A bench dog is an accessory used on a woodworking

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...

 workbench

Workbench

A workbench is sturdy table at which manual work is done. They range from simple flat surfaces to very complex designs that may be considered tools in themselves. Workbenches vary in size from tiny jewelers benches to the huge benches used by staircase makers...

 to allow clamping of wooden items whilst being worked.

At its most basic a bench dog is simply a peg which is installed in a corresponding dog hole in the top of a bench. The holes are arranged in a line perpendicular to the vice

Vise

Vise may refer to:* Miami Vise, a defunct AFL team* Vise , a mechanical screw apparatus* Vise , an architectural element* Venus In-Situ Explorer * The Vise, TV show* Visé, BelgiumPeople with the surname Vise:...

, perhaps three or four inches apart but certainly no further apart than the fully open distance between the vice's jaws.

There is a matching bench dog in the vice so that the woodworker

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...

 can place a bench dog into a suitable dog hole and clamp a piece of timber between the bench dog in the bench and the bench dog in the vice. It is normal to have two rows of holes, with pairs of holes parallel to the vice so that one has four clamping points.

Benches that have a tail vice and a face vice might have two sets of bench dog holes so that it is possible to clamp in this way from either vice.

Bench dogs may be square or round. Round dog holes are easier to make as they are simply drilled into the bench using a suitably sized 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....

. However round dogs do not provide the best gripping surface. Some woodworkers use round dogs which have been flattened on one side to avoid this issue.

Square dog holes may be created using a mortiser

Mortiser

A mortiser or morticer is a specialized woodworking machine used to cut square or rectangular holes in a piece of lumber, such as a mortise in a mortise and tenon joint.-Square chisel mortiser:...

 or by using a chisel

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...

 in the same way that a mortise

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...

 is created. However the most common way to make these holes is to cut a series of dadoes

Dado (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...

 in the edge of one of the boards that will make up the benchtop. When the boards are laminated together to form the benchtop, the dadoes form the square holes that are required.

Bench dogs require some form of friction mechanism to prevent them falling through the dog hole when in use. This may be achieved by the installation of a strip of spring steel or wire on the side of the bench dog, or simply by making the bench dog a tight fit in the hole. There are various commercial dogs available which solve this problem in numerous ways.