(f) When filing brass or bronze, start with a bastard cut file and
finish with a second or smooth cut file.
(g) When filing aluminum, lead, or babbitt metal, use a bastard cut
curved tooth file.
(h) For small work use a short file; for medium sized work use an 8-inch
file; for large work use a file that is most convenient.
(6) Method of filing.
(a) Clamp the work securely in a vise so that the area to be filed is
horizontal and is parallel to, and projecting slightly above, the vise jaws.
(b) Hold the file handle in one hand, thumb on top, and hold the tip of
the file with the fingers of the other hand.
(c) Apply
pressure on the forward stroke only. Unless the file is
lifted from the work
on the return stroke, it will become dull much sooner than it
should. When filing
soft metals, pressure on the return stroke helps keep the cuts
in the file clean of
waste metal.
{d) Use a rocking motion when filing round surfaces.
(e) When using a new file, do not apply too much pressure since the
teeth will break off - do not force the file. File slowly, lightly, and steadily.
Too much speed and too much pressure cause the file to rock and will round off the
corners of the work.
(f) Draw filing is used to produce a very smooth and true surface. To
draw file, hold the file at right angles to the direction of the strokes, with your
hands close together to prevent bending or breaking the file. Pressure should not
be great and can remain the same on the back stroke, as well as on the draw stroke.
The speed of filing is not important. For extra smooth surfaces, wrap a piece of
emery cloth around the file and stroke in the same manner.
(7) Care and safety precautions.
(a) Breaking in. A
new file should be broken in by using it first on
brass or bronze. Never use it
first to remove the fins or scales on cast iron. Do
not use a new file on a narrow
surface, such as sheet metal, because the narrow
edge of the metal is likely to
break off the sharp points on the file teeth.
(b) Cleaning. After using a new file, the teeth will clog up with metal
filings. Using a clogged file will scratch the work - this condition is called
pinning. One way to help prevent pinning is by rubbing chalk between the teeth
before filing. However, the best method to keep the file clean is to use a file
scorer and file cleaner brush. A scorer is a small pointed metal instrument, often
furnished with the file cleaner brush, and is used for cleaning out individual
teeth and grooves in the file clogged too tightly with metal to clean with the
brush. When cleaning a file with a file scorer, use a pulling motion, holding the
file scorer blade parallel to the rows of teeth. Finish cleaning by brushing the
file parallel to the rows of teeth with the file cleaner brush.
(c) Safety precautions.
1. Do not throw files in a drawer or tool box where they can rub
against each other or against other tools. Store them in separate holders, such as
clips, straps, or in holes cut in a block of wood.
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