Machinery Repairman

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cross-feed screw and the cross-slide nut. If the backlash is not eliminated, a straight portion will be turned on the work. You can remove the backlash by moving the carriage and tool slightly past the start of the cut and then returning the carriage and tool to the start of the cut. Methods of Boring Tapers Taper boring is usually done with either the compound rest or the taper attachment. The rules that apply to outside taper turning also apply to the boring of taper holes. Begin by drilling the hole to the correct depth with a drill of the same size as the specified small diameter of the taper. This gives you the advantage of boring to the right size without having to remove metal at the bottom of the bore, which is rather difficult, particularly in small, deep holes. For turning and boring tapers, set the tool cutting edge exactly at the center of the work. That is, set the point of the cutting edge even with the height of the lathe centers; otherwise, the taper may be inaccurate. Cut the hole and measure its size and taper using a taper plug gauge and the “cut and try” method. 1. After you have taken one or two cuts, clean the bore. 2. Rub the gauge lightly with chalk (or prussian blue if the taper must be highly accurate). 3. Insert the gauge into the hole and turn it SLIGHTLY so the chalk (or prussian blue) rubs from the gauge onto the surface of the hole. If the workpiece is to be mounted on a spindle, use the tapered end of the spindle instead of a gauge to test the taper. 4. Areas that do not touch the gauge will be shown by a lack of chalk (or prussian blue). 5. Continue making minor corrections until all, or an acceptable portion, of the hole’s surface touches the gauge. Be sure the taper diameter is correct before you turn the taper to its finish diameter. Figure 6-80 shows a Morse standard taper plug and a taper socket gauge. They not only give the proper taper, but also show the proper distance that the taper should enter the spindle. 6-46 SCREW THREADS Much of the machine work performed by a <strong>Machinery</strong> <strong>Repairman</strong> includes the use of screw threads. The thread forms you will be working with most are V-form threads, Acme threads, and square threads. Each of these thread forms is used for specific purposes. V-form threads are commonly used on fastening devices, such as bolts and nuts, as well as on machine parts. Acme screw threads are generally used for transmitting motion, such as between the lead screw and lathe carriage. Square threads are used to increase mechanical advantage and to provide good clamping ability as in the screw jack or vise screw. Each of these screw forms is discussed more fully later in the chapter. We will also discuss cutting threads on an engine lathe. There are several terms used in describing screw threads and screw thread systems that you must know before you can calculate and machine screw threads. Figure 6-81 illustrates some of the following terms: EXTERNAL THREAD: A thread on the outside surface of a cylinder. INTERNAL THREAD: A thread on the inside surface of a hollow cylinder. RIGHT-HAND THREAD: A thread that, when viewed axially, winds in a clockwise and receding direction. LEFT-HAND THREAD: A thread that, when viewed axially, winds in a counterclockwise and receding direction. LEAD: The distance a threaded part moves axially in a fixed mating part in one complete revolution. PITCH: The distance between corresponding points on adjacent threads. Figure 6-80.—Morse taper socket gauge and plug gauge.
SINGLE THREAD: A single (single start) thread whose lead equals the pitch. MULTIPLE THREAD: A multiple (multiple start) thread whose lead equals the pitch multiplied by the number of starts. CLASS OF THREADS: A group of threads designed for a certain type of fit. Classes of threads are distinguished from each other by the amount of tolerance and allowance specified. THREAD FORM: The view of a thread along the thread axis for a length of one pitch. FLANK: The side of the thread. CREST: The top of the thread (bounded by the major diameter on external threads; by the minor diameter on internal threads). ROOT: The bottom of the thread (bounded by the minor diameter on external threads; by the major diameter on internal threads). THREAD ANGLE: The angle formed by adjacent flanks of a thread. PITCH DIAMETER: The diameter of an imaginary cylinder that is concentric with the thread axis and whose periphery passes through the thread profile at the point where the widths of the thread and the thread groove are equal. The pitch diameter is the diameter that is measured when the thread is machined to size. A change in pitch diameter changes the fit between the thread being machined and the mating thread. Figure 6-81.—Screw thread nomenclature. 6-47 NOMINAL SIZE: The size that is used for identification. For example, the nominal size of a 1/2-20 thread is 1/2 inch, but its actual size is slightly smaller to provide clearance. ACTUAL SIZE: The measured size. BASIC SIZE: The theoretical size. The basic size is changed to provide the desired clearance or fit. MAJOR DIAMETER: The diameter of an imaginary cylinder that passes through the crests of an external thread or the roots of an internal thread. MINOR DIAMETER: The diameter of an imaginary cylinder that passes through the roots of an external thread or the crests of an internal thread. HEIGHT OF THREAD: The distance from the crest to the root of a thread measured along a perpendicular to the axis of the threaded piece (also called straight depth of thread). SLANT DEPTH: The distance from the crest to the root of a thread measured along the angle forming the side of the thread. ALLOWANCE: An intentional difference between the maximum material limits of mating parts. It is the minimum clearance (positive allowance) or maximum interference (negative allowance) between such parts. TOLERANCE: The total permissible variation of a size. The tolerance is the difference between the limits of size. THREAD FORM SERIES: Threads are made in many different shapes, sizes, and accuracies.
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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
Page 119 and 120: Downcutting tool: You may grind and
Page 121 and 122: Figure 5-32.—Grinding drill lip c
Page 123: Figure 5-37.—Grinding a twist dri
Page 126 and 127: ways in alignment with the headstoc
Page 128 and 129: Figure 6-4 shows this plate for the
Page 130 and 131: Before you insert a center or tooli
Page 132 and 133: FEED ROD The feed rod transmits pow
Page 134 and 135: lower lever has eight positions, ea
Page 136 and 137: Figure 6-14.—Quick-change toolpos
Page 138 and 139: Figure 6-21.—Three-jaw universal
Page 140 and 141: Figure 6-26.—Cutaway showing the
Page 142 and 143: 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 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 194 and 195: that most index heads have a 40 to
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.
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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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