204 Agricultural Mechanics and Technology Systems
Copyright Goodheart-Willcox Co., Inc.
Blades are available for cutting wood, metals, and
other building materials. Reciprocating saw blades can
be purchased in lengths from 3”-12”. When selecting a
blade, you need to choose one that will easily stay fully
engaged beyond the depth of the work material, as
shown in Figure 8-34. A blade that is too short can
snag and cause the saw to push away from the
cut. Excessive blade length can make contact with
undesired objects on the opposite side of the cut. The
unsupported end of the blade will also have a tendency
to fl ex or wobble.
Blades for reciprocating saws can be made out
of high-carbon steel (the least expensive and most
common), high-speed steel (required for harder
materials), or a bimetal bond of carbon steel and HSS.
Bimetal blades combine the toughness of carbon steel
with the hardness of HSS, resulting in a blade that,
although more expensive, outperforms plain carbon
steel blades and lasts approximately 10 times longer.
Tool manufacturers use different mechanisms to convert the rotary
motion output of an electric motor to the linear motion of the reciprocating
blade. Regardless of the mechanism used, the result in a handheld tool
is the potential for strong vibration that must be kept under control.
Some reciprocating saws are equipped with a variable-speed option. The
higher speeds are for cutting soft wood, and slower speeds should be
used when cutting harder, denser materials. To maintain control when
using a reciprocating saw, keep the foot of the saw
in fi rm contact with the surface of the work. Failure
to maintain foot contact with the material results
in the blade catching in the kerf, which causes the
reciprocating motion to be transferred back to the user.
Jig Saws
Jig saws are moderately powered handheld
saws that use a reciprocating blade action similar to
reciprocating saws. See Figure 8-35. The base of a jig
saw is bigger than the foot of a reciprocating saw, and
jig saws use smaller, more delicate blades. Jig saws
are used to make precise, often curved cuts in wood,
metal, plastics, and other building materials. Many jig
saws are equipped with adjustments that allow the
base to be tilted for bevel cuts. Some have variable-
speed motors to allow for better quality cutting in a
large variety of materials. Jig saws may be powered by
standard 120-volt AC current, or they may be cordless
versions powered by rechargeable batteries.
Goodheart-Willcox Publisher
Figure 8-34. When using any reciprocating saw,
you should always ensure that the blade is long
enough to extend fully through the stock in both the
extended and the retracted position. A blade that
is too short can bind and violently force the saw
backward.
gresei/Shutterstock.com
Figure 8-35. The size and design of a jig saw allow
it to be used in many situations and for multiple
types of cuts.