Joining Techniques

Snap rivets, countersunk head rivets and pop rivets.

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Rivets

Snap Rivets

  • Round heads
  • Strong joint
  • You have to have access to both sides of the material

Pop Rivets

  • Can be applied from one side of the material
  • Not very strong

Countersunk Head Rivets

  • Important when the surface of the material has to be flat
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Welding 1

Welding

  • Two pieces of metal are melted together- as strong as the parent metal
  • Oxyacetylene- oxygen and acetylene are used as the heat source and a filler rod of the same metal is used to complete the joint
  • Metal Inert Gas (MIG)- the filler rod supplied a current to the arc whilst it is protected from oxidation by an inert gas, sometimes argon.
  • Safety issues

Brazing

  • Joining two mild steels with spelter, (an alloy of copper and zinc)
  • The joint area should be cleaned with an emery cloth
  • Flux should be applied to the joint to prevent oxidation and to allows the spelter to flow
  • Little training needed to untake
  • Care should be taken to ensure oxidation doesn't happen to create a weak joint
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Welding 2

Hard Soldering

  • Similar to brazing but at a lower temperature
  • Low temperatures required
  • Different melting points to enable complex decorative pieces to be produced
  • Weak joints that don't withstand stress
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Chemical Joints

Tensol Cement

  • Used to join thermoplastics
  • Tensol cement is a solvent and melts the thermoplastics when applied
  • The materials should be clamped for 24 hours
  • It is a permanent joint
  • Gives off strong fumes
  • It can cause damage to the surface of the acrylic

Polystyrene Cement

  • Same as Tensol Cement but for polystyrene rather than acrylic
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Adhesives

PVA

  • Wood glue
  • Water soluble
  • Needs 24 hours to set and needs clamps to hold it together
  • The wood needs to be clean and it needs to have no gaps
  • It will stain wood
  • Very strong

Epoxy-resin

  • Thermosetting plastic that goes hard when mixed with a hardener
  • It is an irreversable reaction
  • Takes a few hours to set
  • Produces a very strong bond, is waterproof and is chemical and heat resistant
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Adhesives 2

Contact Adhesives

  • Useful when glueing laminates
  • Instant sticking
  • Gives off toxic fumes
  • Can't be adjusted once stuck

Hot Melt Glue

  • It is a thermoplastic
  • Useful for small model tasks
  • Quick to harden and bond
  • Glue gun can be very hot and the glue can cause blistering if on skin
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