What are pillar equalling and square edge joint files?

29th February 2020


	What are pillar, equalling and square edge joint files?


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			Pillar files, equalling files and square edge joint files are machinist’s files used for finishing and shaping inside square or rectangular slots, such as key ways or mortises.



			These types of file feature safe edges, which allows for the creation of grooves that are fixed at the same width as the file. This can be particularly useful for professions like instrument making, where the sizes of such slots may need to be kept standard.

			The ability to file inside rectangular slots and level out any inconsistencies is what earned the equalling file its name, as each edge could be made equal by the file.

			What are the characteristics of pillar, equalling and square edge joint files?
			Cross section, profile and cut Pillar files have a rectangular cross section that is narrower but thicker than a hand or flat file.

			The tool earned its name thanks to its cross section. As it is thicker than flat or hand files, when it is turned on its side it bears a resemblance to a pillar.

			They are tapered in thickness and cut on both faces (double or single). Both edges are safe.

			Equalling files are also machinist’s files. They are blunt and rectangular in cross section. They are usually double cut on both faces and single cut on both edges.

			However, it is possible to find equalling files that are only cut on one side. This allows the user to work on just one edge of a slot without having to worry about cutting into another.

			Square edge joint files are blunt and rectangular in cross section. They are cut on the edges, but their faces are safe.

			The location and type of cut are what determine the purpose of these files. Square edge joint files can be used to file the narrow edge deep inside tongue and groove flooring, as their safe faces prevent alteration of the height of the groove.

			Pillar files can be used for accurate finishing when turning round drill holes into square slots, as their safe edges allow the DIYer to file close to the corner of the square and only remove material from one side. For a step by step guide, see: How to square a round hole with files

			Size Pillar files are available in narrower widths, which are labelled as demi-narrow or semi-narrow, narrow and extra narrow respectively.

			The narrower the file, the smaller the space it will fit into.

			Size Pillar files are usually available in lengths from 100mm (4 inches) to 300mm (12 inches).

			Equalling files are often smaller, normally ranging from 125mm (5 inches) to 197mm (7³/₄ inches).

			Square edge joint files are usually 150mm (6 inches) long.

			Swiss or American? Pillar files can be either Swiss or American pattern.

			Equalling files and square edge joint files are Swiss pattern files.