How to use a file

Eye Protection

Always wear safety glasses or goggles – metal swarf (filings) can fly into your eyes, especially when filing harder metals.
Choose the Right File
Cut (coarseness): Use a bastard or second-cut file for fast removal of material. Use a smooth or dead-smooth file for finishing and fine work. Shape: Use a flat file for general surfaces, a half-    round for curves and concave surfaces, and a triangular or square file for corners and slots. Size: A longer file (e.g., 250–300 mm) is better for large, flat surfaces; a shorter file (e.g., 150–200  mm) gives more control on small workpieces.

Fit a Handle (Essential)

Always fit a sturdy wooden or plastic handle onto the file’s tang (the pointed end).
Never use a file without a handle – the tang can puncture your palm or wrist if the file jams.

Secure the Workpiece

Clamp your workpiece firmly in a vice with the jaws just above the vice surface.
Protect finished surfaces by using soft jaws (copper, aluminium, or leather) over the vice jaws.
Keep the work at elbow height so your forearm is roughly horizontal when filing.

Correct Grip

Hold the handle with your dominant hand, with your palm over the end of the handle and your thumb along the top.
Place your other hand on the front (toe) end of the file, with your fingers curled over the top edge and your thumb resting on the underside or side – this hand applies downward pressure and guides   the file.

The Filing Stroke (Forward Cut Only)

Files cut on the forward (push) stroke only.
Forward stroke: Apply firm, even downward pressure with both hands. Push the file smoothly and steadily forwards at a slight angle (about 10–15°) across the work to produce a shearing action.
Backward stroke: Lift the file slightly off the work on the return stroke – or at least release all downward pressure – to avoid blunting the teeth.
Use the full length of the file where possible, not just the middle.

Body Position and Motion

Stand with your feet shoulder-width apart, facing the vice.
Move your whole upper body from the shoulders, not just your arms – this gives a straighter, more controlled stroke.
Keep the file level throughout the stroke to avoid rounding the edges of your work.

Checking Your Progress

Pause frequently and clean the file teeth with a file card or a stiff wire brush (brass is best to avoid damaging the teeth).
Check your work with a straight edge or square to see where high spots remain.
Mark high spots with a marker pen or engineer’s blue, then file again until the surface is flat.
Draw-Filing for a Smooth Finish
For a finer finish, use draw-filing:
Hold the file in both hands, one at each end, perpendicular to the work.
Pull the file sideways (across the work) with light, even pressure, using the length of the file like a sanderThis removes scratches and leaves a smooth, polished surface.

Safe Use and Storage

Never strike a file with a hammer – they are hardened and brittle; they will shatter.
Never use a file as a pry bar or lever.
Clean your file after use with a file card, brushing in the direction of the teeth (from heel to toe) to remove swarf.
Store files separately so their teeth do not knock against each other – use a rack, a cloth roll, or wrap each in oily rag.
Lightly oil your files after cleaning to prevent rust.

Pro tip:

For soft metals like aluminium or brass, use a file with a coarser cut and clean it more frequently, as these metals clog teeth quickly. For hardened steel, you will need a new, sharp file – a blunt file will just skid and burnish.