A marking gauge, also known as a scratch gauge, is used in

woodworking Woodworking is the skill of making items from wood, and includes cabinet making (cabinetry and furniture), wood carving, joinery, carpentry, and woodturning. History Along with stone, clay and animal parts, wood was one of the first mate ...

and

metalworking Metalworking is the process of shaping and reshaping metals to create useful objects, parts, assemblies, and large scale structures. As a term it covers a wide and diverse range of processes, skills, and tools for producing objects on every scal ...

to mark out lines for cutting or other operations. The purpose of the gauge is to scribe a line parallel to a reference edge or surface. It is used in

joiner A joiner is an artisan and tradesperson who builds things by joining pieces of wood, particularly lighter and more ornamental work than that done by a carpenter, including furniture and the "fittings" of a house, ship, etc. Joiners may work in ...

y and sheetmetal operations. The gauge consists of a beam, a headstock, and a scribing or marking implement, typically a

pin A pin is a device used for fastening objects or material together. Pin or PIN may also refer to: Computers and technology * Personal identification number (PIN), to access a secured system ** PIN pad, a PIN entry device * PIN, a former Dutch ...

knife A knife ( : knives; from Old Norse 'knife, dirk') is a tool or weapon with a cutting edge or blade, usually attached to a handle or hilt. One of the earliest tools used by humanity, knives appeared at least 2.5 million years ago, as evidence ...

pen A pen is a common writing instrument that applies ink to a surface, usually paper, for writing or drawing. Early pens such as reed pens, quill pens, dip pens and ruling pens held a small amount of ink on a nib or in a small void or cavity wh ...

or wheel. The headstock slides along the beam, and is locked in place by various means: a locking

screw A screw and a bolt (see '' Differentiation between bolt and screw'' below) are similar types of fastener typically made of metal and characterized by a helical ridge, called a ''male thread'' (external thread). Screws and bolts are used to f ...

cam Calmodulin (CaM) (an abbreviation for calcium-modulated protein) is a multifunctional intermediate calcium-binding messenger protein expressed in all eukaryotic cells. It is an intracellular target of the secondary messenger Ca2+, and the bin ...

lever, or a

wedge A wedge is a triangular shaped tool, and is a portable inclined plane, and one of the six simple machines. It can be used to separate two objects or portions of an object, lift up an object, or hold an object in place. It functions by converti ...

. The marking implement is fixed to one end of the beam.

Types

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 yield more accurate marking than do the pen or pencil. It is also used to mark parallel lines to the face side and edge side.

Variations

The style of gauge which uses a knife instead of a pin is often described as a ''cutting gauge''. This tool is sometimes used to slightly "mark" the wood before a cut to prevent tearout later when doing the main cut with for example a circular saw. 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 lines simultaneously and is most commonly used to lay out mortise and tenon joinery. File:Setting up a marking gauge to 15mm.jpg, Setting a marking gauge to 15mm File:Illustration showing how to use a marking gauge.png, Illustration showing a marking gauge in use File:Gramil.jpg, A mortise gauge File:Using a mortise gauge to strike a pair of lines (4).jpg, A mortise gauge being used File:Illustration on using a marking gauge (side view).png, Illustration of a marking gauge in use File:Panel gauge.jpg, A panel gauge, used for marking wide boards and sheet materials.

References

{{Woodworking Metalworking measuring instruments Woodworking measuring instruments