Marking gauge
From Wikipedia, the free encyclopedia
A marking gauge is used in woodworking and metalworking to mark out lines for cutting or other operations. In metalworking they can be known as a scratch gauge. The purpose of these gauges is to scribe a line parallel to a reference edge or surface. They are used in joinery and sheetmetal operations.
The gauge consists of a beam, a headstock and a marking implement - either a pin, knife, pen or wheel. The headstock slides along the beam and is locked in place via one of a variety of methods, such as a locking screw, cam lever or wedge. The marking implement is fixed to one end of the beam.
The headstock is set so that the distance between it and the marking implement equals the distance from the reference edge to the line to be scribed. The user then holds the headstock tightly against the reference edge or surface and draws the gauge along so that the headstock follows the reference edge, and the marking implement, in contact with the surface to be marked, scribes a line of the desired length.
The marking implement is chosen depending upon the operation to be performed. Some marking gauges have the capability to allow a number of implements to be fitted, others do not and a woodworker will often have a number of different types. A steel pin is used when scribing with the grain. A steel knife is used when scribing across the grain. The pen or pencil is used when the woodworker does not wish the surface to be marred. Generally speaking, the pin and knife are more accurate than the pen or pencil.
The style of gauge which uses a knife instead of a pin is often described as a cutting gauge. Other variations include a panel gauge which has a longer beam and larger headstock for scribing lines that are further from the reference edge. A mortise gauge has two pins that can be adjusted relative to each other at the end of the beam. This gauge is used to scribe two parallel lines simultaneously and is most commonly used to layout for mortise and tenon joinery.
