ix INTRODUCTION TO METALWORKING Copyright Goodheart-Willcox Co., Inc. Chapter 9 Hand Tools That Cut 165 9.5.1 Keyway Broaching Small manually operated broaching equipment uses an arbor press to cut keyways in gears, pulleys, and similar components, Figure 9-31. Cutting a keyway in a gear or pulley is a simple broaching operation that can be done in the average metalworking facility. A typical keyway broach set contains an assortment of precision broaches, slotted bushings, necessary shims, instructions, and a lubrication guide. 9.5.2 Broaching Safety When broaching keyways, the following safety pre- cautions must be observed. • Wear approved eye protection. • Never attempt to use the arbor press and broach- ing set while your senses are impaired by medica- tion or other substances. • Confine (tie up or tuck in) long hair and loose clothing. Keep them away from the moving parts. • Remove all rings, bracelets, earrings, wristwatches, and other jewelry prior to working on an arbor press and using the broach set. • Remove all burrs and sharp edges from the metal in which the keyway is to be broached. • Do not attempt to use the keyway broaching tools until you have been instructed in their safe opera- tion. Have your setup approved by your instructor before beginning work. • Handle broaching tools with care. They have multiple sharp cutting edges and can cause seri- ous injury. • Use a brush to remove chips. Never use your fingers. • After the keyway has been cut, remove all sharp edges. • Carefully remove chips and cutting fluid from the broach before returning it to storage. • Wash your hands to thoroughly remove all traces of cutting fluid. Goodheart-Willcox Publisher Figure 9-31. Cutting a keyway using an arbor press to push the broach through the work. Several passes are usually necessary and additional shimming is used to move the cutter into the work the specified distance. Keyway broach Shim Keyway bushing Broaching a Keyway on an Arbor Press To cut a keyway using a typical keyway broach set, first measure the bore into which the keyway is to be cut. Then complete the following steps: 1. Select the bushing that fits the hole and the required broach. SAFETY NOTE Handle the broach with care. Its sharp teeth can cause serious injury to the hand. 2. Place the bushing into the hole and insert the broach. 3. Set the assembly into position on the arbor press, making sure there is ample clearance for the broach to pass through the work. Also, be sure the broach is centered on the arbor press ram. Otherwise, the broach may be damaged by being pushed to one side. A loose or worn arbor press ram can also damage a broach by pushing it to one side. 4. It is important to lubricate the broach as instructed by the broach manufacturer. 5. Push the broach through the workpiece. 6. Clean the broach and insert the second pass shim. 7. Lubricate the broach again, and push it through the work. 8. Repeat the sequence until the keyway is the correct depth. 9. Use a clean cloth to wipe the broach, bushing, and shims clean. Apply a thin coating of oil to prevent rusting and return them to storage. 10. Remove any burrs from the keyway. 106 Modern Metalworking Copyright Goodheart-Willcox Co., Inc. 6.5.7 Electronic Bore Gage An electronic bore gage, Figure 6-56, uses mul- tiple contact points on a head to accurately inspect bore and hole sizes. Special bore gage measuring heads are available to measure grooves and inter- nal threads. The bore gage is capable of measuring in both inches and millimeters. Electronic gages are comparison gages and can be calibrated by using setting rings. Dial and vernier bore gages are also available. 6.5.8 Telescoping Gage A telescoping gage is used with a micrometer to deter- mine internal dimensions, Figure 6-57. Telescoping 7 7 gages are available in sets of six, as well as other com- binations. Sets of six will typically have a measuring range of 5/16″ (7.9 mm) to 6″ ″ (152 mm). ″ Using a Telescoping Gage The following describes how to use a telescoping gage: 1. Compress the contact points (thpressure).telescope e points within one another un der spring 2. Insert the tool into the opening at a very slight angle on exact center. 3. Allow the contact points to expand and lock the tool in position. 4. Straighten the gage in the hole. 5. Check to make sure the tool is properly fitted. A slight drag should be felt on the contact points. No up-and- down or side-to-side movement should be felt. 6. Lock the contact points in place by turning the knob at the end of the handle. 7. Remove the gage a nd make the reading with a micrometer, Figure 6-58 . Sunnen Products Co. Figure 6-56. An electronic bore gaging system. This self-contained unit can make measurements accurate to 0.00001″ and 0.0002 mm. The gaging probes are ″ replaceable and the unit can be connected to a computer for data collection of work in progress. Goodheart-Willcox Publisher Figure 6-57. A telescoping gage is used to measure internal sizes. Goodheart-Willcox Publisher Figure 6-58. After a telescoping gage is removed from the hole, a micrometer is used to determine the size. Step-by-Step Procedures are highlighted throughout the textbook to provide clear instructions for hands-on activities. You can refer back to these procedures easily. INTRODUCTION TO METALWORKING Copyright Goodheart-Willcox Co., Inc. Chapter 7 Layout Work 125 CAUTION Handle the combination set carefully and do not drop it. The square can be ruined if it is dropped or not handled with care. 7.3 Measuring Angles There are a number of angular measuring tools employed in layout work in addition to the protractor head of the combination set. These tools are discussed next. 7.3.1 Protractors, Bevels, and Gages The accuracy required by the job will often determine which tool must be used. The following angular mea- suring tools provide levels of accuracy: • Plain protractorr.varying r When angles do not need to be checked or laid out to extreme accuracy, a plain protractor will prove satisfactory. See Figure 7-18. The head is graduated from 0° to 180° in both directions for easy use. • Protractor depth gage. This tool can be used to measure angles and the depths of holes. See Figure 7-19 . • Universal bevel. A universal bevel, Figure 7-20, is useful for checking, laying out, and transfer- ring angles. Both the blade and stock are slotted, making it possible to adjust the blade into the desired position. A thumbscrew locks it in place. • Vernier protractor r. r When a job requires extreme angular accuracy, the machinist uses a vernier protractor. See Figure 7-21 . This tool enables the user to measure angles to 1/12 of a degree (5 minutes). • Angle blocks . Angle block sets, Figure 7-22, can be used to establish a surface at a specific angle to hori- zontal. A set contains a selection of blocks at various angles. These angle blocks can then be stacked in combination to produce the required angle. Goodheart-Willcox Publisher Figure 7-18. A plain steel protractor can be used to measure or lay out angles requiring only moderate precision. L. S. Starrett Co. Figure 7-19. Protractor depth gages are used to measure angles and depths of holes. L. S. Starrett Co. Figure 7-20. The blade on a universal bevel is adjustable and can be used to lay out and transfer angles. L. S. Starrett Co. Figure 7-21. A vernier protractor is employed to make precise angular measurements. In this application, a protractor is mounted on a height gage. Cautions alert you to practices that could potentially damage equipment or instruments. Safety Notes alert you to potentially dangerous materials and practices.