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Joining Materials (Timber (Joints (Butt Joint (Simple but weak, it…

- - - - Simple but weak, it involves gluing two pieces of wood together. That's it. Can be done at two 45 degree angles in corners for decorative purposes (called mitring).
    - - Butt joint with dowels added to reinforce the joint.
    - - Half the material is removed from each piece of material before gluing them together.
    - - Half the material is removed from one of the sides of the joint, then the pieces of wood are glued together. Can be reinforced with nails.
    - - Mortise and tenon is called thus because it comes in two parts. The mortise is a hole drilled/chiselled/machined into one of the blocks of wood. The tenon is where the excess material is removed from the other piece of wood, and the protrusion is the exact size to fit into the mortise. A very strong joint.
    - - A slot the same width as the depth of the other piece of wood is cut into the material - often used to put up shelves.
    - - Elliptical pieces of wood are put into slots cut into two pieces of wood at right angles or side by side. As the glue sets the "biscuits" swell to fill the gap to the same effect as a mortise and tenon joint.
    - - The strongest joint for box construction, a dovetail joint is like a finger joint on one piece of wood - with sloped sides on the fingers - and channels cut into the other piece of wood to accommodate the fingers. Very hard to do by hand but can be done quite easily with the right machinery and tools (or jigs).
  - - - Used to join kitchen units together. Sit inside the hole between the two units with plastic caps into the holes to hide them.
    - - A pronged nut taps into the hole to provide a threaded insert that will take a machine screw.
    - - A metal threaded insert sits in the hole and takes a threaded screw at right-angles to provide extra strength and anchorage.
    - - Plastic blocks available in a range of colours, they allow two screws to be used at right-angles to eachother. Very useful in simple box joints for providing greater structural integrity to corner joints.
- - - - Soft Soldering
        
        Joins metal parts together using a lead-based alloy.
        
        Used for lighter connections such as electrical circuit connections etc.
        
        First, flux is applied to the joint to clean it, then the solder is heated with a metal soldering bit until it 'runs'.
        
        The melted solder is applied to the joint and left to cool.
      - Hard Soldering
        
        Also called brazing.
        
        Used for heavier joints as it forms a stronger join between the metals.
        
        Uses a brass bonding alloy which melts at a much higher temperature than the solder used in soft soldering.
        
        A borax flux is mixed into a paste with water and applied to the joint to clean it.
        
        Then the spelter (alloy) is applied to the joint and heated until orange in colour with a gas torch, melting it around the joint.
      - Silver Soldering
        
        Same as brazing, but uses a silver based alloy.
        
        It is used for more decorative metals, as the spelter melts at a fat lower temperature than in hard soldering.
  - - - Metal Inert Gas Welding (MIG Welding)
        
        A form of electric arc welding, MIG welding involves forming a spark between the electrode and the metals to be welded.
        
        The high temperatures melt the metals, and an inert gas like argon is used to displace the oxygen to prevent flames and oxidation of the metals.
        
        The inert gas used is usually a mixture of CO2 and Argon.
      - Spot Welding
        
        A form of resistance welding
        
        Two electrodes are placed on either side of the metals to be welded and a current passed between them.
        
        The high current creates heat which welds a small spot of the metals.
        
        This can also be done with two wheeled electrodes (called seam welding).
        
        Used in car manufacturing especially as is good for joining thin sheet metals.
      - Gas Welding
        
        Gas welding equipment can be very dangerous and should only be used by trained staff.
        
        A mixture of acetylene gas and oxygen produces a very small, hot flame which melts both the filler rod and the surrounding metal.
- - - - Countersunk
        
        Tightened with a screwdriver, sit flush with the material.
      - Cheese
        
        Tightened with a screwdriver, provide a secure fit for two slightly different sized holes above eachother.
      - Hexagonal
        
        Tightened with a spanner
      - Socket
        
        Tightened with an allen key.
    - - Wing
        
        Protrusions on the side allow the nut to be tightened by hand. Good for temporary joints.
      - Hexagonal
        
        Tightened with a spanner.
    - - Plain
        
        Spread the force out to relive some of the pressure on the nut and material.
      - Spring
        
        Used to prevent a nut from vibrating loose.
  - - - First the rivet is inserted from one side.
      - Then the pin is snapped off on the side it was inserted from.
      - This causes the small head on the underside to swell, forming a head on both sides of the materials.
      - Made from soft mild steel, copper or aluminium.
- - - - White, water based adhesive.
      - Pva soaks into surface of wood and sets once all the water is absorbed.
      - Often stronger than the wood fibres themselves so makes a very strong bond.
    - - Waterproof adhesive.
      - Needs to be mixed to a creamy consistency with water before application.
      - Chemical hardening takes place and it becomes very hard but brittle.
    - - Dissolves the surfaces of the plastics to be joined.
      - Forms a very strong, irreversible bond.
    - - Versatile but expensive adhesive.
      - Will stick most dry, clean materials together.
      - Equal amounts of resin and hardener are mixed together then it is applied to the surfaces.
      - Chemical setting so ends with a very hard, strong bond.
    - - Cheap and safe rubber solution.
      - Gives off a fishy smell when set.
      - Fumes aren't dangerous however.
  - - - Expensive and dangerous to handle.
      - Bonds hard, non-porous materials together.
      - Used in some surgeries to replace sutures.
    - - Sticks to a wide range of materials.
      - Expands to take up the space between poorly fitted parts so can be useful in schools when prototyping.
    - - Molecules in the materials are vibrated under pressure and the heat generated creates an adhesive-free bond.
      - Used for joining injection-moulded parts together.
      - Also used for an alternative for sewing in some synthetic fabrics.