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Design & Technology

Components, joints and adhesives

Joining wood

The method used for joining wood will depend on the function, strength and quality of the product.

Wood joints can be made with screws, nails, glues and knock-down [knock-down: Joint made up of separate components which are designed to be easily assembled and disassembled. ] components, or with frame joints, such as butt joints, halving joints, mortice-and-tenon, dovetail and box joints.

Screws

A screw has a long, winding thread.

Two sizes of hole are needed. The clearance hole must be very slightly bigger than the shank [shank: Smooth, narrow part between the head and core of a screw. ] of the screw so that the shank can move freely in the clearance hole. The pilot hole must be smaller than the core [core: Working part of a screw in which the screw thread is cut. ] of the screw so that the core fits tightly into it.

Nails

Three metal nails, with no thread and a sharp point.

Nails are cheaper and easier to use than screws and come in many shapes and sizes. Holes need to be drilled to prevent the wood from splitting, or when using hard woods.

Knock-down joints

Two pieces of wood are fixed together using a knockdown joint

Knock-down (KD) joints are commonly used in flat-pack furniture, which is assembled by the customer at home. Usually KD joints are made from a plastic, such as nylon.

Frame joints

Strong, permanent and neat-looking joints in wood are achieved using one of the many types of frame joint. Frame joints are right-angled, jointed frames common in furniture, boxes and many other types of assembly.

Simple frame joints

Butt joint, dowelled joint, corner halving, through housing joint

More complex frame joints

Mortise and tenon - a hole in a piece of wood and another piece that fits into the hole. Dovetail joint - interlocking pieces of wood end with triangular shapes. box joint - interlocking pieces of wood end with square shapes

Edging

Chipboard edged with a piece of wood

Lipping is a strip of wood used to reinforce a joint, or to make the edge of a piece of wood look neater.

With floorboards or timber cladding, the edge of a thin strip of wood fits into a slot in the next piece of wood. This is called a tongue-and-groove joint.

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