Joinery
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Joinery is the part of woodworking that involves the joining together of parts of wood.
Some types of joints used include:
- butt
- dowel
- dovetail
- finger
- lap (halving joint)
- cross-lap
- dovetail-lap
- end-lap (corner halving joint)
- middle-lap (Tee halving joint)
- miter (mitre)
- mortise and tenon
- rabbet (rebate)
- scarf (scarph)
- tongue and groove
- box combing
- numerous forms of dovetail joint.
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Styles of Joinery
Two of the most common traditions of joinery are Chinese and European. Chinese in particular developed hundreds of types of joints and their furniture was often held together without glue or nails. There are also different types of joinery for different structures, for example the joinery used to build a house is different from that used to make puzzle toys, although elements overlap.
Design of Wood Joints
Traditional wood joinery techniques address the distinctive material properties of wood without resorting to mechanical fasteners.
Wood is anisotropic: its material properties are different along different dimensions. It is strong when stressed along the grain (longitudinally), but weak across it (radially and tangentially). It expands and contracts in response to humidity. This change is very small longitudinally. It is considerable, but unequal, in the radial and tangential directions. The frame and panel constructions of doors and cabinets is not purely decorative. The panel would be fragile without the support of the rails, whose grain runs perpendicular to that of the panel. But, if the rails were directly fastened to the panel, the difference in the rate of expansion across and along the grain would rip the two apart. When properly constructed, the panel is free to expand, while still supported by the frame.
Glue is highly effective for joining wood when both surfaces of the joint are edge grain. A properly glued joint may be as strong as a single piece of wood. However, glue is ineffective on end-grain surfaces. Compared to a mortise and tenon, a dowel joint is a poor joint because it does not address these properties. Much of the surface of the hole of a dowel joint is end-grain, to which glue adheres poorly. In a mortise and tenon, most of the surface of the joint is edge-grain.
See also
References
- The Complete Woodworker. Bernard Jones (Ed.) (1980) ISBN 0-89815-022-1
- Working with Wood. Peter Korn. (1993) ISBN 1-56158-041-4