Introduction to Shaping and Assembling Timbers

Welcome! In this chapter, we are going to look at the "Making" part of Design and Technology. We’ve already learned about different types of wood, but how do we actually turn a plank of Oak or a sheet of MDF into a finished product? We will explore the specialist tools used to shape wood, the different ways to join pieces together (fabrication), and how to put everything together (assembly).

Don't worry if some of the tool names sound new—by the end of this page, you’ll be able to distinguish a Mortise from a Mitre with ease!

Shaping Timbers: Wasting and Cutting

Shaping is often called "wasting" because we are removing the parts of the wood we don't want. Here are the specialist processes you need to know:

1. Cutting and Carving

To get your wood to the right size, you need to cut it. Beyond basic saws, we use specialist methods for different effects:

  • Cutting: Using various saws to remove large sections of material.
  • Carving: A traditional method using chisels and gouges to create 3D shapes or decorative patterns in the wood.
  • Rasps and Surforms: These are "rough" shaping tools. A Rasp has individual teeth and is great for wearing down edges quickly. A Surform works like a cheese grater for wood—it’s excellent for shaping curves.

2. Turning (The Lathe)

If you want to make something perfectly round, like a bowl or a table leg, you use a wood lathe. There are two main ways to do this:

  • Between Centres: The wood is held at both ends. This is used for long, thin items like spindles or chair legs.
  • Face Plate: The wood is screwed onto a flat plate at one end only. This is used for wider, flatter items like bowls or plates.

3. Abrading

Abrading is the technical term for sanding. We use glass paper (sandpaper) to smooth the surface of the wood. You always start with a "coarse" grit to remove big bumps and move to a "fine" grit for a silky-smooth finish.

Quick Tip: Always abrade/sand in the direction of the grain. If you sand across the grain, you will leave scratches that show up when you apply a finish!

Fabrication: Joining Wood Together

Fabrication is the process of joining separate pieces of wood to create a structure. In the exam, you may be asked to identify or sketch these wood joints.

Common Wood Joints

  • Butt Joint: The simplest joint where two pieces of wood just meet. It is very weak on its own and usually needs glue and nails.
  • Dowel Joint: Similar to a butt joint, but small wooden pegs (dowels) are glued into holes in both pieces to add strength.
  • Lap Joint: A step is cut into both pieces of wood so they overlap. This provides a larger surface area for glue, making it stronger than a butt joint.
  • Housing Joint: A "trench" or slot is cut into one piece of wood, and the end of the other piece fits inside. This is perfect for shelves in a bookcase.
  • Mitre Joint: Two pieces are cut at a \(45^\circ\) angle to form a \(90^\circ\) corner. You see these on picture frames.
  • Mortise and Tenon: One of the strongest joints. A "square hole" (the Mortise) is cut into one piece, and a "tongue" (the Tenon) is cut on the other to fit inside perfectly.

Did you know? Specialist Mortise machines are used in workshops to cut those square holes quickly and accurately!

Assembly: Fixings and Adhesives

Sometimes glue isn't enough, or we need to be able to take the product apart later. This is where ironmongery and fixings come in.

1. Mechanical Fixings

  • Screws: Provide a very strong grip and can be removed if needed. You usually drill a pilot hole first to stop the wood from splitting.
  • Nailing: A quick way to join wood, often used for backs of cupboards or basic crates.
  • Knock-down (KD) Fittings: Have you ever built IKEA furniture? Those plastic or metal cams and bolts are KD fittings. They allow products to be sold "flat-pack" and assembled easily by the customer using simple tools.
  • Hinges: Used to allow doors or lids to open and close.

2. Adhesives (Glue)

The syllabus requires you to know two main types for timbers:

  • PVA (Polyvinyl Acetate): The most common "wood glue." It is white, soaks into the wood fibres, and dries clear. It creates a very strong bond but needs time to "set" (usually clamped for a few hours).
  • Contact Adhesive: Used for sticking large flat surfaces together (like sticking a veneer to MDF). You apply it to both surfaces, wait for it to become "tacky," and then press them together for an instant bond.

Specialist Construction Techniques

Sometimes we need to change the properties of wood or make it look more expensive than it is. We use these two clever techniques:

Lamination

Lamination involves gluing thin layers of wood (veneers) together and clamping them over a former (a mold). Because the layers are thin, they can bend. Once the glue dries, the wood stays in that curved shape. This is how curved chair legs or skateboard decks are made.

Veneering

Veneering is the process of gluing a thin layer of expensive, beautiful hardwood (like Oak or Mahogany) onto a cheaper base material like MDF or Chipboard. This makes the product look high-end while keeping the cost low and the product stable.

Key Takeaways for Revision

1. Shaping: Use turning for round objects, rasps/surforms for rough shaping, and abrading for smoothing.

2. Joints: Mortise and Tenon is for high strength; Housing joints are for shelves; Mitre joints are for \(45^\circ\) corners.

3. Fixings: PVA is the standard wood glue; KD fittings are for flat-pack furniture.

4. Advanced: Lamination creates curves; Veneering makes cheap wood look expensive.

Common Mistake to Avoid: Don't confuse "shaping" with "finishing." Shaping is changing the actual form of the wood (cutting/carving), while finishing is the final protective layer (like varnish), which is covered in a different chapter!