An equalling file — also called a flat equalling file — is a parallel-sided hand file used by jewellers, bench workers, and goldsmiths to produce uniform slots, channels, and flat surfaces in metal. Unlike tapered flat files, which narrow progressively toward the tip, the equalling file maintains a consistent width along its entire working length, giving the craftsperson precise dimensional control when filing into confined spaces or when the width of the cut must remain constant from entry to exit.

Form and Specification

Equalling files are manufactured in widths typically ranging from approximately 2 mm to 8 mm, with lengths (excluding the tang) commonly falling between 100 mm and 200 mm. Both faces are flat and cut, and the edges may be safe (uncut) or lightly cut depending on the maker and intended application. The parallel profile is the defining characteristic: the file neither widens nor narrows, so the slot or channel it produces mirrors its own cross-section with a high degree of accuracy.

Like all hand files, equalling files are graded by cut — from coarse (bastard) through second-cut to smooth and needle-fine — allowing the bench worker to progress from rapid stock removal to refined finishing within the same tool geometry.

Applications in Jewellery Making

The equalling file is particularly valued wherever a component must slide, seat, or align within tight tolerances:

• Bezel and collet fitting: Opening or truing the interior of a bezel so that a stone or insert seats squarely without rocking.
• Hinge joints: Filing the knuckle slots of a box clasp or locket hinge to accept the hinge pin with minimal play.
• Channel settings: Refining the channel walls so that calibrated stones sit at a uniform depth and the metal walls are parallel.
• Slide and tongue mechanisms: Fitting the tongue of a box clasp or the slide of a bracelet fastener so that movement is smooth and the fit is snug.
• Flat surface preparation: Truing a flat face before soldering, ensuring full contact between components and reducing the risk of voids in the joint.

Distinction from Related Files

The equalling file is frequently confused with the ordinary flat file, but the two differ in a functionally important way: a standard flat file tapers slightly in both width and thickness toward the point, which causes the cut to widen or deepen unpredictably when working inside a slot. The equalling file's parallel sides eliminate this variable. It is similarly distinct from the needle file (which is much finer and intended for detail work at small scale) and from the warding file (which is thin and narrow but also tapered). The term parallel file is used interchangeably in some trade catalogues.

Material and Care

Equalling files intended for jewellery use are made from hardened high-carbon or alloy tool steel, with the cut teeth formed by chisel-tooth milling or hand-raising before hardening. They are used on non-ferrous metals (gold, silver, platinum, copper alloys) as well as on steel findings. As with all files, single-directional strokes — pushing the file forward on the cut stroke and lifting on the return — prolong tooth life. A file card or wire brush should be used regularly to clear the teeth of metal filings (pins), which, if allowed to accumulate, score the work surface.