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Mechanical Technology Grade 12 Chapter 4 Tools
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Mechanical Technology Grade 12 Chapter 4 Tools


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 …

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