Use the files as instructed and clean them often.
3. Never use a file without a securely attached handle unless it is
of the Swiss pattern type.
Do not use files for a purpose other than for which they were
5. Do not use oil since this will cause the file to slide across the
work preventing fast cutting.
6. Never strike the file against a vise or other object to remove
Use the file cleaner brush.
7. Never store files with lubricants or rust-preventive compounds on
them. Wrap each file in a waterproofed barrier wrapping paper and place the files
in racks or boxes so that the faces or edges of the files will not touch each
other. Keep files dry.
c. Hacksaws. These are saws used for cutting metal, much the same as a
carpenter's saw cuts wood. Common hand hacksaws have either adjustable frames or
solid frames. Hacksaw blades of various types are inserted in these frames, for
different kinds of work. Adjustable frames can be changed to hold blades from 8 to
16 inches long; solid frames, although more rigid, will take only the length blade
for which they are made. This length is the distance between the two pins which
hold the blade in place. All hacksaw frames hold the blades either parallel or at
right angles to them and are provided with screws for pulling the blades tight.
(1) Hacksaw blades. Hacksaw blades are made of high-grade tool steel,
hardened and tempered. There are two types: all-hard and flexible. AU-hard blades
are hardened throughout, while only the teeth of the flexible blades are hardened.
All blades are from 7/16 to 9/16 inch wide, have from 14 to 32 teeth per inch, and
are from 8 to 18 inches long. Each blade has a hole at each end which hooks to
pins in the frame.
(2) Set. The teeth of all hacksaw blades are set to provide clearance for
the blade; the three different kinds of set are alternate set, raker set, and
undulated set. Alternate set means that alternate teeth are bent slightly sidewise
in opposite directions; on a raker set blade, every third tooth remains straight
and the other two are set alternately; on an undulated set blade, short sections of
teeth are bent in opposite directions. A blade should be set just enough to give a
free, smooth, rapid cut in a slot just wider than the blade itself, removing no
more stock than is necessary.
(3) Selecting hacksaw blades. Selecting the best hacksaw blade for a
specific job is a question of using either an all-hard or flexible blade having a
pitch (number of teeth per inch) best suited to the work in hand.
(a) An all-hard blade is best for sawing brass, tool steel, cast iron,
rails, and other stock of heavy cross section.
(b) In general, a flexible blade is best for sawing hollow shapes and
metals of light cross section, such as channel iron, tubing, tin, copper, aluminum,
(c) Use a blade with 14 teeth per inch on machine steel.
pitch makes the saw free and fast cutting.