Woodworking joints

[
thumb|Pocket-Hole Joinery being used to assemble a simple 'T-Joint'.] Joinery is that part of woodworking that involves joining together pieces of wood, to create furniture, structures, toys, and other items. Some wood joints employ fasteners, bindings, or adhesives, while others use only wood elements. The characteristics of wooden joints - strength, flexibility, toughness, etc. - derive from the properties of the joining materials and from how they are used in the joints. Therefore, different joinery techniques are used to meet differing requirements. For example, the joinery used to build a house is different from that used to make puzzle toys, although some concepts overlap.

Traditional Joinery

Many traditional wood joinery techniques use the distinctive material properties of wood, often without resorting to mechanical fasteners or adhesives. While every culture in which pieces of wood are joined together to make furniture or structures has a joinery tradition, wood joinery techniques have been especially well documented and celebrated in the Chinese, European, and Japanese traditions. The Japanese and Chinese traditions in particular include hundreds of types of joints, many of which do not use glue or nails. The Chinese have been using this method for the last seven thousand years. [cite book
first=Nancy W.
last= Steinhardt
year= 2002
title=Chinese Architecture
edition= English Ed.
publisher=Yale University Press
location=
pages= p. 7
id= ISBN 0-300-09559-7 ]

Properties of wood

Many wood joinery techniques either depend upon or compensate for the fact that wood is anisotropic: its material properties are different along different dimensions.

trength

Wood is stronger when stressed along the grain (longitudinally) than it is when stressed across the grain (radially and tangentially).

Dimensional Stability

Wood expands and contracts in response to humidity, usually much less so longitudinally than in the radial and tangential directions.

Joinery Effects

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 acrossand along the grain would rip the two apart.When properly constructed, the panel is free to expand, while still supported by the frame.

Materials used for joining

* Joints can be designed to hold without the use of glue or fasteners.
* 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 longitudinal-grain. Animal glue is soluble in water, producing joints that can be disassembled using steam to soften the glue.
* Various mechanical fasteners are used, the simplest being nails and screws. Glue and fasteners can be added together.

Types of joints

Some types of joints used include:
* Biscuit joint
* Bridle
* Butt
* Butterfly
* Dowel
* Coping
* Cope and stick
* Dado (US) or Housing Joint (UK)
* Dougong
* Dovetail
* Finger (US) or box combing (UK)
* Lap (halving joint)
** Cross-lap
** Halved joint
** Dovetail-lap
** End-lap (corner halving joint)
** Middle-lap (Tee halving joint)
* Miter (mitre)
* Mortise and tenon
* Pocket-Hole Joinery
* Rabbet (rebate)
* Scarf (scarph)
* Splice joint
* Tongue and groove
* Frame and Panel (rail and stile)

Images of different types of joints

ee also

* Woodworking
* Cabinet making
* Building construction
* Chinese Wooden Architecture

Footnotes

References

* Bernard Jones (Ed.) (1980). "The Complete Woodworker". ISBN 0-89815-022-1
* Peter Korn (1993). "Working with Wood". ISBN 1-56158-041-4
* Sam Allen (1990). "Wood Joiner's Handbook". Sterling Publishing. ISBN 0-8069-6999-7
* Wolfram Graubner (1992). "Encyclopedia of Wood Joints". Taunton Press. ISBN 1-56158-004-X

External links

* [http://www.diyinfo.org/wiki/Carpentry DIYinfo.org's Carpentry Wiki] - Practical information on creating various wood-working joints