A piece of high-grade crucible steel, forged to
shape, ground, cut and carefully tempered, forms that tool so
indispensable to the mechanic - the file.
The file maker is no longer compelled to forge
his blanks from stock of unsuitable proportion, but receives
from the steel manufacturers stock of the required cross-section
to make all standard shapes. This reduces the forging to a
minimum, it being only necessary to cut the stock to the
required lengths, to draw down the point and form the tang. The
latter operation being very rapidly performed under power
The National Association of File Manufacturers prescribe to the
steel makers the forms of cross-sections they require.
Consequently, all makers of file steel can
furnish any section correct to gauge. In Fig. 13 are shown the
correct cross-sections of file steel for all the shapes in
general use. Each section is for an 8-inch file, full scale.
names of the files made from steel of these sections are,
referring to the numbers of the figure: I, “Hand” ; 2, “Flat”;
3, “Mill”; 4, “Pillar”; 5, “Warding”; 6, “Square”; 7, “Round”;
8, “Half-round”; 9, “Three-square”; 10, “Knife”; 11, “Pit-saw”;
12, “Crossing”; 13, “Tumbler”; 14 Cross-cut”; 15, “Feather-edge”;
16, “Cant-saw”; 17, “Cant-file”; 18, “Cabinet”; 19, “Shoe-rasp”;
It will be noticed that many of these files are
named from the form of their cross-section, and that those so
named are the ones most used for general work; while the others
receive their names from the special character of the work they
are expected to be used upon.
It will also be noted that the
stock for files of rectangular cross-section may be classified
as to thickness as follows: “Square,” the thickest; “Pillar,”
“Hand,” “Flat,” “Rasp and “Warding.” As to width, “Hand” is the
widest; “Flat,” “Rasp”,” “Mill” and “Warding” are the same
width; “Pillar” materially narrower, and “Square” the narrowest.
The “Half-round” is not a full semi-circle, the
arc being about one-third of the full circle. On the other hand,
the “Pit-saw” is a full half circle in section.
The “Three-square,” “Cant-saw” and differ in section in their
angles, the former having equal angles, 60 degrees, and equal
sides, the next 35-35 and 110-degree angles, and the latter
30-30 and 120-degree angles.
The length of a file is measured from point to
heal, and does not include the tang. The tang is usually made
spike shaped to receive a plain ferrule handle. Some makers
modify the form of tang to fit patented handles.
As forges, the blank for a “Hand” file, Fig. 15,
is parallel in thickness from heel to middle and tapered from
middle to point, making the point about one-half the thickness
of the stock. The edges of the blank are usually left parallel.
They are, however, sometimes drawn in slightly at the point.
The “Flat” file blank, Fig.16, is parallel in
both of its longitudinal section from heel to middle and tapered
in both sections from middle to point, the thickness of point
being about two-thirds and width about one-half that of the
For the “Mill” file the blank is parallel in
thickness from heel to point, and usually tapered to about
three-fourths the width of the stock. The “Mill” file is often
made blunt-that is, of equal width and thickness throughout its
The blank for the “Warding” file is tapered in
width from heel to point and is of uniform thickness. Aside from
width, the “Pillar” file is similar to the “Hand” file. The
“Pillar” file is also made is “narrow” and extra narrow
patterns, the extra narrow approximating a square in section.
The “Three-square,” “Square” and “Round” are
also made in slim and blunt forms. The “Slim” is a file of
regular length, but smaller cross-section, and the “Blunt” of
equal cross-section from heel to point, being either “slim” or
After forging, the blanks are thoroughly
annealed in annealing furnaces, the operation taking from
twenty-four to thirty-six hours. When the blank comes from the
furnace, it is twisted and scaly, and must be subjected to a
“straightening” process, after which the scale is removed by
“grinding” on very heavy grind-stones. The blanks are next
draw-filed to make them perfectly smooth and even, after which
they are ready for the cutting.