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Tip
#55
Table Saw Basic Cuts
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Saw
Blades
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Figure
2-3.
An all-purpose blade can be used for crosscutting, ripping,
and mitering. It is a good sizing blade,
but it will not cut as smoothly as some other special
blades.
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There
are several types of saw blades available for the table saw.
Each of them are ground and/or set to accomplish specific
wood-working operations. The following are the most common
blades and what they do:
All-Purpose
Blade--This blade (Figure
2-3) is the sawing work-horse of most woodworking shops.
The deep gullets between the teeth provide plenty of room
for waste removal on ripping operations and the sharp tooth
points do a reasonably good job when crosscutting. An all-purpose
blade enables you to start with basic operations like crosscutting,
ripping, and mitering, but it is not the only blade you can
use. You'll get better results on particular types of sawing
when you use a blade that was specially designed for the work
you are doing.
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Figure
2-4.
A crosscut blade has many small teeth that cleanly cut
wood fibers. The blade does a fair job on miter cuts
and sawing plywood. It should never be used for ripping.
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Crosscut
Blade--A crosscut blade has many small teeth ground with
alternating top bevels, sharp points and shallow gullets (Figure
2-4). The teeth cut cleanly across wood fibers, and since
the waste that is produced is a fine sawdust, the blade functions
efficiently with shallow gullets. However, small teeth and
shallow gullets can cause the blade to choke if
you try to force the cut. Here, even more than with other
blade designs, feed pressure should be slow and steady--only
enough so the teeth will cut as they were designed to cut.
The crosscut
blade does a respectable job on miter cuts, may be used on
plywood, but should never be used for ripping.
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Figure
2-5.
Each tooth of the ripping blade works like a tiny chisel
to chip out its own bit of wood. Deep gullets collect
and spew out the heavy waste. This blade should never
be used for general-purpose sawing.
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Ripping
Blade--A ripping blade (Figure
2-5) has large teeth ground with a square chisel tooth,
large gullets and is designed for sawing with the grain of
the wood. There is considerable support metal to back up the
cutting edges, and generous gullets catch and disperse the
sawdust.
Because
it has a special design, the ripping blade should never be
used for general sawing.
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Figure
2-6.
A hollow-ground blade does not have set teeth. Kerf
clearance is provided by gauge reduction from the tips
of the teeth to the center core that is indicated by
the arrow. The blade requires more projection than other
designs.
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Hollow-Ground
Blade--A hollow-ground blade (Figure
2-6), or planer blade as it is sometimes called,
produces a cut nearly as smooth as a planed edge. Most blades
have set teeth; that is, alternate teeth are bent a bit in
opposite directions This forms a kert that is wider than the
blade thickness so the blade has clearance in the cut. The
hollow-ground blade is reduced in thickness from the points
of its teeth to the full-gauge center area that is indicated
by the arrow in the photograph. Since this design, rather
than set teeth, gives it clearance in the cut, it produces
smoother cuts than other blades. The blade can function without
binding or burning itself or the wood by using it with the
correct projection.
In a strict
sense, it is a combination blade, but it is not one to leave
on the machine for general sizing cuts. It does fine on plywood,
but may not be tempered to stay sharp for an extended period
of time under the abrasive action of the plywood glue. Additional
uses for the hollow-ground blade include smooth crosscuts
or miter cuts, trimming moldings, and other advanced cutting
techniques.
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Figure
2-7.
A plywood blade has many small teeth and ve,y little
set. It is used for trimming and cutting plywood and
laminates, and for finish crosscuts in soft woods. It
produces a smooth and near splinter-free cut.
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Plywood
Blade--A plywood blade has many small teeth and very little
set (Figure 2-7).
This blade trims and cuts plywood and other laminates. Because
of the very small teeth, it produces a smooth cut and also
reduces splintering along the kerf. The plywood blade can
also be used for crosscutting soft woods, preferably finish
cuts only. General use will dull the teeth quickly, as will
certain types of plywood cores (particle and fibre). For cutting
particle or fibre core plywood and other sheet stock, it would
be better to use a carbide-tipped blade.
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Figure
2-8.
Carbide-tipped saw blades are smooth cutters used for
many operations and different materials: (A) combination,
(B) crosscut, and (C) rip.
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Carbide-Tipped
Blade--Carbide-tipped blades (Figure
2-8) are more expensive than conventional blades; but,
since they stay sharp for much longer periods of time, they
can prove to be more economical in the long run. They are
high-quality saw blades specially designed for splinter-free
results in hardwoods, softwoods, and materials like hardboard
and plywood, whether you are cross-cutting, ripping, or mitering.
Carbide
is a tough material, but it is also brittle. Be careful when
handling such blades; store them so they can't contact another
blade or object. Never use a car-bide blade to saw second-hand
lumber that could contain nails.
Cutting
Tips--With any table saw blade, remember that the teeth
above the table's surface rotate in the direction of the operator
and enter the top surface of the workpiece first; therefore,
place the wood with the finished side upward. This applies
to plain plywood, veneers, and any form of plywood with laminates
attached. When both sides of the wood are finished, use a
fine-tooth blade with minimum set or a hollow-ground blade.
Also keep in mind that the kerf is the slot formed by the
blade. Its width will differ depending on the style, the gauge,
and the amount of set on the teeth of the blade. The kerf
should always be on the waste side of the cutline.
Saw
Blade Maintenance
Any saw blade will work more efficiently when it is clean
and free of deposits that sawing wood can leave. Don't remove
deposits by working with a sharp instrument like a knife.
Some woodworkers use a commercial pitch remover or work on
the tooth areas with a solvent and old toothbrush. An easy
method to try is simply to soak the entire blade in warm water
and detergent. Wipe the blade with a cloth while it is in
the soapy water, rinse, then thoroughly dry it. Apply a very
light film of paste wax and buff.
Sharp
blades are, of course, a must. They cut more efficiently and
are safer to use since the operator doesn't have to utilize
excessive force to feed the stock-a situation that could cause
hands to slip.
Some woodworkers
sharpen their own blades, but it isn't recommended. A less
than perfect job will do more harm than good and can even
ruin the blade. The cost of sharpening is small, and the professional's
experience and special equipment will ensure that the blade
will be returned in like-new condition.
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Figure
2-9.
A specialstorage case will protect your saw blades.
Add a handle and you'll have a tote for cariying blades.
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Storing
Blades
The simplest way to store blades is to place them on hooks
that are spaced so the blades won't touch each other. This,
however, requires much space. To minimize space requirements,
use a hook long enough to hold several blades, and use heavy
cardboard or some other soft material as spacers between the
blades.
A blade
storage case like the one shown in Figure
2-9 will hold six blades and, when fitted with a handle,
will serve as a tote for a full assortment of blades. Layers
of 1/4" plywood (Figure
2-10), some solid and some with a semi-circular cutout,
are laminated to make up the storage area.
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Figure
2-10.
Construction details of a saw blade storage case. You
can widen it for more blades by adding layers of plywood
to create more slots. Click on image for larger view.
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You can
provide for more blades by adding more plywood layers, but
you must adjust the dimensions of the hinged cover if you
do. To hold the blades steady and keep them from moving about,
cement a piece of thick foam rubber to the underside of the
cover's top piece.
Continue
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Techniques
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