How to Connect Things

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How to Connect Things

• Rob Shanahan
• Feb. 6, 2006

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Riveting

• Simplest and most common is the pop rivet
• Installed into a pre-drilled hole using a hand
  tool
• Can be installed into blind holes
• The most common types are not suitable for
  structural use

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Riveting, cont.

• Use rivets that are 1.5x as long as the thickness
  of the material you are joining
• For structural applications, use the Cherry Q
  type rivets
• McMaster-Carr has a good selection

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Riveting, cont.
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Riveting, cont.

• Solid AD rivets are the classic structural
  rivet, but require some special tools to install
• I have never seen them used on a student project
• Cannot be installed into a blind hole, you must
  have access to the back side

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Welding

• Metal is heated above its melting temp. and
  filler rod is added to build up joint area
• Heat can be from oxy-acetylene torch or electric
  arc
• The problem is that the joint area is now a
  brittle casting

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Welding, cont.

• Gas welding is easy , but a large area is heated
• Arc welding (stick) is for ships and emergencies
• MIG (Metal Inert Gas) feeds wire into weld area
  and covers it with inert gas
• Portable and easy, but not very pretty

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Welding, cont.

• TIG (Tungsten Inert Gas) uses inert gas blanket
  and requires the welder to add filler rod
• It is the most flexible welding method we have
  access to
• Heats a small area, and inert gas keeps the weld
  from oxidizing

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Brazing

• Typically uses a gas torch to heat steel to a
  temp. below its melting point, then low temp.
  filler rod is applied
• The result is a joint that is tougher and more
  fatigue resistant than a weld
• Commonly used to repair road cars in Mexico,
  where the roads are rough

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Brazing, cont.

• Nickel Bronze brazing is a very specialized form
  of brazing, actually superior in strength to a
  weld in mild steel
• Requires special rod, flux, equipment, and skill
• Only used on the most expensive tube frame race
  cars

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Bonding

• Sometimes the only way to join dissimilar
  materials-steel and aluminum
• Good practice to apply adhesive to any riveted
  joint
• Bonded joints are good in tension and shear, but
  weak in peel
• Both McMaster-Carr and Aircraft Spruce are good
  sources for the best glues

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Composites

• Consist of fibers or strands encapsulated in a
  plastic matrix
• Fiberglass, Kevlar, and Carbon Fiber can be used
  with either polyester or epoxy
• Very high stiffness to weight ratios
• Outside of my area of expertise, but deserving of
  a separate lecture