Machinery Repairman

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Each of the aluminum alloys has properties developed specifically for a certain type of application. The hard aluminum alloys are easier to machine than the soft alloys and often are equal to low-carbon steel in strength. ZINC ALLOYS.—Zinc is a comparatively soft, yet somewhat brittle, metal. Its tensile strength is only slightly greater than that of aluminum. Because of its resistance to corrosion, zinc is used as a protective coating for less corrosion-resistant metals, principally iron and steel. Pure zinc has a strong anodic potential. It is used to protect the hulls of steel ships against electrolysis between dissimilar metals caused by electric currents set up by salt water. Zinc plates bolted on the hull, especially near the propellers, decompose quite rapidly, but greatly reduce localized pitting of the hull steel. TIN ALLOYS.—Pure tin is seldom used except as a coating for food containers and sheet steel and in some electroplating applications. Several different grades of tin solder are made by adding either lead or antimony. One of the Navy’s main uses of tin is to make bearing babbitt. About 5 percent copper and 10 percent antimony are added to 85 percent tin to make this alloy. Various grades of babbitt are used in bearings. Each grade may have additional alloying elements to give the babbitt the properties required. LEAD ALLOYS.—Lead is probably the heaviest metal with which you will work. A cubic foot of it weighs approximately 700 pounds. It has a grayish color and is amazingly pliable. It is obtainable in sheets and pigs. The sheets normally are wound around a rod, and pieces can be cut off quite easily. One of the most common uses of lead is as an alloying element in soft solder. DESIGNATIONS AND MARKINGS OF METALS You must understand the standard designations of metals and the systems of marking metals used by the Navy and industry so you can select the proper material for a specific job. There are several different numbering systems currently in use by different trade associations, societies, and producers of metals and alloys. You may find several different designations that refer to a metal with the same chemical composition, or several identical designations that refer to metals with different chemical compositions. The Society of Automotive Engineers, Inc. (SAE), 3-6 publishes Unified Numbering System for Metals and Alloys. It provides a clear and easily understood cross reference from the designation of one numbering system to other systems where a similar metal is involved. Some of the numbering systems that you may need to identify are as following: Aluminum Association (AA) American Iron and Steel Institute (AISI) Society of Automotive Engineers (SAE) Aerospace Materials Specifications (AMS) American National Standards Institute (ANSI) American Society of Mechanical Engineers (ASME) American Society for Testing and Materials (ASTM) Copper Development Association (CDA) Military Specification (MIL-S-XXXX, MIL-N-XXXX) Federal Specification (QQ-N-XX, QQ-S-XXX) The Unified Numbering System lists all the different designations for a metal and assigns one number that identities the metal. This system covers only the composition of the metal and not its condition, quality, or form. Use of the Unified Numbering System by the various metal producers is voluntary, and it could be some time before its use is widespread. Another useful publication is NAVSEA 0900-LP-038-8010, Ship Metallic Material Comparison and Use Guide. The two major systems used for iron and steel are the Society of Automotive Engineers (SAE) and the American Iron and Steel Institute (AISI). The Aluminum Association method is used for aluminum and is discussed later in this chapter. Other nonferrous metals are designated by the percentage and types of elements in their composition. The Navy uses these methods to mark metals so they can be identified readily. Ferrous Metal Designations You should be familiar with the SAE and AISI systems of steel classifications. These systems, which are in common use, have a four- or five-digit number to indicate the composition of the steel. The major difference between them is that the AISI system normally uses a letter before the numbers to show the
process used to make the steel, and the SAE system does not. The letters are B—acid Bessemer carbon steel; C—basic open-hearth or basic electric-furnace carbon steel; and E—electric-furnace alloy steel. The first digit normally indicates the basic type of steel. Table 3-1 shows the SAE numbers with their corresponding alloying elements. The second digit normally indicates a series within the group. The term series usually refers to the percentage of the major alloying element. Sometimes the second digit gives the actual percentage of the chief alloying element; in other cases, the second digit may indicate the relative position of the series in a group without reference to the actual percentage. The third, fourth, and fifth digits indicate the average carbon content of the steel. If the carbon content is less than 1.00 you will have only four digits. The carbon content is expressed in points; for example: 2 points = 0.02 percent, 20 points = 0.20 percent, and 100 points = 1.00 percent. To make the various steels fit into this classification, it is sometimes necessary to vary the system slightly. However, you can easily understand such variations if you understand the system. Let’s look at a few examples. Check them against the number in table 3-1. (1) SAE 1035: The first digit is 1, so this is a carbon steel. The second digit, 0, shows there is no other important alloying element, so this is a PLAIN carbon steel. The next two digits, 35, show that the AVERAGE carbon content is 0.35 percent. There are also small amounts of other elements such as manganese, phosphorus, and sulfur. (2) SAE 1146: This is a resulfurized carbon steel (often called free cutting steel). The first digit indicates a carbon steel. The second digit shows an average manganese content of 1.00 percent. The last two digits show an average carbon content of 0.46 percent. The amount of sulfur added to this steel ranges from 0.08 to 0.13 percent. Manganese and sulfur in this quantity make this series of steel one of the most easily machined steels available. (3) SAE 4017: The first digit, 4, indicates that this is a molybdenum steel. The second digit, 0, indicates there is no other equally important alloying element, so this is a plain molybdenum steel. The last two digits, 17, show that the average carbon content is 0.17 percent. 3-7 Table 3-1.—SAE Numbers with Their Corresponding Alloying Elements Type of Steel SAE Number Carbon Steels 1xxx Plain carbon 10xx Free cutting (screw lock) 11xx High manganese 13xx Nickel Steels 2xxx 3.50% nickel 23xx 5.00% nickel 25xx Nickel-Chromium Steel 3xxx 1.25% nickel, 0.60% chromium 31xx 3.50% nickel, 1.50% chromium 33xx Molybdenum Steels (0.25% molybdenum) 4xxx 1.0% chromium 41xx 0.5% chromium, 1.8% nickel 43xx 2% nickel 46xx 3.5% nickel 48xx Chromium Steels 5xxx Low chrome 51xx Medium chrome 52xx Chromium-Vanadium Steels 6xxx Nickel-Chromium-Molybdenum 8xxx (low amounts) Silicon-Manganese 92xx Other series within the molybdenum steel group are identified by the second digit. If the second digit is 1, the steel is chromium-molybdenum steel; if the second digit is 3, the steel is a nickel-chromiummolybdenum steel; if the second digit is 6, the steel is a nickel-molybdenum steel. In such cases, the second digit does not indicate the actual percentage of the alloying elements, other than molybdenum. (4) SAE 51100: This number identifies a chromium steel (first digit) with approximately 1.00 percent chromium (second digit) and an average carbon content of 1.00 percent (last three digits). The actual chromium content of SAE 51100 steels may vary from 0.95 to 1.10 percent. (5) SAE 52100: This number identifies a chromium steel (first digit) of a higher alloy series (second digit) than the SAE 51100 steel just described. Note, however, that in this case the second digit, 2, merely identifies the series but does NOT show the percentage of chromium. A 52100 steel will actually have from 1.30 to 1.60 percent chromium
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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
Page 12 and 13: 1-2, and 1-3 show some of the commo
Page 14 and 15: You must know the location of tools
Page 16 and 17: The correct way to measure an insid
Page 18 and 19: appropriate sides of the jaws on th
Page 20 and 21: Dial Bore Gauge The dial bore gauge
Page 22 and 23: Gear Tooth Vernier Use a gear tooth
Page 24 and 25: Surface Gauge A surface gauge (fig.
Page 26 and 27: Figure 1-20.—Center gauge. angle
Page 28 and 29: accuracy. They generally come in ma
Page 30 and 31: MICROMETERS is essentially the same
Page 32 and 33: meanings of these terms and the imp
Page 34 and 35: number is shown for roughness heigh
Page 36 and 37: Figure 2-7.—Master roughness scal
Page 38 and 39: Figure 2-11.—Checking surface fin
Page 40 and 41: Figure 2-17.—Laying out a 45-degr
Page 42 and 43: Figure 2-24.—Setting and using a
Page 44 and 45: Figure 2-29.—Bisecting an angle.
Page 46 and 47: prick-punch “witness marks” aro
Page 48 and 49: Figure 2-35.—Filing. The crosshat
Page 50 and 51: keyway broach requires a bushing th
Page 52 and 53: The steps involved in repairing a d
Page 54 and 55: SETTING UP OXYACETYLENE EQUIPMENT T
Page 56 and 57: GREASE IN THE PRESENCE OF OXYGEN UN
Page 58 and 59: Strength metal into thin sheets. Le
Page 60 and 61: and forming into plates, billets, b
Page 64 and 65: with an average carbon content of 1
Page 66 and 67: The manufacturer is required to mak
Page 68 and 69: with that of known specimens. Many
Page 70 and 71: Gray cast iron produces a spark str
Page 72 and 73: Table 3-4.—Major Groups of Plasti
Page 74 and 75: Lathe Operations Lathe operations a
Page 76 and 77: mechanism is also attached to the s
Page 78 and 79: Band Selection and Installation The
Page 80 and 81: File Bands A file band consists of
Page 82 and 83: This prevents sagging of the file b
Page 84 and 85: Figure 4-16.—Butt welder-grinder
Page 86 and 87: paragraphs contain the procedures f
Page 88 and 89: Figure 4-22.—Disk-cutting attachm
Page 90 and 91: Figure 4-26.—Sensitive drill pres
Page 92 and 93: shops are the Morse taper shank, sh
Page 94 and 95: Figure 4-30.—Common types of clam
Page 96 and 97: Figure 4-34.—Two types of counter
Page 98 and 99: andomly follow the straight sides a
Page 101 and 102: CHAPTER 5 OFFHAND GRINDING OF TOOLS
Page 103 and 104: Figure 5-4.—Standard marking syst
Page 105 and 106: DIAMOND WHEELS Diamond grinding whe
Page 107 and 108: WHEEL CARE AND STORAGE It’s easy
Page 109 and 110: allows cutting speeds approximately
Page 111 and 112: 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
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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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