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A 7-1/4 inch Circular saw consists of a metal
disc having a sharp serrated edge, mounted firmly onto a metal casing,
with a motor to provide the rotating power. This saw may be either
handheld or fixed on the edge of a table. While these saws are most
commonly used to cut wood, they can also incorporate blades that permit
them to slice through hardened plastic, masonry, and even metal. The
saw is a heavy duty implement that can have applications ranging from
simple metal fabrication tasks to building wood or metal reinforced
houses. It is a multi-functional tool used for cleaning and slotting a
variety of materials, in addition to its conventional job of cutting.
Since a circular saw does not have a built-in cutting guide and only
has a handheld guide without a Fence and table system, it is mostly
used for rough cutting. This tool is one of the easiest gadgets to cut
through materials ranging from plywood to other harder materials. Since
its invention in the 1700’s, the circular saw has now become a
mandatory implement for carpenters, building contractors, masons, and
other workmen. In addition to skilled professionals, this tool can be
used by the do-it-yourself enthusiasts too and is often seen in the
tool kit of many households.
Features and working of the 7 – 1/4 inch circular saw
Circular saw disc diameters range from around
3 – 3/8 to 16 – 5/8 inch, with the 7–¼ inch blade being the most
popular. The type of the blade used depends on the size and shape of
the arbor or spindle. Most circular saws have a blade guard that
ensures that the blade only cuts the material it is meant to slice
into. This blade guard can be raised manually if needed. A tilting base
enables the user to change the cutting angle. For smooth operation,
this base can get firmly locked into the angle chosen by the user. A
spindle lock button makes changing blades a simple and quick
proposition. Generally, more the teeth in a blade, sharper the cut.
This tool is powered by either electricity or
a battery. While the electricity driven circular saws require the tool
to be connected to a power outlet near the work area, battery powered
saws use Rechargeable batteries. Commonly used 7–1/4 inch circular saws
are powered by around a 2 to 4 horsepower motor using around 15 amps to
generate a no-load velocity of approximately 5000 revolutions per
minute (rpm). The overall weight of the saw varies between around 10 to
14 pounds.
Depending on construction, circular saws are
broadly of two types; sidewinder and worm drive. In a sidewinder
circular saw, the motor is mounted at the side of the blade, whereas in
the worm drive type, the motor is inline with the blade. While being
more expensive, the worm drive type of saw, offers more power. Worm
drive gears are often precision- machined for maximum power utilization
and increase durability of the tool. The life of the tool is further
enhanced through use of die cast aluminum motor and gear compartments
as well as the presence of an oil indicator Level and relief bellows.
Additionally, dependent on which side of the blade the motor is
mounted, circular saws are also classified as either left-handed or
right handed. User-friendly depth and bevel adjustments, going as far
as 50 degrees makes for smooth and precise operation. The body of the
circular saw should be of a sturdy, but at the same time lightweight
material. This will make the saw more manageable and reduce user
fatigue.
Some saws have a twin beam laser guiding
system which charts out a cutting path between the two light beams,
simplifying the task for the user of channeling through the material. A
rear view depth adjustment feature enables the user to view and then
modify, if necessary, the cut depth. An anti-snag lower guard feature
minimizes the occurrences of snags during cutting.
What to look for in a 7–1/4 inch circular saw
While cordless saws are more portable, the
user will need to frequently charge the batteries, which may get
discharged after prolonged use. While using a 24-volt battery, these
saws may not be able to generate as much torque as corded saws.
The tool handles should be ergonomically
arranged, with a sturdy construction and soft padded covers to provide
a good grip for the user. Depending on the intended use the horsepower
and the rpm requirements may vary, the value of these parameters going
up for high intensity tasks. It is a known fact that a low powered saw
used for demanding jobs can result in over heating of the blade,
causing blade wear out and even a kickback effect, which can prove to
be dangerous for the user. An important protective feature is the
safety lock for the trigger, which will prevent the tool from
accidentally starting.
Some reputed manufacturers of circular blades
include Bosch, Dewalt, Makita, and Milwaukee.
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