Why you should have files and rasps in your toolbox

Published: October 4, 2019

close up of various files and rasps Photo by Liam Mogan

Files and rasps are easy-to-learn tools for abrading material. They’re hardened steel shaping bars, available in many shapes, with teeth ranging from coarse to super-fine. Start your collection with a flat mill bastard file (useful for sharpening), a handle, and a four-in-hand (a combination half-round rasp and coarse wood file).

Files can be rectangular or flat; half-round; round or rattail; or triangular. Choose depending on the surface being shaped. (For example, a half-round rasp or file face is better for concave surfaces.) With teeth cut in lines, they come in different levels of coarseness from “dead-smooth,”  to “smooth,” “second-cut,” “bastard,” and then “coarse.” Metal files are known as mill files. With a mill bastard file, you can sharpen axes and lawn mower blades before honing. And taming sharp edges on deck and dock boards is a breeze with a coarse wood file. Holding the handle and the distal tool end, make full-length strokes and lift on the return stroke. Keeping the tool in contact with the surface on the return will only dull the teeth. 

Rasps are coarser than files; they have individually raised points of metal that serve as shaping abraders—ever tangoed with a raspberry cane?! They come in a range of tooth sizes. Larger teeth remove more material per stroke and leave a rougher finish. Follow up with a file and/or sandpaper to achieve a smooth surface, as rasps will leave a deeply scratched finish.

When storing your rasps and files, don’t let files touch each other, as the hard steel is brittle, and the teeth can be damaged. To prevent them from rusting, I store my rasps and files with moisture-absorbing silica-gel packs I have saved. And you’ll want to invest in a file card—a specialty brush with metal or fibre bristles used to clean files and rasps. Brush parallel to the cutting teeth to remove embedded metal or wood and ensure a long working life.

Files
Used for soft and hard metals and wood.

Rasps
Used for wood or soft materials.

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