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that most index heads have a 40 to 1 ratio. One well-known exception has a 5 to 1 ratio (see fig. 7-14). This ratio is made possible by a 5 to 1 gear ratio between the index crank and the dividing head spindle. The faster movement of the spindle with one turn of the index crank permits speedier production. It is also an advantage when you true work or test it for run out with a dial indicator. While this dividing head is made to a high standard of accuracy, it does not permit as wide a selection of divisions by simple indexing. Later in this chapter, we’ll discuss differential indexing that you can do on the 5 to 1 ratio dividing head by using a differential indexing attachment. The dividing head (also called an index head) may also be geared to the lead screw of the milling machine by a driving mechanism to turn the work-as required for helical and spiral milling. The index head may have one of several driving mechanisms. The most common of these is the ENCLOSED DRIVING MECHANISM, which is standard equipment on some makes of plain and universal knee and column milling machines. The enclosed driving mechanism has a lead range of 2 1/2 to 100 inches and is driven directly from the lead screw. Figure 7-15 shows the gearing arrangement used on most milling machines. The gears are marked as follows: Figure 7-14.—Universal spiral dividing head with a 5 to 1 ratio between the spindle and the index crank. 7-10 Figure 7-15.—Enclosed driving mechanism. A= Gear on the worm shaft (driven) B= First gear on the idler stud (driving) C= Second gear on idler stud (driven) D= Gear on lead screw (driving) E and F = Idler gears LOW LEAD DRIVE: For some models and makes of milling machines a low lead driving mechanism is available; however, additional parts must be built into the machine at the factory. This driving mechanism has a lead range of 0.125 to 100 inches. LONG and SHORT LEAD DRIVE: When an extremely long or short lead is required, you can use the long and short lead attachment (fig. 7-16). As with the low-lead driving mechanism, the milling machine must have certain parts built into the machine at the factory. In this attachment, an auxiliary shaft in the table drive mechanism supplies power through the gear train to the dividing head. It also supplies the power for the table lead screw, which is disengaged from the regular drive when the attachment is used. This attachment provides leads in the range between 0.010 and 1000 inches.
INDEXING THE WORK Indexing is done by the direct, plain, compound, or differential method. The direct and plain methods are the most commonly used; the compound and differential methods are used only when the job cannot be done by plain or direct indexing. DIRECT INDEXING Direct indexing, sometimes referred to as rapid indexing, is the simplest method of indexing. Figure 7-17 shows the front index plate attached to the work spindle. The front index plate usually has 24 equally spaced holes. These holes can be engaged by the front index pin, which is spring-loaded and moved in and out by a small lever. Rapid indexing requires that the worm and the worm wheel be disengaged so that the spindle can be moved by hand. Numbers that can be divided into 24 can be indexed in this manner. Figure 7-16.—The long and short lead attachment. 7-11 Figure 7-17.—Direct index plate. 28.209
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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
Page 144 and 145: TRACING ATTACHMENTS A tracing attac
Page 146 and 147: 2. Place the level across the bed a
Page 148 and 149: Figure 6-41.—Aligning lathe cente
Page 150 and 151: Figure 6-45.—Boring center hole.
Page 152 and 153: ends of the mandrel when you press
Page 154 and 155: Figure 6-52.—Centering work with
Page 156 and 157: Figure 6-56.—Work mounted on a ca
Page 158 and 159: FEED is the amount the tool advance
Page 160 and 161: Rough Turning Figure 6-62.—Rough
Page 162 and 163: Square, round, and “V” grooves
Page 164 and 165: Figure 6-69.—Knurled impressions.
Page 166 and 167: machined surfaces that could become
Page 168 and 169: produced by the same amount of seto
Page 170 and 171: cross-feed screw and the cross-slid
Page 172 and 173: When special threads are required b
Page 174 and 175: Figure 6-83.—Acme thread and form
Page 176 and 177: where An example of a pipe thread i
Page 178 and 179: The wire size you should use to mea
Page 180 and 181: Using the Thread-Cutting Stop Becau
Page 182 and 183: Figure 6-96.—Finishing the end of
Page 184 and 185: shown in figure 6-101. Two slots ar
Page 186 and 187: Figure 7-1.—Universal milling mac
Page 188 and 189: A. Spindle G. Spindle speed selecto
Page 190 and 191: with a split clamp to the overarm a
Page 192 and 193: to the table of the milling machine
Page 196 and 197: Rapid indexing is used when a large
Page 198 and 199: or one complete turn plus 36 holes
Page 200 and 201: allows you to index divisions from
Page 202 and 203: from the one in which the pin is in
Page 204 and 205: Figure 7-24.—Side milling cutter.
Page 206 and 207: A. B. C. D. E. Figure 7-32.—Doubl
Page 208 and 209: Figure 7-36.—Inserted tooth face
Page 210 and 211: Figure 7-43.—Sprocket wheel cutte
Page 212 and 213: Figure 7-48.—Stub arbor. or on th
Page 214 and 215: Figure 7-54.—Spring collet chuck
Page 216 and 217: Figure 7-56.—Face milling. FACE M
Page 218 and 219: 11. 12. 13. 14. 15. 16. 17. 18. 19.
Page 220 and 221: A. Lock screw for dog D. End mill B
Page 222 and 223: 8. 9. 10. 11. 12. 13. 14. 15. 16. 1
Page 224 and 225: 11. 12. 13. 14. 15. 16. 17. 18. 19.
Page 226 and 227: Figure 7-71.—Visual alignment of
Page 228 and 229: machine table. You will hold the cu
Page 230 and 231: Figure 7-77.—Boring with a fly cu
Page 232 and 233: Figure 7-79.—Vertical milling att
Page 234 and 235: Table 7-2.—Surface Cutting Speeds
Page 236 and 237: Table 7-4 shows recommended chip lo
Page 238 and 239: Figure 8-2.—A 36-inch vertical tu
Page 240 and 241: 28.194 Figure 8-3.—Refacing a val
Page 242 and 243: 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
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Figure 11-3.—Slant bed for CNC la
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Figure 11-6.—A typical CNC contro
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Figure 11-8.—Continuous-path angl
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CHAPTER 12 METAL BUILDUP CHAPTER LE
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Figure 12-1.—Typical installation
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Figure 12-5.—A typical sandblaste
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Clean, dry air is essential for pro
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It can reduce the amount of masking
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quality assurance function of the p
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pass-fail. In our educational syste
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straighten a shaft, however, always
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Figure 13-4.—Lapping tools. has t
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pipe in which the valve is installe
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Figure 13-10.—Constant-pressure g
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When you install the control valve
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casing wearing rings, impeller wear
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Figure 13-17.—Removing a broken b
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Figure 13-23.—Metal disintegrator
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Figure 13-25.—Portable boring bar
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Figure 14-1.—Cutting specially sh
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For example, use the following proc
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at an angle to each other, as long
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Figure 14-6.—Development of evenl
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Table 14-1.—"K" Factor Table Tabl
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Figure 14-11.—Standard universal
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6. Find the NPD. 7. Find the 8. Fin
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FA - Face angle OD - Outside diamet
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7. Pitch diameter (PD)—This is th
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SELECTING A BEVEL GEAR CUTTER To cu
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Figure 14-20.—Profiling a bevel g
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. Use the following formulas to sol
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Figure 14-25.—Milling machine set
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9. Diametral pitch (DP) METHOD OF M
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explains the classes and the manufa
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GRAINS (irregularly shaped crystals
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Figure 15-2.—Microscopic structur
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Figure 15-5.—Typical structure of
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Figure 15-8.—Grid for heat-treati
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Table 15-3.—Average Cooling Rates
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cases. A wide variety of quenching
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These various temperature arrests o
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known as pearlite, and the A1 tempe
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quickly cooled to and held at a som
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Available information indicates tha
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slowly from the tempering temperatu
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Table 15-4.—Heat-Treating Tempera
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Figure 15-20.—Design of a cam. A.
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In carburized steel, spalling is ca
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used to make positive identificatio
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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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