Mortise and tenon
Encyclopedia
Woodworking joints
Joinery is a 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,...
has been used for thousands of years by woodworkers around the world to join pieces of wood
Wood
Wood is a hard, fibrous tissue found in many trees. It has been used for hundreds of thousands of years for both fuel and as a construction material. It is an organic material, a natural composite of cellulose fibers embedded in a matrix of lignin which resists compression...
, mainly when the adjoining pieces connect at an angle of 90°. In its basic form it is both simple and strong. Although there are many joint variations, the basic mortise and tenon comprises two components: the mortise hole and the tenon . The tenon, formed on the end of a member generally referred to as a rail, is inserted into a square or rectangular hole cut into the corresponding member. The tenon is cut to fit the mortise hole exactly and usually has shoulders that seat when the joint fully enters the mortise hole. The joint may be glued, pinned, or wedged to lock it in place.
This joint is also used with other materials. For example, it is a traditional method for stonemasons and blacksmith
Blacksmith
A blacksmith is a person who creates objects from wrought iron or steel by forging the metal; that is, by using tools to hammer, bend, and cut...
s.
Types of mortise and tenon
A mortise is a cavity cut into a timberTimber
Timber may refer to:* Timber, a term common in the United Kingdom and Australia for wood materials * Timber, Oregon, an unincorporated community in the U.S...
to receive a tenon.
There are several kinds of mortises,:
- Open mortise – a mortise that has only three sides. (See bridle jointBridle jointA bridle joint is a woodworking joint, similar to a mortise and tenon, in that a tenon is cut on the end of one member and a mortise is cut into the other to accept it...
). - Stub mortise – a shallow mortise, in which depth depends on the size of the timber; also a mortise that does not go through the workpiece (as opposed to a "through mortise").
- Through mortise – a mortise that passes entirely through a piece.
- Wedged half-dovetailDovetailDovetail may refer to:* The dovetail joint used in woodworking* The dovetail or "riffle" method of shuffling playing cards* German equatorial mount, or dovetail plate, used to fix a telescope to its mount...
– a mortise in which the back is wider, or taller, than the front, or opening. The space for the wedge initially allows room for the tenon to be inserted; the presence of the wedge, after the tenon has been engaged, prevents its withdrawal. It is sometimes called a "suicide" joint, since it is a "one-way trip". - Through wedged half-dovetail – a wedged half-dovetail mortise that passes entirely through the piece.
A tenon is a projection on the end of a timber
Timber
Timber may refer to:* Timber, a term common in the United Kingdom and Australia for wood materials * Timber, Oregon, an unincorporated community in the U.S...
for insertion into a mortise. Usually the tenon is taller than it is wide.
There are several kinds of tenons:
- Stub tenon - a short tenon; depth depends on the size of the timber; also a tenon that is shorter than the width of the mortised piece so the tenon does not show (as opposed to a "through tenon").
- Tusk tenon - a kind of mortise and tenon joint that uses a wedge-shaped key to hold the joint together.
- Through tenon - a tenon that passes entirely through the piece of wood it is inserted into, being clearly visible on the back side.
- Biscuit tenon - a thin oval shape piece of wood, looks like a biscuit http://www.popularwoodworking.com/article/Biscuit_Joinery_Basics/?print=1
- Teasel tenon - a term used for the tenon on top of a jowled or gunstock post, which is typically received by the mortise in the underside of a tie beam. A common element of the English tying joint.
- Top tenon - the tenon that occurs on top of a post.
- Feather tenon - a round-shouldered machined fillet or feather which is glued into a machine (router) made slot or mortise on each side of the joint.
- Hammer-headed tenonHammer-headed tenonHammer-headed tenon joints are one method that can be used to join curved members of joinery components.The hammer-headed tenon is used to join a curved member to a straight member such as a curved head member to a jamb. The tenon is formed on the jamb and the mortise to receive the tenon is formed...
- a method of forming a tenon joint when the shoulders cannot be tightened with a clampClamp (tool)A clamp is a fastening device to hold or secure objects tightly together to prevent movement or separation through the application of inward pressure...
. - Half shoulder tenon- An asymmetric tenon with a shoulder on one side only. A common use is in framed, ledged and braced doors.
Generally the size of the mortise and tenon is related to the thickness of the timbers. It is considered good practice to proportion the tenon as one third the thickness of the rail, or as close to this as is practical. The haunch, the cut-away part of a sash corner joint that prevents the tenon coming loose, is one third the length of the tenon and one sixth of the width of the tenon in its depth. The remaining two-thirds of the rail, the tenon shoulders, help to counteract lateral forces that might tweak the tenon from the mortise, contributing to its strength. These also serve to hide imperfections in the opening of the mortise.
History
This is an ancient joint and has been found joining the wooden planks of the "Khufu shipKhufu ship
The Khufu ship is an intact full-size vessel from Ancient Egypt that was sealed into a pit in the Giza pyramid complex at the foot of the Great Pyramid of Giza around 2500 BC. The ship was almost certainly built for Khufu , the second pharaoh of the Fourth Dynasty of the Old Kingdom of Egypt...
", a 43.6 m long vessel sealed into a pit in the Giza pyramid complex
Giza pyramid complex
The Giza Necropolis is an archaeological site on the Giza Plateau, on the outskirts of Cairo, Egypt. This complex of ancient monuments includes the three pyramid complexes known as the Great Pyramids, the massive sculpture known as the Great Sphinx, several cemeteries, a workers' village and an...
of the Fourth Dynasty
Fourth dynasty of Egypt
The fourth dynasty of ancient Egypt is characterized as a "golden age" of the Old Kingdom. Dynasty IV lasted from ca. 2613 to 2494 BC...
around 2500 BC. Evidence of these joints has also been found in the 4800 year-old wooden ruins some archaeologists are calling "Noah's Ark" in Ankara.
It has also been found in archaeological sites in the Middle East, Europe and Asia. In traditional Chinese architecture
Chinese architecture
Chinese architecture refers to a style of architecture that has taken shape in East Asia over many centuries. The structural principles of Chinese architecture have remained largely unchanged, the main changes being only the decorative details...
, wood components such as beams, brackets, roof frames and struts were made to interlock with perfect fit, without using fasteners or glues, enabling the wood to expand and contract according to humidity. Archaeological evidence from Chinese sites shows that by the end of the Neolithic
Neolithic
The Neolithic Age, Era, or Period, or New Stone Age, was a period in the development of human technology, beginning about 9500 BC in some parts of the Middle East, and later in other parts of the world. It is traditionally considered as the last part of the Stone Age...
, mortise and tenon joinery
Woodworking joints
Joinery is a 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,...
was employed in Chinese construction.
The thirty sarsen stones of Stonehenge were dressed and fashioned with mortise and tenon joints before they were erected between 2600 and 2400 BC.
See also
- Box jointFinger jointA finger joint or comb joint is a woodworking joint made by cutting a set of complementary rectangular cuts in two pieces of wood, which are then glued...
- DadoDado (joinery)A dado , housing or trench is a slot or trench cut into the surface of a piece of machinable material, usually wood. When viewed in cross-section, a dado has three sides...
- Dovetail jointDovetail jointA dovetail joint or simply dovetail is a joint technique most commonly used in woodworking joinery. Noted for its resistance to being pulled apart , the dovetail joint is commonly used to join the sides of a drawer to the front....
External links
- DIYinfo.org's Timber Joints Wiki - Heaps of practical information on various types of timber joints.