Chapter 21 Processes Used to Separate Wood Materials 319
sharp radii and fancy designs of the outside edges of
the material being cut. However, this type of work
can be accomplished with other machines. Cutting
irregular curves inside of the stock is an operation
unique to this machine. When many ornate shapes
need to be cut, scroll sawing is often an ideal choice.
Blades used for scroll sawing are sized in terms
of the number of teeth per inch. The finer-toothed
blades (those with more teeth per inch) can be
used to cut sharper curves. Harder material such
as aluminum, copper, and plastics can also be cut
with scroll saws, but fine-toothed blades and slower
speeds are necessary. The blades are about 6″ to 8″
(15 cm to 20 cm) long, and are held in a vertical posi-
tion with spring tension between upper and lower
chucks. It is the up-and-down movement of the
lower chuck that moves the blade.
The scroll saw can also be used to produce
angled, rather than vertical, cuts. This is accom-
plished by tilting the table supporting the stock.
Typically, tables will tilt up to 15° to the left or 45° to
the right.
The scroll saw is ideal for making inside cuts.
These cuts can be accomplished without producing
an undesired saw cut across the pattern to get to the
inside. To do so, drill a relief hole, slightly larger than
the width of the blade, in an area where stock will
be removed. Then, loosen the blade from the upper
chuck of the saw. Move the lower chuck down by
rolling the motor pulley by hand. The stock can then
be placed on the saw table with the blade projecting
through the drilled hole. Fasten the blade in the
upper chuck again, and proceed with the inside cut.
While the scroll saw is fine for making small-
radius turns and cutting intricate designs, sharp
turns must be made slowly or the blade will break.
One disadvantage of the scroll saw is that it is not
very useful for cutting long straight lines. Because
of the very thin blade, it is difficult to cut long lines
which are perfectly straight and do not waver from
one side to the other.
Bandsaws
The bandsaw is used primarily for cutting
curved edges. The blade used in a bandsaw is a
band (continuous loop) with teeth cut into its edge.
The blade is held vertically in tension between two
rotating wheels. See Figure 21-16. The blade will last
a long time without needing to be replaced if it is
operated at a speed appropriate for the material being
cut. If the blade breaks, the ends of the broken blade
can be rejoined by welding. In some cases, a butt
welding fixture is attached directly to the bandsaw.
Bandsaws are sized by the diameter of the
wheels. The smallest machines are normally 10″,
while others have wheels as large as seven or eight
feet in diameter. These very large saws are used in
sawmills to cut logs into timber.
Angled cuts can be made by changing the angle
of the table. Straight cuts are made using a fence for
accuracy. On long straight cuts, however, the blade
sometimes will pull slightly to the left or right. This is
referred to as lead, and is usually caused by improper
tracking of the blade on the wheels. Since it is difficult
to avoid this problem, many operators prefer making
long cuts using a circular saw. The bandsaw works
best for cutting angles and large curves.
It is important to remember that the capability
of every saw is limited by the shape and width of
its blade. In bandsawing, the blade used is normally
from 3/8″ (9.5 mm) up to several inches in width. A
circle with a 2″ (5 cm) diameter can easily be cut with
a 3/8″ (9.5 mm) blade. However, if you try to cut a 1/4″
(6.3 mm) radius, the blade will not be able to turn this
sharply. It will bind and may break. In order to cut
such a sharp radius, the cut either must be broken up
into a series of tangential cuts that gradually work
toward accomplishing the sharp radius desired, or a
narrower width blade must be selected.
Figure 21-16. A bandsaw is useful for cutting circles and
arcs with a fairly large radius. The continuous-loop saw
blade is carried on large wheels inside the rounded safety
covers at the top and bottom of the machine.
(Delta International Machinery Corp.)
sharp radii and fancy designs of the outside edges of
the material being cut. However, this type of work
can be accomplished with other machines. Cutting
irregular curves inside of the stock is an operation
unique to this machine. When many ornate shapes
need to be cut, scroll sawing is often an ideal choice.
Blades used for scroll sawing are sized in terms
of the number of teeth per inch. The finer-toothed
blades (those with more teeth per inch) can be
used to cut sharper curves. Harder material such
as aluminum, copper, and plastics can also be cut
with scroll saws, but fine-toothed blades and slower
speeds are necessary. The blades are about 6″ to 8″
(15 cm to 20 cm) long, and are held in a vertical posi-
tion with spring tension between upper and lower
chucks. It is the up-and-down movement of the
lower chuck that moves the blade.
The scroll saw can also be used to produce
angled, rather than vertical, cuts. This is accom-
plished by tilting the table supporting the stock.
Typically, tables will tilt up to 15° to the left or 45° to
the right.
The scroll saw is ideal for making inside cuts.
These cuts can be accomplished without producing
an undesired saw cut across the pattern to get to the
inside. To do so, drill a relief hole, slightly larger than
the width of the blade, in an area where stock will
be removed. Then, loosen the blade from the upper
chuck of the saw. Move the lower chuck down by
rolling the motor pulley by hand. The stock can then
be placed on the saw table with the blade projecting
through the drilled hole. Fasten the blade in the
upper chuck again, and proceed with the inside cut.
While the scroll saw is fine for making small-
radius turns and cutting intricate designs, sharp
turns must be made slowly or the blade will break.
One disadvantage of the scroll saw is that it is not
very useful for cutting long straight lines. Because
of the very thin blade, it is difficult to cut long lines
which are perfectly straight and do not waver from
one side to the other.
Bandsaws
The bandsaw is used primarily for cutting
curved edges. The blade used in a bandsaw is a
band (continuous loop) with teeth cut into its edge.
The blade is held vertically in tension between two
rotating wheels. See Figure 21-16. The blade will last
a long time without needing to be replaced if it is
operated at a speed appropriate for the material being
cut. If the blade breaks, the ends of the broken blade
can be rejoined by welding. In some cases, a butt
welding fixture is attached directly to the bandsaw.
Bandsaws are sized by the diameter of the
wheels. The smallest machines are normally 10″,
while others have wheels as large as seven or eight
feet in diameter. These very large saws are used in
sawmills to cut logs into timber.
Angled cuts can be made by changing the angle
of the table. Straight cuts are made using a fence for
accuracy. On long straight cuts, however, the blade
sometimes will pull slightly to the left or right. This is
referred to as lead, and is usually caused by improper
tracking of the blade on the wheels. Since it is difficult
to avoid this problem, many operators prefer making
long cuts using a circular saw. The bandsaw works
best for cutting angles and large curves.
It is important to remember that the capability
of every saw is limited by the shape and width of
its blade. In bandsawing, the blade used is normally
from 3/8″ (9.5 mm) up to several inches in width. A
circle with a 2″ (5 cm) diameter can easily be cut with
a 3/8″ (9.5 mm) blade. However, if you try to cut a 1/4″
(6.3 mm) radius, the blade will not be able to turn this
sharply. It will bind and may break. In order to cut
such a sharp radius, the cut either must be broken up
into a series of tangential cuts that gradually work
toward accomplishing the sharp radius desired, or a
narrower width blade must be selected.
Figure 21-16. A bandsaw is useful for cutting circles and
arcs with a fairly large radius. The continuous-loop saw
blade is carried on large wheels inside the rounded safety
covers at the top and bottom of the machine.
(Delta International Machinery Corp.)