, locate the following fractions:

Written fractions to be located on a scale. The image displays two vertically arranged, numbered lists of fractional measurements. The left column consists of five fractions with numerators and denominators. Similarly, the right column has corresponding fractions with numerators and denominators, aligned with those in the left column.

Directions:

Each of the fractions below is numbered. Write that number above the scale and point with an arrow where the fraction is located. Number 1 has been completed.

 

List of fractions and to be located on the scale. The image displays a section of a ruler marked from 0 to 3 inches. The ruler features detailed fractional increments between each inch mark. Above the ruler, there are twelve numbered fractional measurements in two columns. Each fraction is placed above the ruler and corresponds to a specific point on the ruler marked by a numbered arrow. The arrow from the number "1" fraction (2 3/32) points directly to its position on the ruler.

Half Size

The principle of half size measurements on a drawing is simply letting a unit, such as 1/2” on the scale, represent a larger unit such as 1” on the drawing. If the drawing is properly labeled, the words HALF SIZE or 1/2″= 1′ will appear in the title block.

Using the half-size scale is not difficult, but it does take some practice. To measure a distance of 2-3/16” you look first for the 2, then go backwards to the zero and count off another 3/16. You measure this way for each dimension that has a fraction. Whole numbers (numbers without fractions) are measured in the usual way.

Half size scale example. The image displays a segment of a ruler with markings indicating measurements in inches. The ruler is labeled "HALF SIZE" and starts with a "½" marking, indicating half-inch increments. The ruler displays numbers from 0 to 5, evenly spaced along the bottom. Above the ruler, an arrow illustrates a measurement of "2 3/16" inches, pointing from 0 to a mark slightly beyond 2. The background is white, and the markings are in black for clear visibility.

Written fractions to be located on a scale. The image consists of two vertical columns of numbers, each containing three fractional values listed in numerical order. The left column is numbered 1 to 3 and contains the fractions "4-3/16," "2-1/2," and "5-3/4." The right column is numbered 4 to 6 and repeats these same fractions in the same order.

Next, locate a half size scale (available in the lab) and measure the lines· below to the nearest 1 /32 of an inch. Write the length of the line in the space provided.

Lines that are to be measured and written in the spaces provided. The image features a simple list layout. It consists of six numbered lines, each preceded by a blank line and followed by a longer blank space to the right. The numbers 1 to 6 are vertically aligned on the left side, with each number followed by a period. The longer blank lines parallel to each number create an area for writing or input. The background is plain white, and the text and lines are in black, providing a clear and high-contrast look.

Because paper is dimensionally unstable due to humidity, exact answers to this half size measurement practice cannot be given. That is another reminder that it’s poor practice to measure from a piece of paper.

 

Quarter Size

Quarter size is used and read in a similar way to half size except that each unit, such as a quarter of an inch, represents a larger unit, such as one inch. If the drawing is properly labeled the words QUARTER SIZE, QUARTER.SCALE, or 1/4″ = 1″ will appear in the title block.

The quarter size scale is used in a similar manner as the half size scale.

For quarter size practice, draw lines in the area provided to the required length. Have another student or the lab instructor check your lines for accuracy. (A ¼”=1” scale is available in the lab.)

List of fractions that are to be drawn to the given size. The image is a vertical list of measurements, each prefixed by a number and a period. There are eight entries, each consisting of a numerical measurement followed by the inch symbol ("). Each entry is separated by a horizontal line beneath the number. The text is black, set against a white background, and is formatted in a simple, sans-serif typeface.

Quiz

For this quiz, you will be given an object to measure with a ruler or tape measure. You will record measurements in full scale and then draw each length in ½ and ¼ scale.

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