Three Square File, Cut 2

Excel three square file, Cut 2

A file with a triangular section, that is with three working faces and three sharp edges. The cut carries the marking Cut 2, where a lower number means coarser teeth and a higher one finer teeth. It is one of the profiles reached for most often, because it covers two different situations at once.

Inner corners

A triangle sits into the corner where two surfaces meet at roughly a right angle and cleans it right down to the bottom, without working on both walls equally. That is where residue of glue, a flash of plastic or dried putty tends to sit, which abrasive paper cannot get out of a corner.

After nipping off the sprue

The second typical job is cleaning up a sprue nub. Nippers, even good ones, leave a stub on a part and slightly displaced material around it. A three square file knocks the stub down and its edge reaches right to the edge of the part, so it leaves no hollow of the kind a flat file braced against the surroundings makes. It is particularly useful on parts where the sprue meets an edge or a curve.

Use

• Nip the part off a little away from its edge and clean the stub up only once it is off the sprue, so the part does not break.
• Lead the file into a corner edge first and work in short strokes away from you.
• Do not press, as an edge removes material in a concentrated way and easily goes deeper than you want.
• Move on to abrasive paper after the file, as paint will not hide the mark of the teeth.
• Clean the teeth with a brush as you go, not only once the tool has stopped biting.

Who it is for

For anyone who builds plastic kits, that is for work that begins with nipping a part off the sprue and cleaning up its edge. Among individual files it belongs to the basic three alongside the flat and the round profile.

The file has sharp edges and sharp teeth, so protect your fingers. Do not inhale the dust and work in a ventilated room.