Fret Crowning File — Lutherie Encyclopedia

Fret Crowning FileType: toolA concave-edged file that reshapes flattened fret tops back into a rounded crown after leveling.## Description A fret crowning file has a concave cutting surface that matches the curved profile of a fret wire crown. When drawn along a leveled (flattened) fret, it removes material from the sides of the fret while preserving the center apex, restoring the rounded shape needed for clean string contact. Crowning files are available in different widths to match various fret wire sizes, from narrow vintage wire (0.080 inches) to jumbo wire (0.110 inches). They may be diamond-coated, traditional cut-tooth, or ceramic. ## Use in Lutherie After fret leveling, the tops of the frets are flat, which creates a wide contact surface with the strings and causes intonation problems and a mushy feel. Crowning restores the narrow, rounded apex that provides a precise contact point for each string. The file is guided along each fret, removing material symmetrically from both sides until only a thin line of the flat top remains, then finishing to a smooth, rounded profile. This is followed by sanding with progressively finer grits and polishing. ## Selection Guide Choose a crowning file that matches the width of your fret wire. Stew-Mac offers files in multiple sizes with a self-guiding concave profile that makes the process nearly foolproof. Diamond-coated files from Hosco and Gurian cut smoothly and last a long time. A medium-width file (for 0.090 to 0.100-inch wire) covers the most common fret sizes. Budget 20 to 60 dollars for a quality crowning file. ## Tips - Use marker ink on the fr…