Figure 9-30.–Boring bars.Figure 9-31.–Tapers.of large diameter. The head is fitted with a fly cuttersimilar to the one shown in view A of figure 9-30. Thesetscrew with the tapered point adjusts the cutter to theworkTAPERSAlthough you will probably have little need tomachine tapers, we have provided the followingexplanation for your basic knowledge.A taper is the gradual decrease in the diameter of apiece of work toward one end. The amount of taper inany given length of work is found by subtracting the sizeof the small end from the size of the large end. Taper isusually expressed as the amount of taper per foot oflength or taper per inch of length. We will take twoexamples. (See fig. 9-31.)Example l.–Find the taper per foot of a piece ofwork 2 inches long. The diameter of the small end is 1inch; the diameter of the large end is 2 inches.The amount of taper is 2 inches minus 1 inch, whichequals 1 inch. The length of the taper is given as 2 inches.Therefore, the taper is 1 inch in 2 inches of length. In 12inches of length the taper is 6 inches. (See fig. 9-31.)Example 2.–Find the taper per foot of a piece 6inches long. The diameter of the small end is 1 inch; thediameter of the large end is 2 inches.The amount of taper is the same as in example 1,that is, 1 inch. However, the length of this taper is 6inches; hence the taper per foot is 1 inch times 12/6,which equals 2 inches per foot (fig. 9-31).SAFETY PRECAUTIONSIn machining operations, always keep safety inmind, no matter how important the job is or howwell you know the machine you are operating.Listed here are some safety precautions that youMUST follow:1. Before starting any lathe operations, alwaysprepare yourself by rolling up your shirt sleeves andremoving your watch, rings, and other jewelry thatmight become caught while you operate the machine.2. Wear goggles or an approved face shield at alltimes whenever you operate a lathe or when you are neara lathe that is being operated.3. Be sure the work area is clear of obstructions thatyou might fall or trip over.4. Keep the deck area around your machine clearof oil or grease to prevent the possibility of slipping orfalling into the machine.5. Always use assistance when handling largeworkpieces or large chucks.6. NEVER remove chips with your bare hands.Use a stick or brush, and always stop the machine.7. Always secure power to the machine when youtake measurements or make adjustments to the chuck.8. Be attentive, not only to the operation of yourmachine, but also to events going on around it. NEVERpermit skylarking in the area.9. Should it become necessary to operate the lathewhile the ship is underway, be especially safetyconscious. (Machines should be operated ONLY inrelatively calm seas.)9-19