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forward off the front of the wheels. Therefore,
be careful not to put too much pressure on the
stone. When doing this, it is also important that
the upper guides be positioned right above
the stone.
The blade has teeth and extreme caution
must be exercised, as your hands will
be very close to them.
Causes of blade breakage
1.
Excessive blade thickness in relation to the
flywheel diameter.
2.
Defective welding.
3.
Incorrect tension, particularly if the blade is
over tensioned; the tension spring no longer
fulfils its function.
4.
After use it is recommended that you slacken
the tension, especially overnight. (Be sure to
place a clearly visible note on the machine that
you have done this.
5.
Misalignment of the flywheels.
6.
Irregularity of flywheel surface, for instance,
an accumulation of sawdust while cutting
resinous materials.
You can correct these problems by readjusting
the machine, changing the way you operate it
or by changing the blade. Try only one change
at a time.
Causes of blade dulling.
1. Poorly set side guides or rear thrust guide.
2. Poor tracking.
3. Wrong blade selection. If the blade is too
narrow, it will flex more easily and decrease the
quality of the cut. The blade should also have
the correct pitch and width.
4. The tooth pitch is too fine (too many teeth
per inch).
5. Certain woods will dull a steel blade very
quickly, especially tropical hardwoods (teak,
koa, etc.). Other woods with a high silicon
content will also dull the blade quickly; even a
cut as short as 152,4mm will cause damage to
the blade.
6. On certain exotic woods, the ends have been
painted. This is done to control the drying.
The paint is very abrasive and will dull the
blade as you cut through it. It is recommended
that you cut the painted ends off your wood.
Using a radius chart.
Until you become well acquainted with your
saw, it is best to use the contour (radius) chart
to determine which size blade to use for a
specific application. Radius charts can be found
in many woodworking books, magazine articles
and on blade boxes. They differ slightly from
one another but are good as rough indicators of
how tightly a curve can be cut with a particular
blade. Each blade saw and operator is different,
so it is impossible to make a truly accurate
chart. A blade can cut continuously without
backtracking any curve that has a radius as
much as or more than is shown on the chart.
For example: a 3/16“ blade will cut a circle with
a 5/16“ radius or a 5/8“ diameter. To test if a
3/16“ blade would work for a particular curve,
place a dime (roughly 5/8“) over the pattern.
The 3/16“ blade can cut a curve bigger than the
dime, but not smaller. You can use everyday
items such as coins or a pencil to determine
which blade to use. A quarter is the size of the
tightest cut that can be made with a 1/4“ blade.
A dime is the size of the tightest curve that can
be cut with a 3/16“ blade. A pencil eraser is the
size of the tightest turn that you can make with
a 1/8“ blade. After a while you won‘t even need
an object to size the possible curve of a blade
because you will have become familiar with this
process. There are options to matching the
blade to the smallest curve pattern. If there is
only one very tight cut, it may be best to use a
turning hole, a relief cut, successive passes or
to change the blade. If you have a lot of cutting
to do, you can use a wider blade for the bigger
curves and then switch to a narrower blade for
the tighter curves. Changing the blades can
often save cutting and finish time. The chart
above is only a rough guide and is
not to scale
,
but from the information you can construct your
own guide.
8.3 How to coil a bandsaw blade
Without a doubt it is more difficult to explain
how to coil a bandsaw blade than it is to
actually do it. Nevertheless, below are easy-to-
follow instructions on folding a blade.
Method 1
While wearing a jacket or long-sleeved shirt and
gloves, hold the blade in front of you in one
large loop, with the teeth facing towards you.
Place your foot on the blade, holding it on the
ground. Grasp the blade with both hands, with
your thumbs to the outside, at approximately
the 10 o‘clock and 2 o‘clock positions (Step 1).
Slowly twist the top of the blade away from
your body (Step 2). Bring your hands together
to form two loops while folding down (Step 3).
Continue rotating the blade until you form three
loops.
Note
. It is recommended that the blade be
placed on material that will not damage the
blade teeth (wood or cardboard). Your foot
is there to give stability and not to clamp the
blade, so do not exert excessive force, or the
teeth/band may be damaged. The photographs
are shown without gloves to enable the hand/
thumb position to be shown. Gloves must be
worn, as the blade could cause injury.
Step 1
Step 2
Step 3
Done
Note: In order to show the hand/thumb position
of the man in the photographs, he is not
wearing gloves, but gloves MUST BE WORN as
the blade could cause injury.
Method 2
There is another variation of this that works well
with small blades but simply is not
possible for larger bandsaw blades, unless
you‘re very big and strong. This method works
the same as the method above, but rather than
holding the blade with both hands, grasp
the blade at the top while holding the bottom of
the blade with your foot (teeth still facing
away from you). Grasp the blade with your
hand, twisting your arm such that your elbow is
facing away from your body (Step 1). Turn the
palm of your hand toward your body about
180 degrees and then continue turning while
pushing down on the blade (Steps 2, 3 and 4).
The blade will fold down upon itself into three
circles, lying flat on the ground (Done).
Blade width
Cutting Rad
