LEARNING OBJECTIVES INSTRUCTIONAL MATERIALS GUIDE FOR .
Chapter14Cutting Tapers andScrew Threads onthe LatheLEARNING OBJECTIVESAfter studying this chapter, students will be able to:H Describe how a taper is turned on a lathe.H Calculate tailstock setover for turning a taper.H Safely set up and operate a lathe for taper turning.H Describe the various forms of screw threads.H Cut screw threads on a lathe.INSTRUCTIONAL MATERIALSGUIDE FOR LESSON PLANNINGText: pages 241–260Test Your Knowledge Questions,pages 259–260Workbook: pages 77–84Instructor’s Resource: pages 191–206Guide for Lesson PlanningResearch and Development IdeasReproducible Masters:14-1 Angle Measurement andConversion14-2 Tapers (basic information)14-3 Calculating Tailstock Setover(taper per inch given)14-4 Calculating Tailstock Setover(taper per foot given)14-5 Calculating Tailstock Setover(all taper dimensions given)14-6 Screw Thread Forms(formulas included)14-7 Screw Thread Lead and Pitch14-8 Cutting Action of Threading Tools14-9 Three-Wire Method of MeasuringThreads14-10 Test Your Knowledge QuestionsColor Transparencies (Binder/CD only)This chapter can be divided into two segments. Part I should cover cutting tapers on thelathe and Part II should cover cutting screwthreads on the lathe. Copy and distributeReproducible Masters 14-1 and 14-2.Part I—Cutting Tapers on the LatheSet up lathes for demonstration purposes.Demonstrate the various ways tapers can be cuton a lathe.Have students read and study pages 241–250.Review the assignment using ReproducibleMasters 14-3, 14-4, and 14-5 as overhead transparencies and/or handouts. (Answers are locatedon page 193 of this Instructor’s Resource.) Discussthe following: The advantages and disadvantages of thevarious methods used to cut tapers on alathe. How to calculate tailstock setover. Methods used to setover the tailstock. Types of taper attachments and how to setthem. How to measure tapers.191
192Emphasize the safety precautions that mustbe observed when cutting tapers.Part II—Cutting Screw Threads on the LathePrepare a lathe to cut threads. Explain anddemonstrate procedures for cutting threads.Have students read and study pages250–259. Review the assignment after demonstrating how to set up a lathe and cut threads.Discuss the following: Major uses of the screw thread. Screw thread forms. Use ReproducibleMasters 14-6 and 14-7. Review thread nomenclature. Use Reproducible Master 6-7. Setting up a lathe to cut 60 threads. Threading tool cutting action. Use Reproducible Master 14-8. How to use the thread dial. The three-wire method for measuringthreads. Use Reproducible Master 14-9. How to cut Acme threads. How to cut internal threads. Why cutting fluid should be used.Emphasize safety precautions to be observedwhen cutting threads on a lathe. Briefly reviewthe demonstrations. Provide students with theopportunity to ask questions.Technical TermsReview the terms introduced in the chapter.New terms can be assigned as a quiz, homework, or extra credit. The following list is alsogiven at the beginning of the chapter.external threadsinternal threadsmajor diameterminor diameteroffset tailstock methodpitch diametersetovertaper attachmentthread cutting stopthree-wire method of measuring threadsReview QuestionsAssign Test Your Knowledge questions. Copyand distribute Reproducible Master 14-10 orhave students use the questions on pages259–260 in the text and write their answers on aseparate sheet of paper.Machining Fundamentals Instructor’s ResourceWorkbook AssignmentAssign Chapter 14 of the Machining Fundamentals Workbook.Research and DevelopmentDiscuss the following topics in class or havestudents complete projects on their own.1. Make a display board showing large scalemodels of Sharp V, square, and Acme screwthreads.2. Write a paper on how the first screw threadswere made. If possible, include illustrations.3. Demonstrate to the class the proper technique of machining screw threads. Illustratehow the tool can be repositioned after beingresharpened and how to use the 3-wiremethod of measuring threads.TEST YOUR KNOWLEDGEANSWERS, Pages 259–2601. Compound, offset tailstock, taper attachment, tool bit, and reamer. Evaluate list ofadvantages and disadvantages individually.Refer to Figure 14-3.2. When it increases or decreases in diameterat a uniform rate.3. A. 0.250″B. 0.563″C. 15.7 mm4. Making adjustments, assembling parts, transmitting motion, applying pressure, andmaking measurements.5. d. Cut on outside surface of piece.6. f. Cut on inside surface of piece.7. b. Largest diameter of thread.8. a. Smallest diameter of thread.9. e. Diameter of imaginary cylinder thatwould pass through threads at suchpoints as to make width of thread andwidth of space at these points equal.10. c. Distance from one point on a thread to acorresponding point on next thread.11. g. Distance a nut will travel in one completerevolution of screw.12. d. All of the above.13. center gage, fish tail14. thread dial15. 29 16. a. M 0.520″
Chapter 14b. M 0.270″c. M 0.415″d. M 0.509″WORKBOOK ANSWERS,Pages utting Tapers and Screw Threads on the Lathee. All of the above.offset tailstock or tailstock setoverc. Both a and b.micrometer dialLessens pressure on the tail center.Plain taper attachment. Requires the cross-slidescrew to be disengaged from the cross-slidefeed nut. The cutting tool must be advancedby the compound rest feed screw.Telescopic taper attachment. It is not necessaryto disengage the cross-slide feed nut.Can only cut short tapers.Measuring tapers by comparison plug andring gages, etc.Direct measurement of tapers, gage blocks,and sine bar, etc.c. thread cutting stopEvaluate individually. Refer to Section 14.6.4.d. All of the above.1/N (N Number of threads per inch.)b. the reverse of those usedsharpening the cutting tool and positioningit to cut the threadsstart the next cut in the same directionA device on the lathe that indicates when toengage the half-nuts to permit the tool to follow exactly in the original cut.17. the half-nuts are not engaged18. d. Both b and c.19. b. in relation to the centerline of the 4″1.50″0.876 mm175.0 mm57.14 ��ANSWERS FOR REPRODUCIBLEMASTERS14-3 Calculating Tailstock Setover (TPI 066″14-4 Calculating Tailstock Setover (TPF 061″14-5 Calculating Tailstock Setover(all dimensions 556″
194Machining Fundamentals Instructor’s Resource
Chapter 14195Cutting Tapers and Screw Threads on the LatheAngle Measurement and ConversionAngle measured from thecenterline of the workpiece30 60 Measurement of the included angleTaper per Foot withCorresponding AnglesTaper perfootIncludedangleAngle 1/163/413/167/815/1610 17′ 53″0 35′ 47″0 53′ 44″1 11′ 38″1 29′ 31″1 47′ 25″2 5′ 18″2 23′ 12″2 41′ 7″2 58′ 3″3 16′ 56″3 34′ 48″3 52′ 42″4 10′ 32″4 28′ 26″4 46′ 19″0 8′ 57″0 17′ 54″0 26′ 52″0 35′ 49″0 44′ 46″0 53′ 42″1 2′ 39″1 11′ 36″1 20′ 34″1 29′ 31″1 38′ 28″1 47′ 24″1 56′ 21″2 5′ 16″2 14′ 13″2 23′ 10″Table can be used to convert taper per foot into correspondingangles for adjustment of the compound rest.Copyright Goodheart-Willcox Co., Inc.14-1
Copyright Goodheart-Willcox Co., Inc.TailstocksetoverD diameter at large end of taper; d diameter at smallend of taper; l length of taper; L total length of piece.Length of work causes taper to vary even though tailstockoffset remains the same.CL of latheTapers14-2196Machining Fundamentals Instructor’s Resource
Chapter 14197Cutting Tapers and Screw Threads on the LatheCalculating Tailstock SetoverThe tailstock offset must be calculated for each job because the work length plays animportant role in the calculation. Information needed: TPI Taper per inch, L Total lengthof work.Formula: When taper per inch is known, Offset L TPI21. What will be the setover for the following job? Show your work.TPI 0.035″L 8.500″2. What will be the setover for the following job? Show your work.TPI 0.062″L 12.25″3. What will be the setover for the following job? Show your work.TPI 0.009″L 7.625″4. What will be the setover for the following job? Show your work.TPI 0.055″L 10.125″5. What will be the setover for the following job? Show your work.TPI 0.025″Copyright Goodheart-Willcox Co., Inc.L 5.250″14-3
198Machining Fundamentals Instructor’s ResourceCalculating Tailstock SetoverThe tailstock offset must be calculated for each job because the work length plays animportant role in the calculation. When the taper per foot (TPF) is known, it must first beconverted to taper per inch (TPI). The following formula takes this into account.Formula: When taper per foot is known, Offset L TPF241. What will be the setover for the following job? Show your work.TPF 0.123″L 6.330″2. What will be the setover for the following job? Show your work.TPF 0.250″L 9.750″3. What will be the setover for the following job? Show your work.TPF 0.375″L 10.125″4. What will be the setover for the following job? Show your work.TPF 0.312″L 12.75″5. What will be the setover for the following job? Show your work.TPF 0.126″Copyright Goodheart-Willcox Co., Inc.L 6.750″14-4
Chapter 14199Cutting Tapers and Screw Threads on the LatheCalculating Tailstock SetoverThe tailstock setover must be calculated for each job because the work length plays animportant role in the calculation. Often plans do not specify TPI, TPF, or T/mm, but doprovide pertinent information. If inch dimensions are given in fractions, they must beconverted to decimals.Formula: Offset L (D – d)2 l1. What will be the setover for the following job? Show your work.D 2.000″d 1.500″l 6.000″L 10.000″2. What will be the setover for the following job? Show your work.D 1.125″d 0.750″l 3.000″L 9.000″3. What will be the setover for the following job? Show your work.D .875″d 0.500″l 4.000″L 12.000″4. What will be the setover for the following job? Show your work.D 1.375″d 0.937″l 6.000″L 15.00″5. What will be the setover for the following job? Show your work.D 2 1/2″Copyright Goodheart-Willcox Co., Inc.d 1 15/16″l 6 1/8″L 12 1/8″14-5
Pitch1NCopyright Goodheart-Willcox Co., Inc.1Pitch NSHARP “V” THREAD60 PitchPitch dd 0.866N0.167d0.708d0.125P0.866d NAMERICAN NATIONAL UNIFIED(Interchangeable with Unified Thread)d height of sharp “V” threadRounded crestoptional60 d(P)(2)SQUARE THREAD11NPFlat or space 2Pitch (P)(2)PitchScrew Thread Formsd 11NP2d 0.069P2 0.0100.31P14-6KEY:N Number of threads per inchP Pitchd Depth of thread(P)(2)Root 0.71P–0.0052Flat 0.371PPitch ACME THREAD29 (P)(2)Pitch200Machining Fundamentals Instructor’s Resource
Chapter 14Cutting Tapers and Screw Threads on the Lathe201Screw Thread Lead and PitchSingle Thread Screw(Pitch and thread are equal)Double Thread Screw(The lead is twice the pitch)Triple Thread Screw(The lead is three times the pitch)Copyright Goodheart-Willcox Co., Inc.14-7
Copyright Goodheart-Willcox Co., Inc.Cutting threads with a partialprofile insert. The major (outside) diameter of the threadmust be cut to size beforeusing this type insert.When the tool is fed in at a 29 angle, note thatonly one edge is cutting and that the cutting load isdistributed evenly across the edge.Directionof feedDirectionof feedUsing a full-profile insert tocut a thread. A separateinsert is required for eachthread pitch.When fed straight in, note that both edges are cuttingand the weakest part of the tool, the point, is doingthe hardest work.Tip of threadingtool will break offand threads willnot be accurateCutting Action of Threading Tools14-8202Machining Fundamentals Instructor’s Resource
Chapter 14203Cutting Tapers and Screw Threads on the LatheThree-Wire Method of Measuring ThreadsMicrometerPDdMMicrometerGCopyright Goodheart-Willcox Co., Inc.14-9
204Machining Fundamentals Instructor’s ResourceCutting Tapers and Screw Threads on the LatheName: Date: Score:1. There are five ways of machining tapers on a lathe. List them, with their advantages and disadvantages.2. When is a section of material considered tapered?3. Machine adjustments must be calculated for each tapering job. The information given below willenable you to calculate the necessary tailstock setover for the problems given. Show your work inthe space provided.L TPI2L TPFWhen taper per foot is known, Offset 2Formulas: When taper per inch is known, Offset When dimensions of tapered section are known but TPI or TPF is not given,Offset Where:L (D – d)2 lTPI Taper Per Inch TPF Taper Per FootD Diameter at large end of taper d Diameter at small end of taperl Length of taperNote:L Total length of pieceThese formulas, except for the TPF formula, can be used when dimensions are in mm.Problem A: What will the tailstock setover be for the following job?Taper Per Inch 0.125″Copyright Goodheart-Willcox Co., Inc.Total length of piece 4.000″14-10(continued)
Chapter 14Cutting Tapers and Screw Threads on the Lathe205Name:Problem B: What will the tailstock setover be for the following job?D 2.50″ d 1.75″l 6.00″L 9.00″Problem C: What will the tailstock setover be for the following job?D 45.0 mmd 25.0 mm l 175.0 mm L 275.0 mm4. Screw threads are used for many reasons. List five or more important uses. The following questions are of the matching type. Place the letter of the correct explanation inthe space provided.5. External thread.6. Internal thread.7. Major diameter.8. Minor diameter.9. Pitch diameter.10. Pitch.11. Lead.Copyright Goodheart-Willcox Co., Inc.a. Smallest diameter of thread.b. Largest diameter of thread.c. Distance from one point on a thread to acorresponding point on next thread.d. Cut on outside surface of piece.e. Diameter of imaginary cylinder that wouldpass through threads at such points as tomake width of thread and width of spaceat these points equal.f. Cut on inside surface of piece.g. Distance a nut will travel in one completerevolution of screw.14-10(continued)
206Machining Fundamentals Instructor’s ResourceName:12. A groove is cut at the point where a thread is to terminate.It is cut to the depth of the thread and serves to:a. provide a place to stop the threading tool after itmakes a cut.b. permits a nut to be run up to the end of the thread.c. terminate the thread.d. All of the above.e. None of the above.13. The tip of a cutting tool to cut a Sharp V thread issharpened using a to check that it is the correctshape. This tool is frequently called a .12.14. The is fitted to many lathe carriages. It mesheswith the lead screw and is used to indicate when toengage the half nuts to permit the thread cutting tool tofollow exactly in the original cut.14.15. The compound rest is set at when cutting threadsto permit the cutting tool to shear the material betterthan if it were fed straight into the work.15.13.16. The three-wire thread measuring formula for inch-based threads is:M D 3G –Where:1.5155NG Wire diameterD Major diameter of thread (Convert to decimal size).M Measurement over the wiresN Number of threads per inch.Problems: Calculate the correct measurement over the wires for the following threads. Use the wiresize given in the problem. Show your work in the space provided.a. 1/2-20 UNF (wire size 0.032″)b. 1/4-20 UNC (wire size 0.032″)c. 3/8-16 UNC (wire size 0.045″)d. 7/16-14 UNC (wire size 0.060″)Copyright Goodheart-Willcox Co., Inc.14-10
Calculate tailstock setover for turning a taper. Safely set up and operate a lathe for taper turning. Describe the various forms of screw threads. Cut screw threads on a lathe. 191. Emphasize the safety precautions that must be observed when cutting tapers. Part II—Cutting Screw Threads on the Lathe Prepare a lathe to cut threads. Explain and demonstrate procedures for cutting threads. Have .
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instructional materials generally improved students' understanding of concepts and led to high academic achievements . Recommendations were made on how to improve academic performance of Computer students by encouraging the use of instructional materials in teaching-learning Computer. Keywords: Instructional Materials, Teaching-Learning. 1.
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2. INSTRUCTIONAL DESIGN Instructional design is defined by Berger and Kam [1] as ‘the systematic development of instructional specifications using learning and instructional theory to ensure the quality of instruction. It is the process of analysis of learning needs and goals and
Personalized learning refers to instruction in which the pace of learning and the instructional approach are . optimized for the needs of each learner. Learning objectives, instructional approaches, and instructional content (and its sequencing) may all vary based on learner needs. In addition, learning activities are meaningful and relevant
