SQUARE files are tapered on all four sides and
are used to enlarge rectangular-shaped holes and slots.
ROUND files serve the same purpose for round
openings. Small round files are often called rattail
The HALF ROUND file is a general-purpose tool.
The rounded side is used for curved surfaces, and the
flat face on flat surfaces. When you file an inside
curve, use a round or half-round file whose curve
most nearly matches the curve of the work.
Kits of small files, often called swiss pattern or
jewelers files, are used to fit parts of delicate
mechanisms and for filing work on instruments.
Handle these small files carefully because they break
Using a file is an operation that is nearly
indispensable when working with metal. You may be
crossfiling, drawfiling, using a file card, or even
polishing metal. Lets examine these operations.
When you have finished using a file, it may be
necessary to use an abrasive cloth or paper to finish
the product. Whether this is necessary depends on
how fine a finish you want on the work.
CROSSFILING. Figure 1-30, view A, shows a
piece of mild steel being crossfiled. This means that
the tile is being moved across the surface of the work
in approximately a crosswise direction.
results, keep your feet spread apart to steady yourself
as you file with slow, full-length, steady strokes. The
file cuts as you push it ease up on the return stroke to
keep from dulling the teeth. Keep your file clean.
View B shows the alternate positions of the file
when an exceptionally flat surface is required. Using
either position first, file across the entire length of the
stock. Then, using the other position, file across the
entire length of the stock again. Because the teeth of
the file pass over the surface of the stock from two
directions, the high spots and low spots will readily be
visible after filing in both positions. Continue filing
first in one position or direction and then the other
until the surface has been filed flat. Test the flatness
with a straightedge or with prussian blue and a surface
DRAWFILING. Drawfiling produces a finer
surface finish and usually a flatter surface than
crossfiling. Small parts, as shown in view C, are best
held in a vise. Hold the file as shown in the figure;
notice that the arrow indicates that the cutting stroke
is away from you when the handle of the file is held
in the right hand.
If the handle is held in the left
hand, the cutting stroke will be toward you. Lift the
file away from the surface of the work on the return
stroke. When drawfiling will no longer improve the
surface texture, wrap a piece of abrasive cloth around
the file and polish the surface as shown in figure 1-31,
USE OF FILE CARD. As you file, the teeth of
the file may clog up with some of the metal filings
and scratch your work. This condition is known as
PINNING. You can prevent pinning by keeping the
file teeth clean. Rubbing chalk between the teeth will
help prevent pinning, too, but the best method is to
clean the file frequently with a FILE CARD or brush.
A file card (fig. 1-32) has fine wire bristles. Brush
with a pulling motion, holding the card parallel to the
rows of teeth.
Always keep the file clean, whether youre filing
mild steel or other metals. Use chalk liberally when
filing nonferrous metals.
FILING ROUND-METAL STOCK. Figure
1-30, view D, shows that as a file is passed over the
surface of round work, its angle with the work is
changed. This results in a rocking motion of the file
as it passes over the work.
This rocking motion
permits all the teeth on the tile to make contact and
cut as they pass over the works surface, thus tending
to keep the file much cleaner and thereby doing better
P O L I S H I N G A F L A T - M E T A L
SURFACE. When polishing a flat metal surface, first
draw tile the surface as shown in figure 1-30, view C.
Then, when the best possible drawfiled surface has
been obtained, proceed with abrasive cloth, often
called emery cloth. Select a grade of cloth suited to
the drawfiling. If the drawfiling was well done, only
a tine cloth will be needed to do the polishing.
If your cloth is in a roll and if the job you are
polishing is the size that would be held in a vise, tear
off a 6- or 8-inch length of the 1- or 2-inch width. If