Test 2

• Three-jaw self-centring (universal) chuck


  • Used to hold circular or hexagonal workpieces
  • Operates by means of a pinion engaging in a gear on the front of which is a scroll, all encased in the chuck body
  • Chuck jaws have teeth which engage in the scroll and are guided in a slot in the face of the chuck body
  • As the pinion is rotated by a chuck key, the scroll rotates, causing all three jaws to move simultaneously and automatically centre the work
• Four-jaw independent chuck


  • Used to hold square, rectangular and irregular-shaped work which cannot be held in the three-jaw self-centring chuck
  • Each jaw is operated independently by means of a screw - the jaws do not move simultaneously
• Types of chuck jaws

  • External gripping type (for holding outside diameter of the workpiece while boring or drilling)
  • Internal gripping type (for holding internal diameter while machining outside diameter eg for tubes and pipes)
• Collet chuck


  • The most accurate means of holding small workpieces in the lathe
  • Consists of a spring collet and a collet attachment which secures and regulates the collet on the headstock spindle of the lathe
  • Used for small walled tubes
• Faceplate


  • A flat, round plate that is mounted to the headstock spindle of the lathe
  • Used for clamping and machining irregularly-shaped workpieces that cannot be successfully held by chucks or mounted between centres
  • Workpiece is either attached to the faceplate using angle plates or brackets, or is bolted directly to the plate
  • Radial slots in the faceplate surface facilitate mounting workpieces
  • Where there is a risk of machining the faceplate, the workpiece must be raised from the surface on parallels before clamping
• Two-point travelling steady


  • Provides support to the workpiece opposite the tool as cutting is carried out along the length of the work
• Three-point fixed steady


  • Used to support work of a larger diameter than can be accepted through the machine spindle and yet requiring work to be carried out at one end
  • Clamped to the machine bed and the points are adjusted so that the workpiece is running true to the spindle centre line before the machining operation is carried out
• Mandrel


  • Used for machining outside diameters with reference to bores which have already been finished
  • The mandrel is nut between the lathe centres and the work is usually held rigidly between
• Cutting tool materials


  • Must possess red hardness/hot hardness (ability to retain hardness at high cutting temperatures)
  • Must have abrasion resistance (wear resistance)
  • Must have toughness (ability to absorb impact without breaking)
• 1. Max cutters


  1. Pilot hole drilled in correct position

  2. Screw inserted with punch and die on either side of sheet

  3. Screw tightened to shear metal and create correctly sized and shaped hole
• Fly press


  • Used to manufacture a punch and die for cutting the same size hole in the same position on multiple components
  • Punch fitted in moving part of press, die clamped to table in line with punch
  • When handle rotated, punch descends and cuts hole in metal sheet
• Bending using fly press


  1. Top tool fixed to moving part, bottom tool fixed to table

  2. Metal bent to angle less than 90 degrees to allow for spring back