Metal Cutting Tools
Prepared by: Mr. Cael
Hand Snips
There are several kinds of hand snips, each of which
serves a different purpose.
Straight, curved, hawksbill, and aviation snips are in
common use.
Straight snips are used for cutting straight lines when the
distance is not great enough to use a squaring shear
and for cutting the outside of a curve.
The other types are used for cutting the inside of curves
or radii. Snips should never be used to cut heavy sheet
metal.
Tinner’s Snip
The tinner's snips or tin
snips are found in almost
every sheet metal shop.
These snips range in length
from about seven inches
up to 12 inches and, even
though they are basically
used for making straight
cuts, they are also used to
cut curves to either the left
or right.
Aviation Snip
In addition to being color-coded,
aviation snips can be identified by
their shape.
For example, a straight snip has a
relatively straight nose. However,
with right-cut snips, when held in
your hand, the lower jaw is on the
right whereas the lower jaw is on
the left with left-cut snips.
Aviation snips are designed especially for cutting heat
treated aluminum alloy and stainless steel.
They are also adaptable for enlarging small holes. The blades
have small teeth on the cutting edges and are shaped for
cutting very small circles and irregular outlines.
The handles are the compound leverage type, making it
possible to cut material as thick as 0.051 inch.
Aviation snips are available in two types, those which cut
from right to left and those which cut from left to right.
Unlike the hacksaw, snips do not remove any material when
the cut is made, but minute fractures often occur along the
cut. Therefore, cuts should be made about 1⁄32 inch from the
layout line and finished by hand filing down to the line.
Hacksaws
The common hacksaw has a blade, a frame, and a
handle. The handle can be obtained in two styles: pistol
grip and straight.
Hacksaw blades have holes in both ends; they are
mounted on pins attached to the frame.
When installing a blade in a hacksaw frame, mount the
blade with the teeth pointing forward, away from the
handle.
Hacksaws
Blades are made of high-grade tool steel or tungsten steel
and are available in sizes from 6 to 16 inches in length.
The 10-inch blade is most commonly used. There are two
types, the all-hard blade and the flexible blade. In flexible
blades, only the teeth are hardened.
Selection of the best blade for the job involves finding the
right type and pitch. An all-hard blade is best for sawing
brass, tool steel, cast iron, and heavy cross-section materials.
A flexible blade is usually best for sawing hollow shapes and
metals having a thin cross section.
Hacksaws
The pitch of a blade indicates the number of teeth per
inch. Pitches of 14, 18, 24, and 32 teeth per inch are
available.
A blade with 14 teeth per inch is preferred when cutting
machine steel, cold rolled steel, or structural steel.
A blade with 18 teeth per inch is preferred for solid stock
aluminum, bearing metal, tool steel, and cast iron.
Use a blade with 24 teeth per inch when cutting thick-
walled tubing, pipe, brass, copper, channel, and angle
iron.
Use the 32 teeth per inch blade for cutting thin-walled
tubing and sheet metal.
When using a hacksaw, observe the
following procedures:
1. Select an appropriate saw blade for the job.
2. Assemble the blade in the frame so that the cutting edge of the
teeth points away from the handle.
3. Adjust tension of the blade in the frame to prevent the saw from
buckling and drifting.
4. Clamp the work in the vise in such a way that will provide as
much bearing surface as possible and will engage the greatest
number of teeth.
5. Indicate the starting point by nicking the surface with the edge of
a file to break any sharp corner that might strip the teeth. This mark
will also aid in starting the saw at the proper place.
6. Hold the saw at an angle that will keep at least two
teeth in contact with the work at all times. Start the cut
with a light, steady, forward stroke just outside the
cutting line. At the end of the stroke, relieve the pressure
and draw the blade back. (The cut is made on the
forward stroke.)
7. After the first few strokes, make each stroke as long as
the hacksaw frame will allow. This will prevent the blade
from overheating. Apply just enough pressure on the
forward stroke to cause each tooth to remove a small
amount of metal. The strokes should be long and steady
with a speed not more than 40 to 50 strokes per minute.
8. After completing the cut, remove chips from the
blade, loosen tension on the blade, and return the
hacksaw to its proper place.
Thank You!
