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6. Find the NPD. 7. Find the 8. Find the RPC. 9. Find the lead. 10. Find the change gear. 11. Find the NTCS. 12. Make sure the cutter has the correct DP and cutter number. 13. Find your corrected chordal addendum and chordal thickness. 14. Find your corrected whole depth (WD). 15. Determine what kind of material the sample gear is to be made of. Now you are ready to machine your gear. Use the following hints to manufacture a helical gear: 1. Make all necessary calculations that are needed to compute the dimensions of the gear. 2. Set up the milling machine attachments for machining. 3. Select and mount a gear cutter. Use the formula 4. Swivel the milling machine table to the helix angle for a right-hand helix; face the machine and push the milling machine table with your right hand. For a left-hand helix, push the table with your left hand. 5. Set the milling machine for the proper feeds and speeds. 6. Mount the change gears. Use the gear train ratio formula to determine your change gears. 7. Mount the gear blank for machining. 8. Set up the indexing head for the correct number of divisions. 9. Before cutting the teeth to the proper depth, double check the setup, the alignment, and all calculations. 10. Now you are ready to cut your gear. 11. Remove and deburr the gear. 14-14 Figure 14-12.—Bevel gear and pinion. A. With shafts less than 90° apart B. With shafts more than 90° apart Figure 14-13.—Other forms of bevel gears. BEVEL GEARS Bevel gears have a conical shape (fig. 14-12) and are used to connect intersecting shafts. Figure 14-13, view A, shows an example of bevel gears with shafts set at less than 90°. View B shows those set at more than 90°. There are several kinds of bevel gear designs. We will discuss the straight-tooth design because it is the most commonly used type in the Navy. The teeth are
Figure 14-14.—Development of the mating gear triangle. 14-15 straight but the sides are tapered. The center line of the teeth will intersect at a given point. Bevel gears are usually manufactured on gearcutting machines. However, you will occasionally have to make one on a universal milling machine. This section of the chapter deals with the angle nomenclature of a bevel gear as well as the development of the triangles needed to manufacture one. When two bevel gears whose shaft angles equal 90° are in mesh (fig. 14-14, view A) they form a triangle. It is called the mating gear triangle. The cones (fig. 14-14, view B) that form the basis of the bevel gears are called the pitch cones. These cones are not visible at all on the finished gear, but they are important elements in bevel gear design. The angle that is formed at the lower left-hand corner of the triangle (fig. 14-14, view C) is called the pitch cone angle of the pinion. The altitude of the triangle is called the pitch diameter of the pinion, and its base is called the pitch diameter of the gear. The hypotenuse of the triangle is twice the pitch cone radius. The pitch diameter (gear and pinion), the number of teeth (gear and pinion), and the actual ratio between the gear and the pinion are all in ratio. Therefore, we can use any of these three sets to find the pitch cone angle (PCA). Example: A 10 diametral pitch (DP) gear with 60 teeth has a pitch diameter (PD) of 6 and a 10 DP pinion with 40 teeth has a PD of 4. Therefore, the ratio of the gear and the pinion is 3:2. We can determine the PCA by simply substituting the known values into the formula: or NOTE: The pitch cone angle of the pinion (PCA p) is the compliment of the pitch cone angle of the gear (PCA g).
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Naval Education and Training Comman
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MACHINERY REPAIRMAN NAVEDTRA 12204-
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PREFACE This Training Manual (TRAMA
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CONTENTS CHAPTER PAGE 1. 2. 3. 4. 5
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Another job description found in pr
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1-2, and 1-3 show some of the commo
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You must know the location of tools
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The correct way to measure an insid
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appropriate sides of the jaws on th
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Dial Bore Gauge The dial bore gauge
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Gear Tooth Vernier Use a gear tooth
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Surface Gauge A surface gauge (fig.
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Figure 1-20.—Center gauge. angle
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accuracy. They generally come in ma
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MICROMETERS is essentially the same
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meanings of these terms and the imp
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number is shown for roughness heigh
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Figure 2-7.—Master roughness scal
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Figure 2-11.—Checking surface fin
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Figure 2-17.—Laying out a 45-degr
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Figure 2-24.—Setting and using a
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Figure 2-29.—Bisecting an angle.
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prick-punch “witness marks” aro
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Figure 2-35.—Filing. The crosshat
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keyway broach requires a bushing th
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The steps involved in repairing a d
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SETTING UP OXYACETYLENE EQUIPMENT T
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GREASE IN THE PRESENCE OF OXYGEN UN
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Strength metal into thin sheets. Le
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and forming into plates, billets, b
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Each of the aluminum alloys has pro
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with an average carbon content of 1
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The manufacturer is required to mak
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with that of known specimens. Many
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Gray cast iron produces a spark str
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Table 3-4.—Major Groups of Plasti
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Lathe Operations Lathe operations a
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mechanism is also attached to the s
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Band Selection and Installation The
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File Bands A file band consists of
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This prevents sagging of the file b
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Figure 4-16.—Butt welder-grinder
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paragraphs contain the procedures f
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Figure 4-22.—Disk-cutting attachm
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Figure 4-26.—Sensitive drill pres
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shops are the Morse taper shank, sh
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Figure 4-30.—Common types of clam
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Figure 4-34.—Two types of counter
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andomly follow the straight sides a
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CHAPTER 5 OFFHAND GRINDING OF TOOLS
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Figure 5-4.—Standard marking syst
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DIAMOND WHEELS Diamond grinding whe
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WHEEL CARE AND STORAGE It’s easy
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allows cutting speeds approximately
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Figure 5-13.—Surface finish vs no
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Figure 5-17.—Boring bars for carb
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Figure 5-19.—Chip breakers. a rad
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Internal-threading tool: The intern
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Downcutting tool: You may grind and
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Figure 5-32.—Grinding drill lip c
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Figure 5-37.—Grinding a twist dri
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ways in alignment with the headstoc
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Figure 6-4 shows this plate for the
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Before you insert a center or tooli
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FEED ROD The feed rod transmits pow
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lower lever has eight positions, ea
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Figure 6-14.—Quick-change toolpos
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Figure 6-21.—Three-jaw universal
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Figure 6-26.—Cutaway showing the
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Figure 6-32.—Thread dial indicato
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TRACING ATTACHMENTS A tracing attac
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2. Place the level across the bed a
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Figure 6-41.—Aligning lathe cente
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Figure 6-45.—Boring center hole.
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ends of the mandrel when you press
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Figure 6-52.—Centering work with
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Figure 6-56.—Work mounted on a ca
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FEED is the amount the tool advance
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Rough Turning Figure 6-62.—Rough
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Square, round, and “V” grooves
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Figure 6-69.—Knurled impressions.
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machined surfaces that could become
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produced by the same amount of seto
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cross-feed screw and the cross-slid
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When special threads are required b
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Figure 6-83.—Acme thread and form
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where An example of a pipe thread i
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The wire size you should use to mea
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Using the Thread-Cutting Stop Becau
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Figure 6-96.—Finishing the end of
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shown in figure 6-101. Two slots ar
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Figure 7-1.—Universal milling mac
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A. Spindle G. Spindle speed selecto
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with a split clamp to the overarm a
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to the table of the milling machine
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that most index heads have a 40 to
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Rapid indexing is used when a large
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or one complete turn plus 36 holes
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allows you to index divisions from
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from the one in which the pin is in
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Figure 7-24.—Side milling cutter.
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A. B. C. D. E. Figure 7-32.—Doubl
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Figure 7-36.—Inserted tooth face
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Figure 7-43.—Sprocket wheel cutte
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Figure 7-48.—Stub arbor. or on th
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Figure 7-54.—Spring collet chuck
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Figure 7-56.—Face milling. FACE M
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11. 12. 13. 14. 15. 16. 17. 18. 19.
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A. Lock screw for dog D. End mill B
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8. 9. 10. 11. 12. 13. 14. 15. 16. 1
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11. 12. 13. 14. 15. 16. 17. 18. 19.
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Figure 7-71.—Visual alignment of
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machine table. You will hold the cu
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Figure 7-77.—Boring with a fly cu
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Figure 7-79.—Vertical milling att
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Table 7-2.—Surface Cutting Speeds
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Table 7-4 shows recommended chip lo
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Figure 8-2.—A 36-inch vertical tu
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28.194 Figure 8-3.—Refacing a val
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HORIZONTAL BORING MILL The horizont
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7. After you have tightened the mou
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The table can be power driven to pr
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CHAPTER 9 SHAPERS, PLANERS, AND ENG
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Figure 9-3.—Swiveled and tilted t
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extent in planer and shaper work To
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the cutting speeds and related mach
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Figure 9-10.—Internal keyway: A.
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7. 8. 9. 10. 11. 12. 13. 14. Replac
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or housing attached on one side of
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Figure 9-18.—Engraving machine. F
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CUTTER SPEEDS The speeds listed in
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can readily see it after grinding t
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Figure 9-29.—Using an indexing at
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Any further movement of the work wi
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Figure 10-1.—Grain depth of cut;
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To select the proper work speed, ta
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Figure 10-8.—Magnetic chuck used
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can do on a surface grinder. Use th
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for straight cylindrical grinding o
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Figure 10-15.—Typical tooth rest
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of the work. Raise or lower the whe
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Figure 10-23.—Staggered-tooth sid
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Figure 10-28.—Grinding the periph
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Once the teeth are uniform, they sh
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After you have honed out the inaccu
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MACHINES With the rapid development
Page 298 and 299: Figure 11-3.—Slant bed for CNC la
Page 300 and 301: Figure 11-6.—A typical CNC contro
Page 302 and 303: Figure 11-8.—Continuous-path angl
Page 304 and 305: CHAPTER 12 METAL BUILDUP CHAPTER LE
Page 306 and 307: Figure 12-1.—Typical installation
Page 308 and 309: Figure 12-5.—A typical sandblaste
Page 310 and 311: Clean, dry air is essential for pro
Page 312 and 313: It can reduce the amount of masking
Page 314 and 315: quality assurance function of the p
Page 316 and 317: pass-fail. In our educational syste
Page 318 and 319: straighten a shaft, however, always
Page 320 and 321: Figure 13-4.—Lapping tools. has t
Page 322 and 323: pipe in which the valve is installe
Page 324 and 325: Figure 13-10.—Constant-pressure g
Page 326 and 327: When you install the control valve
Page 328 and 329: casing wearing rings, impeller wear
Page 330 and 331: Figure 13-17.—Removing a broken b
Page 332 and 333: Figure 13-23.—Metal disintegrator
Page 334 and 335: Figure 13-25.—Portable boring bar
Page 336 and 337: Figure 14-1.—Cutting specially sh
Page 338 and 339: For example, use the following proc
Page 340 and 341: at an angle to each other, as long
Page 342 and 343: Figure 14-6.—Development of evenl
Page 344 and 345: Table 14-1.—"K" Factor Table Tabl
Page 346 and 347: Figure 14-11.—Standard universal
Page 350 and 351: FA - Face angle OD - Outside diamet
Page 352 and 353: 7. Pitch diameter (PD)—This is th
Page 354 and 355: SELECTING A BEVEL GEAR CUTTER To cu
Page 356 and 357: Figure 14-20.—Profiling a bevel g
Page 358 and 359: . Use the following formulas to sol
Page 360 and 361: Figure 14-25.—Milling machine set
Page 362 and 363: 9. Diametral pitch (DP) METHOD OF M
Page 364 and 365: explains the classes and the manufa
Page 366 and 367: GRAINS (irregularly shaped crystals
Page 368 and 369: Figure 15-2.—Microscopic structur
Page 370 and 371: Figure 15-5.—Typical structure of
Page 372 and 373: Figure 15-8.—Grid for heat-treati
Page 374 and 375: Table 15-3.—Average Cooling Rates
Page 376 and 377: cases. A wide variety of quenching
Page 378 and 379: These various temperature arrests o
Page 380 and 381: known as pearlite, and the A1 tempe
Page 382 and 383: quickly cooled to and held at a som
Page 384 and 385: Available information indicates tha
Page 386 and 387: slowly from the tempering temperatu
Page 388 and 389: Table 15-4.—Heat-Treating Tempera
Page 390 and 391: Figure 15-20.—Design of a cam. A.
Page 392 and 393: In carburized steel, spalling is ca
Page 394 and 395: used to make positive identificatio
Page 396 and 397: HONING—Finishing machine operatio
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Table AII-2.—Decimal Equivalents
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Table AII-4.—Formulas for Dimensi
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Table AII-5.—Number, Letter and F
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Table AII-7.—Screw Thread and Tap
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Table AII-9.—3-Wire Method of Mea
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Table AII-11.—Circles Circumferen
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Table AII-13.—Taper Per Foot and
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p 1 I vi 2 P F \ = = a AII-16
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Table AII-16.—Drill Sizes for Tap
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Having Circular pitch Circular pitc
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APPENDIX IV DERIVATION OF FORMULAS
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(1) NT is the connecting link betwe
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Walker, John R., Machining Fundamen
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A Adjustable gauges, 1-7 adjustable
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Engine lathes, 6-1 attachments and
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Layout methods, 2-8 M forming angul
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Stub tooth gears, 14-27 American st
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