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| Freud®
LM74R 10" Glue Line Rip Blade |
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| Glue
up boards straight off the table saw! Traditional rip blades are made
to do one task — cut boards quickly. But the price you pay for speed is
a coarse edge that needs jointing or sanding to remove blade marks. A Glue
Line rip blade solves the problem by slightly bumping up the number of teeth
per blade (from 24 to 30) and changing the shape of those teeth for better cutting
action. |
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This blade quickly cuts stock to width without leaving blade marks and means you
can glue up boards without extra cleanup steps. Traditional rip blades are made
to do one task — cut boards to width quickly. But the price you pay for
speed is a less-than-smooth cut. Which means you have to clean up the edge. That
extra step doesn’t seem worth the time saved using a rip blade.
The reason a traditional rip blade can cut so fast is that it has fewer teeth
— most have 24 teeth. Since each tooth ends up taking a bigger bite, the
blade can chew its way through a board quickly. The trade off is that taking a
bigger bite results in a coarsely cut edge. I found a solution to my ripping troubles
in a relatively new type of blade. It’s called a glue line rip blade because
the manufacturers claim you can glue up boards straight off the table saw, without
jointing or sanding away blade marks. A glue line rip blade solves the quality-of-cut
problem without losing the advantage of high cutting speed. And the secret to
how it does this lies in the teeth. Perhaps the easiest way to get a smoother
cut is to increase the number of teeth on the blade. But the more teeth that are
put on the blade, the slower it will cut. Glue line rip blades strike a balance
by only adding a few more teeth — increasing the tooth count from 24 to
30. That step alone will make some difference in quality. But the rest of the
improvement comes from the tooth geometry.
If you look closely at a traditional rip blade, you’ll see that it has a
single type of tooth— with a flat-topped shape. In comparison, a glue line
rip blade combines a flat-top tooth with either an alternating top bevel tooth
or a triple chip tooth. The result is you have two different cutting actions going
on at the same time. The shaped teeth remove most, but not all of the waste in
the kerf. The flat teeth then follow to cleanout the rest of the waste and square
up the corners of the cut. It’s not only the way each tooth is ground that
affects the quality and speed of the cut.
The hook angle of the tooth is important, too. The hook angle is how far the tooth
leans into the cut — the higher the angle, the more aggressive the cut.
(The hook angle on most table saw blades ranges from 10° to 20°.) Since
adding teeth slows down the cutting speed, some of the glue line rip blades increase
the hook angle to make up for it. While some had an average 12° hook, one
blade had a hook angle as high as 22°.Blade Plate.
There’s more to a table saw blade than just the teeth, though. Even the
plate the teeth are attached to plays a role in making it a smooth operator. Like
most modern table saw blades, glue line rip blades have a few high-tech features
to keep the blade running straight and true. In the lower photo on the opposite
page, you’ll see expansion slots and laser-cut vibration channels. These
allow the blade to expand and contract during use without deforming or twisting
out of alignment. Besides these basic additions, glue line rip blades can incorporate
another feature — thicker plates. With fewer teeth taking bigger bites,
there’s more stress placed on each tooth. So a thicker blade plate adds
rigidity and helps stabilize the blade. A thicker plate has an added benefit.
It provides more mass to help the spinning saw blade power through tough hardwood.
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