The measuring system you choose depends on the working drawings. The title block will indicate what system is used. It will also provide the scale of the drawing. If the scale reads 1″ = 1′-0″, then each inch on the drawing will be 1′ on the layout. Special purpose rules include a centering rule, with the measuring units extending both directions from the center zero point. This reduces the chances for error with many centering tasks. Rigid folding rules are usually 6′ long. Metric folding rules are 2 meters long. Some have an exten- sion rule at one end for measuring inside distances and depths. See Figure 12-7. A flexible rule, or tape measure, is very conve- nient and will measure both straight lengths and curves. See Figure 12-8. It can also be used to mea- sure inside distances, such as a doorway. To account for the size of the tape case, add the distance indi- cated on the side of the case to your measurement. Most tape cases will be printed with the amount you must add (usually 2″–3″). Some tape measures have a window on the top to read the inside distance. Lufkin Division—The Cooper Group The L.S. Starrett Co. Figure 12-7. A—Rigid folding rules extend to measure distances. B—Using the extension to measure inside distances. Lufkin Division—The Cooper Group, The L.S. Starrett Co. Figure 12-6. Rule measuring units. Use the system designated on the working drawings. A—US customary. B—Metric. C—Combination of both units. 3 4 5 6 7 8 9 10 2m 1 2 3 4 UFKIN 10 20 60 70 80 90 100 110 10 20 60 70 80 90 100 110 First foot of scale further divided into 32nds of an inch. 1/16″ 1/8″ 1/4″ 1/2″ A—US Customary Rule B—Metric Rule C—Combination Rule Rest of scale divided into 16ths INS CM 1/2mm mm 1″ 12.2.1 Rule The rule you select depends on the accuracy you need and which style you prefer. Rules may be flat, flexible, or folding types. They are made of wood, fiberglass, plastic, metal, or cloth. Sometimes both customary and metric measurements are found on the same rule. Flat rules are typically metal, wood, or plastic. They may be 12″ to 48″ long. High quality wood rules have brass ends. The brass ends are not damaged as easily as wood. Rules may also be steel or aluminum. 6′ Zigzag Rule 6′ Extension Rule 2m Zigzag Rule A B Green Note The old adage, “measure twice cut once” is good advice. Mistakes will happen. Taking your time to make sure you have correct measure- ments will help you avoid material waste and spending extra time fixing your mistake. Chapter 12 Measuring, Marking, and Laying Out Materials 151 Copyright Goodheart-Willcox Co., Inc.