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Saw Blades 101
It pays to be choosy when you shop for saw blades -
making smooth, safe cuts with your table saw, radial arm
saw, chop saw, or sliding compound miter saw depends on
having the right blade for the tool and the right blade for
the type of cut you want to make. There is no shortage of
saw blades on the market, and quality and performance varies
dramatically from blade to blade.
At Rockler Woodworking and Hardware, we
carry a complete line of saw blades, covering just about
every application you'll run into. And we take the guesswork
out of shopping for saw blades by carrying only blades made
by the finest manufacturers like Freud and Forrest (to name
just two). Now we want to make getting just the right saw
blades even easier -- so we put together this article, where
we'll bring you up to speed on important saw blade facts and
terminology and offer a little advice on picking out the
right blades for your woodworking operation.
How do I pick out the right saw blade?
Saw blades really aren't all that
complicated. To put together the perfect saw blade
collection, you just need to know a little about what
different types of saw blades do best, and about what
separates top-quality saw blades from the rest of the pack.
From there you'll be all set to choose the blades that best
suit your woodworking needs and budget. Whether you're
planning to build your own high-end kitchen from scratch, or
you just need to rip down a few feet of lumber, Rockler has
the blade or blades you'll need.
Saw Blade Essentials
Most saw blades are designed to do their best work in a
certain type of cutting operation. There are blades designed
for ripping lumber, crosscutting lumber, cutting veneered
plywood and panels, cutting laminates and plastics, cutting
melamine, and cutting non-ferrous metals. There are also
"general purpose" and "combination" blades, which are
designed to work well in two or more types of cut. What a
blade does best is determined by the number of teeth, the
type of gullet, the tooth configuration and the hook angle
(angle of the tooth).
Number of Teeth
In general, blades with more teeth yield a
smoother cut, and blades with fewer teeth move material
faster. A 10'' blade designed for ripping lumber, for
example, usually has as few as 24 teeth, and is designed
quickly move material along the length of the grain. A rip
blade isn't designed to yield a mirror-smooth cut, but a
good rip blade will move through hardwood with little effort
and leave a clean cut with a minimum of scoring.
A crosscut blade, on the other hand, is designed to give
you a smooth cut across the grain of the wood, without any
splintering or tearing of the material. A crosscut blade
will usually have from 60 to 80 teeth. Here, more teeth mean
that each tooth has to move less material. A crosscut blade
makes many more individual cuts as it moves through the
stock than a ripping blade. The result is a cleaner cut on
edges and a smoother cut surface. With a top-quality
crosscut blade, the cut surface will appear polished.
Gullet
The gullet is the space cut away from the
blade plate in front of each tooth to allow for chip
removal. In a ripping operation, the feed rate is faster
than in crosscutting and the chip size is bigger, so the
gullet needs to be deep enough to make room for the large
amount of material it has to handle. In a crosscutting blade
the chips are smaller and fewer per tooth, so the gullet is
much smaller. The gullets on some crosscutting blades are
purposely sized small to inhibit a too-fast feed rate, which
can be a problem, especially on radial arm and sliding miter
saws.
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The gullets of a combination blade are designed
to handle both ripping and crosscutting. The large
gullets between the groups of teeth help clear out
the larger amounts of material generated in ripping.
The smaller gullets between the grouped teeth
inhibit a too-fast feed rate in crosscutting.
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Tooth Configuration
The shape of the saw blade tooth and the way the teeth are
grouped also affect the way the blade cuts. The
configuration of the teeth on a saw blade has a lot to do
with whether the blade will work best for ripping,
crosscutting, or laminates.
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Flat Top (FT) Flat top teeth are
used on blades made for ripping hard and soft woods.
Since wood is much less likely to chip and splinter
when it is being cut in the direction of the grain,
the focus of a rip blade is to quickly and
efficiently remove material. The flat top tooth is
the most efficient design for cutting and raking
material out of the cut. |
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Alternate Top Bevel (ATB)
"Alternate top bevel" means that the saw blade teeth
alternate between a right and left hand bevel. This
tooth configuration gives a smoother cut when
crosscutting natural woods and veneered plywood. The
alternating beveled teeth form a knife-like edge on
either side of the blade and make a cleaner cut than
flat top teeth. |
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Combination Tooth (Comb.) The
combination (4&1) configuration is used for
"combination" blades -- blades designed to do both
crosscutting and ripping. The teeth are arranged in
groups of five - four ATB teeth and one FT -- with a
large gullet in between the groups. |
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Triple Chip Grind (TCG) The TCG
configuration excells at cutting hard materials like
laminates, MDF, and plastics. Teeth alternate
between a flat raking tooth and a higher "trapeze"
tooth. The TCG configuration is also used for
non-ferrous metal cutting blades. |
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High Alternate Top Bevel (HiATB)
The HiATB configuration is used for extra-fine
crosscutting and to cut materials surfaced with
melamine, which is prone to chipping. The high bevel
angle increases the knife-like action at the edge of
the blade. |
Hook Angle
On most saw blades, the tooth faces are tipped either toward
or away from the direction of rotation of the blade, rather
than being perfectly in line with the center of the blade.
Hook angle is the angle formed between the tooth face and a
line drawn from the center of the blade across the tip of
the tooth. On a blade with a positive hook angle, the teeth
are tipped toward the direction of the blade's rotation. A
negative hook angle means that teeth tip away from the
direction of rotation, and a zero degree hook angle means
that the teeth are in line with the center of the blade.
Hook angle affects blade operation in important ways. A
blade with high positive hook angle (+20 degrees is a high
hook angle) will have a very aggressive cut and a fast feed
rate. A low or negative hook angle will slow the feed rate
and will also inhibit the blade's tendency to "climb" the
material being cut. A blade for ripping lumber on a table
saw will generally have a high hook angle, where an
aggressive, fast cut is usually what you want. Radial arms
saws and sliding compound miter saws, on the other hand,
require a blade with a very low or negative hook angle, to
inhibit overly fast feed rate, binding, and the blade's
tendency to try to "climb" the material.
Kerf Width and Plate Thickness
The width of the "kerf" -- the slot the blade cuts in the
material - is another important consideration. Most
obviously, the kerf width determines the amount of material
that is expended in the cutting process. But kerf width
isn't just a matter of economics. The size of the kerf is
determined in part by the thickness of the blade plate, and
a solid, reliable blade plate is one of the features of a
good saw blade.
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The laser-cut reeds in this Freud thin kerf
blade are filled with a vibration dampening material
to keep the blade running straight and smooth. |
Thin Kerf Blades
A saw blade's teeth, of course, have to make a wide enough
cut to allow the blade plate to pass through the kerf. And
for the blade to operate smoothly and make a true cut
without a lot of scoring on the edge of the cut, the blade
plate has to be substantial enough to absorb vibration and
to handle the heat generated during the cut. For full kerf
saw blade, a kerf width of around 1/8'' is standard. But
for so called "underpowered" saws -- under 3 HP for a table
saw -- a full 1/8'' kerf has another effect: drawing too
much power from the tool. If not enough power is delivered
to the blade, the saw slows down causing excessive friction.
The blade heats up and can become distorted or burn the cut
surface.
Fortunately for woodworkers who don't own the most
powerful industrial equipment -- and for those of us who
just hate to watch expensive hardwood turn into piles of
chips -- technological advances in blade design have
generated "thin kerf" blades that rival the best industrial
quality full kerf saw blades. Thin kerf saw blades are
extremely helpful for underpowered saws for the simple
reason that the blade has to cut through less material, and
therefore doesn't have to work as hard as a blade with wider
teeth. The best thin kerf blades employ laser cut dampening
systems to inhibit vibration, and are made out of the best
quality hardened steel to help them stay true in the face of
high rotation speeds and stress generated in cutting.
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Quality Makes the Difference
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The thicker, oversized MicroGrain Titanium
Carbide tips are an exclusive formula manufactured
by Freud and designed specifically for each
application |
Now that you know how saw blades work, how do you judge
the quality of individual blades? It's important to be able
to judge the quality of a saw blade -- how a saw blade
performs depends on precision manufacturing techniques and
on the quality of the material that go into making the
blade.
The Best Saw Blade Teeth
One of the most important things to look for
in a saw blade is a good set of teeth. How long the blade
will stay sharp, how clean it will cut, and how many re-sharpenings
it will take all depend on the quality of the cutting tips.
These days, carbide has just about replaced steel as the
material for cutting tips of saw blade teeth. But not all
carbide is created alike. On some of the best premium
blades, the carbide is formulated specifically for the
application of the blade. At minimum, look for a blade with
C3 grade micro-grain carbide teeth, which are thick enough
to allow a number or re-sharpenings. C4 carbide is the most
durable grade for saw blade teeth, and is usually found only
on premium blades.
A Quality Blade Plate
For a saw blade to make a true cut, the teeth
must be held rigidly in line with one another. The blade
plate needs to be as close to perfectly flat as possible,
and it needs to stay that way during the cut. The blade
plate should be made of quality, hardened steel. The arbor
hole also needs to be sized and placed with extreme
precision. The best blade manufacturers like Freud and
Forrest laser cut their blade plates to insure that the
blade will fit the saw's arbor precisely and the teeth will
maintain as close to a perfectly consistent path through the
material as possible.
The blade plate also has to be "tensioned" for it to
remain straight and rigid when it comes up to speed. On a
high quality blade, correct tensioning keeps the blade
becoming "floppy" as result of the centrifugal force
generated in operation. Blade Plates can also be treated to
make their surface resistant to picking up resin and
adhesives from the materials they cut. Many Freud LU series
blades have a permanent red Teflon coating to reduce
friction and help them resist corrosion and resin build up.
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What Are the Right Blades for You?
If you've read the article up to this point, you know
enough about saw blades to choose a quality blade, and to
get the right blade for the type of sawing you need to do.
But there are still a lot of top-quality blades to choose
from. In the end, picking a saw blade has a little to do
with your personal style - the kind of tools you like to
own.
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Forrest blades are essentially "hand made." The
C4 carbide teeth are brazed in place by hand, and
each blade is individually hand tensioned and
straightened. Finally, each blade undergoes
Forrest's renowned sharpening procedure. |
If you want a blade for your table saw that will do an
excellent job of both ripping and crosscutting, will last a
long, long time, and if you get satisfaction out of owning
tools that are made individually with great care, then the
Forrest Woodworker I or Woodworker
II general purpose blades would be pretty tough to
beat. On the other hand, if you are the type who likes to
have a technologically advanced blade specifically designed
for each and every type of cutting you do, you'll take an
interest in Freud LU Industrial Series
blades.
Rockler Woodworking and Hardware has the right blade for
everything from ripping lumber to making chip-free cuts in
expensive laminates and solid surface materials. Check out
our complete selection of saw
blades right now, or if you want a few
suggestions, see Choosing the Right Saw Blade where
you'll find our Saw Blade Recommendations Chart
with our picks for the best blades for all of the most
common tools and applications.
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