Mechanical Technology Grade 12 Chapter 4 Tools


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This slide show accompanies the learner guide "Mechanical Technology Grade 10" by Charles Goodwin, Andre Lategan & Daniel Meyer, published by Future Managers Pty Ltd. For more information visit our website

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Mechanical Technology Grade 12 Chapter 4 Tools

  1. 3. <ul><li>Handling tools </li></ul><ul><li>Remember the following points: </li></ul><ul><li>Use tools correctly. </li></ul><ul><li>Don’t overload a tool – it may cause the tool to slip or break, resulting in damage and injury. </li></ul><ul><li>Inspect tools for deficiencies before you use them. </li></ul>
  2. 4. <ul><li>Keep tools clean and return them to their proper places. </li></ul><ul><li>Report any tools which show signs of wearing or breaking. </li></ul><ul><li>Properly dress chisels and punches which have curled-over (mushroomed) heads before using them to prevent the mushroomed edge breaking off when hammered. </li></ul><ul><li>Also attend to loose or cracked hammer handles before using them. </li></ul>
  3. 5. <ul><li>The tool should fit over the bolt head or nut with the minimum of free play. </li></ul><ul><li>As far as possible, ‘pull’ the spanner and don’t ‘push’ it. </li></ul><ul><li>When you have to push a spanner, do so with an open hand and push in the direction in which force is applied. </li></ul>
  4. 6. <ul><li>There are four types of spanner: </li></ul><ul><li>open-ended spanners </li></ul><ul><li>ring spanners </li></ul><ul><li>combination spanners </li></ul><ul><li>socket spanners. </li></ul>
  5. 8. <ul><li>A socket is used with various accessories such as: </li></ul><ul><li>a ratchet </li></ul><ul><li>a speed wrench or brace </li></ul><ul><li>various extensions </li></ul><ul><li>power bars </li></ul><ul><li>flexible joints </li></ul><ul><li>universal joints </li></ul>
  6. 9. <ul><li>Plier types include: </li></ul><ul><li>combination pliers </li></ul><ul><ul><li>to keep an object in position, to tighten something or to cut wire. </li></ul></ul><ul><li>diagonal cutting pliers </li></ul><ul><ul><li>for cutting objects such as split pins or wire. </li></ul></ul><ul><li>long-nose pliers </li></ul><ul><ul><li>Used in confined or unreachable spaces </li></ul></ul>
  7. 10. <ul><li>circlip pliers </li></ul><ul><ul><li>outside circlip pliers and the inside circlip pliers are used to remove circlips </li></ul></ul><ul><li>waterpump pliers </li></ul><ul><ul><li>used for larger objects as they can be extended </li></ul></ul><ul><li>vice grip pliers . </li></ul><ul><ul><li>use them to clamp metal objects </li></ul></ul>
  8. 11. <ul><li>We use screwdrivers to loosen or tighten machine screws and self-tapping screws. </li></ul><ul><li>Flat tip screwdriver </li></ul><ul><ul><li>used for general work. </li></ul></ul><ul><li>Phillips screwdriver </li></ul><ul><ul><li>for the cross-headed screws </li></ul></ul>
  9. 12. <ul><li>Used to check for squareness </li></ul><ul><li>The stock is made of steel </li></ul><ul><li>The blade is hardened and tempered </li></ul>
  10. 13. <ul><li>A steel tape is used to measure long lengths. </li></ul><ul><li>The tape is made of spring steel, cast steel or stainless steel </li></ul><ul><li>Tapes vary in length from 2 m up to 50 m and sometimes longer . </li></ul>
  11. 14. <ul><li>Measure lengths up to 300 mm </li></ul><ul><li>Made of spring steel, cast steel or stainless steel </li></ul><ul><li>Do not knock the edges </li></ul>
  12. 15. <ul><li>Used to draw lines on materials </li></ul><ul><li>Made of tool steel </li></ul><ul><li>When a scriber line is not clearly visible, it should be prepared with a cover layer such as an engineer’s blue spray. </li></ul>
  13. 16. <ul><li>Centre punch </li></ul><ul><li>Used to enlarge the pop mark on a surface where a hole has to be drilled </li></ul><ul><li>The enlarged pop mark acts as a guide for the drill </li></ul><ul><li>Made of tool steel and the included angle should be 90°. </li></ul>
  14. 17. <ul><li>Prick punch </li></ul><ul><li>Used to mark or ‘pop’ scribed lines to make them more prominent </li></ul><ul><li>Half of the pop mark will remain, indicating the position of the line, after objects are machined </li></ul><ul><li>Made of tool steel. </li></ul><ul><li>The included angle should be 60° </li></ul>
  15. 18. <ul><li>Ball pein hammers </li></ul>
  16. 19. <ul><li>Hammer heads </li></ul><ul><li>made of carbon steel or cast steel that contains approximately 0,6% carbon </li></ul><ul><li>classified according to the mass of the head which varies from 250g to 1 kg </li></ul><ul><li>face and pein are hardened and tempered </li></ul><ul><li>The striking face is used for driving blows and the pein for riveting. </li></ul>
  17. 20. <ul><li>The cheek of a hammer is left untempered to maintain its tenacity. </li></ul><ul><li>If hardened, it could easily crack or break </li></ul><ul><li>TENACITY - not easily disconnected: holding together tightly or fused solidly </li></ul>
  18. 21. <ul><li>The hole or eye, in which the shaft fits, is tapered </li></ul><ul><li>This allows the end of the shaft to expand when a wedge is driven into the shaft </li></ul><ul><li>The wedge is made of steel or hard wood </li></ul><ul><li>The shaft must be well-seasoned, straight-grained wood without knots </li></ul><ul><li>Ash or hickory wood is normally used because of its ability to absorb shock </li></ul>
  19. 22. <ul><li>Head of these hammers is made of copper, lead, leather, rubber or plastic </li></ul><ul><li>Most of these heads are replaceable. </li></ul><ul><li>Used to knock on finished surfaces which should not be damaged </li></ul>
  20. 23. <ul><li>A hacksaw is used to cut metals and composites </li></ul>
  21. 24. <ul><li>Hacksaw frame :- Fixed or Adjustable type </li></ul><ul><li>Hacksaw handle :- straight or pistol-grip type </li></ul><ul><li>Hacksaw blade-holder </li></ul><ul><ul><li>threaded square section with wingnut to tighten the blade </li></ul></ul><ul><ul><li>blades fits over other end which has a peg, </li></ul></ul><ul><ul><li>Hacksaw blade </li></ul></ul><ul><ul><ul><li>High speed steel blades are used on harder metals </li></ul></ul></ul><ul><ul><ul><li>Medium carbon steel blades are used on softer metals such as copper </li></ul></ul></ul>
  22. 25. <ul><li>Temper </li></ul><ul><ul><li>the degree of hardness of a metal </li></ul></ul><ul><li>Set </li></ul><ul><ul><li>to become bent from strain </li></ul></ul><ul><li>Tooth size </li></ul><ul><ul><li>E xpressed in the term ‘teeth per 25 mm’ </li></ul></ul><ul><li>Length </li></ul><ul><ul><li>measured between the outside edges of the holes in the blade </li></ul></ul>
  23. 26. <ul><li>TEMPER </li></ul><ul><li>All hard </li></ul><ul><ul><li>The entire blade is hardened </li></ul></ul><ul><ul><li>for accurate work </li></ul></ul><ul><ul><li>relatively brittle and expensive </li></ul></ul><ul><li>Tooth-hardened </li></ul><ul><ul><li>Only the teeth are tempered and the blade is flexible </li></ul></ul><ul><ul><li>for workers who must still develop their skills. </li></ul></ul>
  24. 27. <ul><ul><li>Prevents binding in the saw-cut and the blade breaking </li></ul></ul><ul><li>Teeth are set to saw a wider cut than the blade thickness </li></ul><ul><ul><li>Alternately:- set slightly outward to the left and right </li></ul></ul><ul><ul><li>Wavy Pattern:- groups of teeth are set to the left and right </li></ul></ul><ul><ul><li>:- used on blades with fine teeth. </li></ul></ul>
  25. 28. <ul><li>The frame must be in a good condition </li></ul><ul><li>The correct blade must be chosen. </li></ul><ul><li>Fit blade with the teeth pointing away from handle. </li></ul><ul><li>Ensure that the tension of the blade is correct. </li></ul><ul><li>Clamp the work piece firmly and start cutting </li></ul><ul><li>on a flat surface. </li></ul><ul><li>Saw with long even strokes and apply slight pressure . </li></ul><ul><li>Use the full length of the saw. </li></ul><ul><li>The number of strokes should not exceed 60 per minute </li></ul>
  26. 29. <ul><li>Skew sawing motion </li></ul><ul><li>Incorrect tension </li></ul><ul><li>Cutting at a sharp angle </li></ul><ul><li>Metal not firmly clamped </li></ul><ul><li>Blade binding in the cut. </li></ul>
  27. 31. <ul><li>A cutting tool that has surfaces with sharp tooth-edges </li></ul><ul><li>Use a file to reduce objects to a particular size or shape </li></ul><ul><li>Made of cast steel </li></ul><ul><ul><li>the blade is left very hard while </li></ul></ul><ul><ul><li>the tang is left soft to prevent it from snapping under the pressure of filing </li></ul></ul>
  28. 32. <ul><li>Files are graded and classified according to their :- </li></ul><ul><ul><li>Length </li></ul></ul><ul><ul><ul><li>end of the shoulder to the other end.(blade) </li></ul></ul></ul><ul><ul><li>Section </li></ul></ul><ul><ul><ul><li>Half-round files, Three-square files & Square files etc. </li></ul></ul></ul><ul><ul><li>Cut </li></ul></ul><ul><ul><ul><li>Single-cut files, Double-cut files & Rasps </li></ul></ul></ul><ul><ul><li>and degree of coarseness </li></ul></ul><ul><ul><ul><li>rough, bastard, second-cut and smooth files </li></ul></ul></ul>
  29. 33. <ul><li>Single-cut files </li></ul><ul><ul><li>Teeth are cut parallel to one another, across its surface, </li></ul></ul><ul><ul><li>Angle of cut is approximately 65° to the axis of the file. </li></ul></ul><ul><ul><li>It is recommended for working on soft metal such as copper, lead and brass. </li></ul></ul>
  30. 34. <ul><li>Double-cut files </li></ul><ul><ul><li>Has a second series of parallel teeth cut in the opposite direction to the first set of teeth. </li></ul></ul><ul><ul><li>The first set is cut at about 45° and the other set is cut at between 70° and 80° to the axis of the file. </li></ul></ul><ul><ul><li>These files are used for general work. </li></ul></ul><ul><li>Rasps </li></ul><ul><ul><li>The teeth on a rasp are course and large. </li></ul></ul><ul><ul><li>Rasps are used for filing very soft materials such as wood and leather. </li></ul></ul>
  31. 35. <ul><li>Flat files </li></ul><ul><ul><li>rectangular and its width is parallel for about two-thirds of its length; from there, the file tapers in width and thickness. </li></ul></ul><ul><ul><li>These files are always double-cut on the surface and single-cut on the edge </li></ul></ul><ul><ul><li>And are used for general purpose </li></ul></ul>
  32. 36. <ul><li>Square files </li></ul><ul><ul><li>Taper for the last third of their length and are double-cut on all faces. </li></ul></ul><ul><ul><li>They are used for filing corners, slots and square holes. </li></ul></ul><ul><li>Round files </li></ul><ul><ul><li>Taper like the square file and are mostly single-cut for lengths of up to 150 mm. (Rough and bastard types are used for longer lengths and are double-cut.) </li></ul></ul><ul><ul><li>They are used for opening out holes and for filing round corners. </li></ul></ul>
  33. 37. <ul><li>Half-round files </li></ul><ul><ul><li>Usually double-cut on the flat face, and single-cut on the curved surface. </li></ul></ul><ul><ul><li>This section is not quite semi-circular, and it tapers the last third of its length, both in width and thickness. </li></ul></ul><ul><ul><li>They are used for filing corners less than 90° and concave surfaces. </li></ul></ul><ul><li>Three-square files </li></ul><ul><ul><li>Usually double-cut, and taper to a point. </li></ul></ul><ul><ul><li>They have three 60° corners and are used to sharpen saw-teeth and to file corners less than 90°. </li></ul></ul>
  34. 38. <ul><li>Knife-edge files </li></ul><ul><ul><li>Two faces are double-cut while their edges are single-cut. </li></ul></ul><ul><ul><li>Used for filing or cleaning out sharp corners. </li></ul></ul><ul><li>File handles </li></ul><ul><ul><li>Made of wood (or plastic) with a steel ferrule at the ends. </li></ul></ul><ul><ul><li>Different sizes are available to suit the size of the file. </li></ul></ul><ul><ul><li>Always ensure that the file tang fits tightly into the handle, as a file with a loose handle is liable to cause serious injury. </li></ul></ul>
  35. 39. <ul><li>A chisel is used for removing metal that cannot be removed conveniently by a machine. </li></ul><ul><li>The length of the chisel, its selection and shape depend on the particular work for which it’s needed. </li></ul><ul><li>Chisel materials </li></ul><ul><ul><li>Chisels are made of hardened and tempered cast steel, and are of octagonal section (from an eight-sided steel bar). </li></ul></ul>
  36. 40. <ul><li>Cutting angles </li></ul><ul><ul><li>Ground on the emery wheel, the cutting angle being determined by the metal to be chipped. </li></ul></ul><ul><ul><li>Harder the metal = greater the cutting angle. </li></ul></ul><ul><ul><li>The following angles are recommended for chipping various metals: </li></ul></ul><ul><ul><ul><li>aluminium: 35° </li></ul></ul></ul><ul><ul><ul><li>copper and brass: 40° </li></ul></ul></ul><ul><ul><ul><li>wrought iron and mild steel: 50° </li></ul></ul></ul><ul><ul><ul><li>cast iron: 60° </li></ul></ul></ul><ul><ul><ul><li>cast steel: 70°. </li></ul></ul></ul>
  37. 41. <ul><li>Cutting angles </li></ul><ul><ul><li>Take care not to over-heat a chisel while it is being ground as temper will be taken out, and the degree of hardness reduced. </li></ul></ul>
  38. 42. <ul><li>Flat chisels </li></ul><ul><ul><li>The flat chisel (cold chisel) is most commonly used for general dressing, chipping and cutting. </li></ul></ul><ul><ul><li>The cutting edge should be slightly convex as this prevents damage to the outer corners and gives a longer life to the chisel. </li></ul></ul>
  39. 43. <ul><li>Crosscut chisels </li></ul><ul><ul><li>A crosscut chisel is used for cutting grooves, slots, recesses and keyways </li></ul></ul><ul><li>Round nose chisels </li></ul><ul><ul><li>The straight type is used for drawing over drill centres, in drilling and cutting oil grooves along flat or convex surfaces such as slides, bearings, etc. </li></ul></ul><ul><ul><li>The curved type is used for cutting oil grooves along the curved surface of a bearing. </li></ul></ul>
  40. 44. <ul><li>Diamond point chisels </li></ul><ul><ul><li>A diamond point chisel is used mainly for finishing off and cleaning out corners, and for cutting ‘V’ grooves. </li></ul></ul>
  41. 45. <ul><li>When chipping, watch the cutting edge and not the head of the chisel. </li></ul><ul><li>Place a suitable guard in front of the work to protect others from injury. </li></ul><ul><li>Wear goggles to protect your eyes. </li></ul><ul><li>Dress the head of the chisel when it becomes mushroomed or ragged as the chips that may break off are liable to cause serious injury. </li></ul>
  42. 46. <ul><li>Assessments for this chapter are found on pages :- </li></ul><ul><ul><li>36 to 41, 43, 45 & 47 </li></ul></ul><ul><li>Please prepare for a class test. </li></ul>