Mortiser
Encyclopedia
Woodworking
Woodworking is the process of building, making or carving something using wood.-History:Along with stone, mud, and animal parts, wood was one of the first materials worked by early humans. Microwear analysis of the Mousterian stone tools used by the Neanderthals show that many were used to work wood...
machine
Woodworking machine
A Woodworking machine is a machine that is intended to process wood. These machines are usually powered by electric motors and are used extensively in woodworking...
used to cut square or rectangular holes in a piece of lumber
Lumber
Lumber or timber is wood in any of its stages from felling through readiness for use as structural material for construction, or wood pulp for paper production....
, such as a mortise in a mortise and tenon
Mortise and tenon
The mortise and tenon joint has been used for thousands of years by woodworkers around the world to join pieces of wood, 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...
joint.
Square chisel mortiser
The square chisel mortiser (also called hollow chisel mortiser), similar to a drill press in many respects, combines the cutting of a four-sided chisel with the action of a drill bitDrill bit
Drill bits are cutting tools used to create cylindrical holes. Bits are held in a tool called a drill, which rotates them and provides torque and axial force to create the hole. Specialized bits are also available for non-cylindrical-shaped holes....
in the center. The bit clears out most of the material to be removed, and the chisel ensures the edges are straight and clean. This device was invented in 1874 by Robert and Ralph Greenlee (founders of the Greenlee Company
Greenlee
Greenlee Textron is an industrial and electrical tool company headquartered in Rockford, Illinois, USA. It was founded in 1862 by brothers Robert and Ralph Greenlee to manufacture their invention, a drill surrounded by four chisel blades, used in making the pockets for a mortise and tenon joint,...
).
Square chisel mortising bits can also be fitted to normal drill presses using a mortising attachment.
The Greenlee Company still manufactures mortisers, as do a large number of other power tool
Power tool
A power tool is a tool that is actuated by an additional power source and mechanism other than the solely manual labour used with hand tools. The most common types of power tools use electric motors. Internal combustion engines and compressed air are also commonly used...
manufacturers
Woodworking tools manufacturers
This is a list of manufacturers of Woodworking hand tools, hand-held power tools and stationary machines*Altendorf GmbH**Brands: Altendorf**Tools: table saws and panel saws*Black and Decker**Brands: Black and Decker, DeWALT, Delta, Porter-Cable, Elu...
. It is a common tool in the woodshop of professional woodworkers, but because of its specialized nature, many amateur woodworkers would not make enough use of it to justify the moderately high cost and space this tool takes up in the woodshop. Some smaller and less expensive models, suitable for cutting only narrow mortises are available.
Horizontal mortiser (slot mortiser)
A more recent innovation is the horizontal mortiser, which incorporates a routerWood router
A router is a tool used to rout out an area in the face of a relatively hard workpiece, typically of wood or plastic. The main application of routers is in woodworking, especially cabinetry....
mounted statically on its side with the workpiece clamped to a multi-axis sliding table. This type of mortiser can produce either traditional mortise and tenon
Mortise and tenon
The mortise and tenon joint has been used for thousands of years by woodworkers around the world to join pieces of wood, 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...
pairs, however it excels at floating (or 'loose') tenons. A floating tenon is where both the pieces of wood that are to be joined have aligned mortises cut into them and a separate piece of wood is milled into a fitted tenon which is glued into the two mortises.
Chain mortiser
For cutting larger mortises such as those used in timber frame construction, chain mortisers are commonly used. A chain with cutters (similar to a chainsaw chainSaw chain
The saw chain, or "cutting chain", is a key component of a chainsaw. It consists of steel links held together by rivets, and superficially resembles the bicycle-style roller chain, although it is closer in design to a leaf chain...
) rotating within a frame clamped to the work is successively plunged into the workpiece to mortise out the required volume. The Makita
Makita
Makita Corporation is a Japanese power tool company founded in 1915, and based in Anjō, Japan. Makita is a manufacturer of professional and consumer power tools, and operates factories in Brazil, Canada, China, Japan, Mexico, Romania, UK and USA. Annual turnover is equivalent to US$1.8 billion.-...
7104L is such a tool. These chains are made in varying widths, with numbers of chains in parallel. The teeth are often solid or tipped tungsten carbide
Tungsten carbide
Tungsten carbide is an inorganic chemical compound containing equal parts of tungsten and carbon atoms. Colloquially, tungsten carbide is often simply called carbide. In its most basic form, it is a fine gray powder, but it can be pressed and formed into shapes for use in industrial machinery,...
. They are thus very expensive, sometimes as much as the rest of the mortiser.
Other methods of cutting mortises
Chisel
A chisel is a tool with a characteristically shaped cutting edge of blade on its end, for carving or cutting a hard material such as wood, stone, or metal. The handle and blade of some types of chisel are made of metal or wood with a sharp edge in it.In use, the chisel is forced into the material...
and mallet
Mallet
A mallet is a kind of hammer, usually of rubber,or sometimes wood smaller than a maul or beetle and usually with a relatively large head.-Tools:Tool mallets come in different types, the most common of which are:...
. However, due to the precision of fit required for a mortise and tenon joint, this can be a difficult and time-consuming task.
Other tools such as a router
Wood router
A router is a tool used to rout out an area in the face of a relatively hard workpiece, typically of wood or plastic. The main application of routers is in woodworking, especially cabinetry....
could be used for the task, but the router usually requires special attachments, jigs or templates and the router bit leaves rounded corners that might need to be squared by hand with a chisel. Alternatively, the tenon can be rounded with a rasp
Rasp
A rasp is a tool used for shaping wood or other material. It consists of a point or the tip, then a long steel bar or the belly, then the heel or bottom, then the tang. The tang is joined to a handle, usually made of plastic or wood. The bar has sharp teeth...
to achieve an equally strong joint.
For cutting small mortises, a normal drill bit
Drill bit
Drill bits are cutting tools used to create cylindrical holes. Bits are held in a tool called a drill, which rotates them and provides torque and axial force to create the hole. Specialized bits are also available for non-cylindrical-shaped holes....
can be used. However, for larger mortises, a common type of bit in modern mortisers is a Harry Watt square drill bit, in which a bit with a Reuleaux triangle
Reuleaux triangle
A Reuleaux triangle is, apart from the trivial case of the circle, the simplest and best known Reuleaux polygon, a curve of constant width. The separation of two parallel lines tangent to the curve is independent of their orientation...
cross section is allowed to "wobble" while it rotates within a square with rounded corners (compare to the motion of a Wankel engine
Wankel engine
The Wankel engine is a type of internal combustion engine using an eccentric rotary design to convert pressure into a rotating motion instead of using reciprocating pistons. Its four-stroke cycle takes place in a space between the inside of an oval-like epitrochoid-shaped housing and a rotor that...
). This type of bit removes all but the corners of the material to be removed, leaving very little to be cut by the chisel.
External links
- History of the Greenlee Company - includes the history of the mortiser
- Reuleaux triangle on MathWorld - includes an animation of the action of a Harry Watt square drill bit