Saw
Blade Components and Tip Configurations
Saw
Plate The body, which is
obviously the backbone of the blade, is made from a high carbon, chrome,
nickel and special moly-alloy steel. The steel will add durability by
preventing warping during heat buildup and strength by absorbing initial
shock pressure when cutting hard materials. Our plate tolerance is kept to
less than .003 inches. Plate tolerance (side to side wobble) or "run out"
of the saw blade is a key test of quality. If the plate tolerance is not
kept within certain specifications, it may affect the grinding of the
carbide tip or "high speed flutter" more commonly known as saw blade
noise. Plate tolerance is a key factor to extremely smooth cutting in a
very quiet environment.
Kerf The width of the
carbide tip measured from the two widest points of the top of the carbide
tip. The kerf on a carbide tipped saw blade acts as the set in the blade
giving it the clearance it needs to cut through the material
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Kerf and Plate
Thickness Kerf determines the
width of the cut and plate thickness determines the amount of relief
between the material and the
blade. |
Arbor
Hole The center bore
joins the saw blade with the saw. Its function is critical, for no matter
how good a saw blade or saw is, if the arbor fit is not exact, neither
will function at maximum efficiency. We use hand tested meters and gauges
to assure the exact diameter arbor.
Diameter The
diameter is measured from the furthest edge of one tip to the furthest
edge of the tip directly opposite. Generally speaking, the larger diameter
blades are thought of as industrial quality for two reasons: 1) a larger
diameter can facilitate more teeth for a smoother cut and 2) with a larger
diameter, each tooth will have to work less and the blade will last longer
as a result. We manufacture blades which range in diameter from 3-3/8" up
to 18".
Gauge The
measurement of the plate thickness. Generally, a heavier plate will be
stronger and more durable. The gauge goes hand in hand with the steel saw
body in that a heavier plate will absorb the initial impact of the cutting
edge better than a thinner plate. CAUTION: Too heavy of a plate must also
be considered, as some saw machines have reduced horsepower for economical
purposes and a heavy plate may tend to drag on the motor.
Shoulder The
shoulder's major functions are to add strength and support to the carbide
tip. A well-designed shoulder will help strengthen and guide the carbide
tip through the material being cut. Its design must be considered in
conjunction with the number of teeth, hook angle, and gullet. A larger
diameter blade can easily facilitate 60 to 100 teeth without sacrificing a
strong shoulder design.
Gullets The
main purpose of a gullet is to provide clearance for the material being
removed. The design of the gullet must be done keeping in mind such
factors as material being cut, type of cut (rip or crosscut and smooth or
rough), speed of the cut, type of tooth design and pitch or hook angle of
the teeth. For example, a Rip saw blade is designed to cut very quickly
along the grain of the wood. It has fewer teeth and a large gullet to aid
in the removal of sawdust. By contrast, a Crosscut blade will have a
smoother, slower cut against the grain, therefore having more teeth and a
smaller gullet design. The major issue to consider in design is to have no
sharp or square corners as they will lend themselves as a natural stress
or fault line in the saw blade.
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Gullet The gullet is
a relief area cut in front of the tooth which provides a temporary
place to store the material cut away by the tooth on each revolution
of the blade. |
Hook
Angle The hook angle is the amount
of forward or backward lean each tooth has. The angle is measured by the
intersection of two imaginary lines. The first line is drawn flush with
the face of the carbide tip and the second is drawn vertically while going
through the center of the arbor hole. Basically, the greater the hook
angle a blade has, the more pull or grab the blade will have on the
material being cut. A rip blade has a large positive hook angle so it will
cut very quickly. As the hook angle approaches zero degrees and even
exceeds zero (negative hook angle), the blade exhibits no grabbing at all.
This is important when cutting metals, where total control over the feed
is needed.
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Hook Angle:
Aggressive 20 degree
positive hook angles found on rip blades pull the wood into the
blade. Standard hook angles range from 5 to 15 degrees positive.
Negative hook angles, usually -5 degrees, are used to prevent
self-feeding of materials and give the operator maximum control over
the feed of cut. |
Number of
Teeth This is one variable that
will have the most noticeable effect on the cutting action of the saw
blade.. As the number of teeth increases, the blade will have a tendency
to cut very smoothly but slower than a blade with fewer teeth. Also, as
the number of teeth increases, the distance between each tooth is
decreased therefore reducing the size of the gullets making chip ejection
from the gullet more difficult. This is where the design of the gullet,
shoulder, tooth style and hook angles become of the utmost importance.
Placing more teeth in the same amount of space can only be successful if
everything matches perfectly.
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Carbide
Tooth: Carbide is an alloy
composed of Cobalt and Tungsten. This alloy gives longer lasting
tips, sharper
cutting edges, and greater impact
resistance. |
Expansion
Slots The basic function of the
expansion slots, which are used primarily on larger diameter blades is to
create an outlet for heat buildup created during cutting. For example,
imagine a 10" piece of steel with 60 or 80 carbide teeth turning at a
speed of 6,000 RPM entering a piece of hardwood such as oak. A great deal
of heat is built up by a combination of factors including friction,
centrifugal force and the cutting material itself. Even the very best
steel blade will heat up to a point where the heat is great enough to
force the steel to expand. When this happens the heat (or forced
expansion) must have an outlet. The expansion slots allow the steel to do
just that, expand and contract without warping the steel or destroying the
tension of the blade.
Expansion Slot
Base Holes The Expansion slot base holes
are round geometric shapes with no sharp or square corners. A round
geometric figure will take the stress of initial impact pressure from the
carbide tip entering the material and disburse the pressure evenly
throughout the body of the saw, otherwise the blade may crack on that
stress line.
4 Types
of Carbide Tipped Tooth Configurations
Carbide
Tips A carbide tipped blade will stay
sharp approximately 10 times longer than an ordinary steel blade. The
reason is that tungsten carbide, a man made substance, is one of the
hardest materials known to man.
Square
Top Tooth
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Square Top
Tooth The top of each tooth
is ground square, perpendicular to the sides of the blade. Square
Top Grinds are designed for heavy duty cutting.
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Advantages: 1. It cuts both sides
of the kerf simultaneously, making it twice as effective as teeth in a
staggered tooth saw in which each tooth cuts only one side at a
time. 2. Its balanced cutting forces reduce saw body stresses. 3. It
has large included angles between cutting edges that strengthen the tooth
form and keep it sharp for longer periods of time. 4. The tooth form is
relatively easy to maintain. Disadvantages: 1. The tooth form
generates relatively large cutting pressure and this contributes greatly
to chip out or tear out at the exit point on the material. 2. Low side
clearance angles inhibit the freedom of chip flow. The chips generated in
the cut drag on the side of the cut causing a buildup.
Alternate Top
Bevel (ATB)
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Alternate
Top Bevel (ATB) The tops of alternating
teeth are beveled to one side of the blade or the other at
approximately 15 degrees. This tooth configuration bears a sharp
pointed tip that provides a neat clipping action for very fine
finishes. Two teeth will span the width of the
kerf.
Alternate Top Bevel
Design shear cuts the material for clean cutting without chipping or
splintering. For use on cutting wood, plywood, veneer, hardboard,
fiberboard and particle board. |
Advantages: 1. It produces very
low cutting pressures that almost eliminate the tendency to tear
out. 2. The chips fall free in the chip spaces created by the large
side clearance angles. Disadvantages: 1. The leading
point is susceptible to wear and damage from shock loads. 2. Cutting
forces perpendicular to the beveled edge result in semi-lateral thrusts on
the saw body. 3. In sharpening it is difficult to maintain an equal
bevel and equal diameter across the points of the teeth around the
saw.
Triple
Chip
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The first
tooth, or lead tooth, has a double 45 degree angle corner bevel.
This is followed by a flat topped raker tooth ground lower the the
lead tooth. The raker tooth removes the corners left on both
sides by the beveled lead tooth. Triple Chip Grinds combines a
balanced cutting force, low tooth drag and free chip flow. For use
on cutting hardwood, plastics, and plastic laminated to wood.
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Advantages: 1. Large included
angles in the cutting edges give the triple chip form good wear
resistance. 2. A balanced cutting force. 3. Low tooth drag. 4.
Free chip flow. Disadvantages: 1. The triple chip
tooth form requires extra maintenance care to avoid the risk of changing
tooth forms during sharpening. Alterations can lead to deteriorated
cutting action. 2.This triple chip tooth form has strong blunt edges,
there is a relatively low shear generating high cutting pressures which
tend to produce chip outs.
Planer-Combination
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Planer
Combination combines 4 Alternate Top Bevel Teeth with 1 raker. The
basic function of the raker tooth, which is lower than the tips of
the scoring teeth and narrower: it removes the V-shaped piece
of material left in the center of the cut by the alternating top
bevel teeth. This tooth configuration provides a very smooth
cut. |
Advantages: 1. It produces very
low cutting pressures that almost eliminate the tendency to tear
out. 2. The chips fall free in the chip spaces created by the large
side clearance angles. 3. A balanced cutting
force. Disadvantages: 1. The leading
point is susceptible to wear and damage from shock loads. 2. In
sharpening it is difficult to maintain an equal bevel diameter across the
points of the teeth around the saw.
Glossary
of Saw Blade Terms
Anti-Kick
Saw Blades:
Saw Blades with
anti-kickback shoulders that limit the amount of material that can safely
be cut by each tooth. This virtually eliminates the kickback caused by
overfeeding. Also called safety saw blades.
Anti-Stick
Coatings: As used on
saw blades, these coatings decrease friction and heat buildup and help
provide cleaner, smoother and quieter cutting action. Anti-stick
coatings also resist resin and pitch buildup and improve safety
conditions.
Arbor: The shaft, driven by the saw's motor, which
turns the saw blade. Also called a mandrel.
Chipper: In dado sets, small cutting tools with varying
widths. Chippers are places between the cutters, or the outside blades, of
the dado set to adjust the width of the cut.
Chipping:
The condition caused
when the saw blade lifts and tears the wood fibers as it exits the
material. This causes the edge of the cut to be ragged.
Clearance
Angle: The angle
between the lower face of a saw blade and the material being
cut.
Combination Saw
Blade: Saw blades used for both ripping
(cutting with the grain of the wood) and crosscutting (cutting across the
grain).
Crosscut: A cut made across the grain of the
wood.
Cutoff:
Refers to the smooth
cutting of wood, plywood, chipboard, paneling, pressboard, etc.
Cutter: In dado sets, the two larger, outside
blades.
Cutting
Angle: The angle
between the upper face of the saw blade and the material being cut. Also
known as a rake angle.
Dado:
(1) A flat-bottomed
recessed cut made across the grain of a board. (2) A b> Dampener: Used to
improve saw blade performance by stiffening the saw blade plate and
dampening sound and vibration caused by the saw's belt, motor, and
bearings. Dampeners are mounted on the saw's arbor directly next to the
blade. Also called a saw blade stabilizer.
Ferrous: Of or
containing iron.
Finishing
Saw Blade: A saw blade with higher tooth counts to provide
smoother cuts. Typically refers to 7 1/4 inch blades with more than 40
teeth and 10 inch blades with more than 60 teeth.
Framing
Saw Blades: Carbide tipped saw blades used to make fast sizing
cuts in all types of wood. (the fastest cutting is achieved with thin kerf
saw blades.)
General
Purpose Saw Blades: Saw blades with low tooth counts used for
fast crosscutting and ripping in most woods and wood-related materials.
This designation is commonly used with opening price point carbide
blades.
Groove: A recessed cut
made across the grain of the wood. A groove has two straight sides that
are at a 90 degree angle with a flat bottom. See also Plough.
Hollow
Ground: A concave bevel edge on a tool.
Miter: The process of
cutting material for an equal angle joint.
Nonferrous: Materials
and metals not of or containing iron, such as aluminum, copper, brass and
lead.
Plane: In woodworking,
to make a surface smooth or even.
Plough:
A recessed cut made with the grain of the wood. A plough cut
has two straight sides that are at a 90 degree angle to a flat bottom.
See also Groove.
Precision
Finishing Saw Blade: Precision sharpened saw blades with a high
tooth count and thicker kerf. These blades provide very smooth cuts in
hardwood, softwood, plywood, chipboard, paneling, and Marlite.
Rabbet:
An open-ended cut made along the edge of a workpiece that
receives or interlocks with another piece to form a joint
Ripping: The process
of sawing a board in the direction of the grain of the board.
Runout:
The amount of wobble in a saw blade, or how much the blade
moves from left to right during use. Also called wobble or warp. Our saw
blades have very little or no runout.
Shim: (1) A thin,
often tapered piece of material such as metal or wood used to fill in
space between things. (2) A round, usually magnetic disc used with a dado
blade to provide a wider cut.
Stopped
Groove: A cut made along the grain that stops short of one or
both ends of the workpiece.
Tear-out: A condition
in which the saw blades tears out the grain of a workpiece.
Thin Kerf
Saw Blades: A saw blade with a kerf, or cut width, between .065
and .070 inches.
Worm Drive
Saw: A saw that has a diamond-shaped arbor instead of a round
arbor.
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