You're doing a partial body diagram, and being mighty partial about
it. Yes, the heavier blade has a greater rotational inertial force,
but a heavier-as-in-wider blade also is cutting more wood, so it has
more drag. There's no simple answer.
My take? Cut the least amount of wood you need to cut (thinnest
kerf), and buy the best quality blade you feel you can afford (their
thin kerf blades will be better than a lower quality thicker blade).
The stop worrying about it and start cutting wood.
No there isn't a simple answer, but everything else being equal, the
increased mass of a blade assists in the cutting action, like a bigger
hammer. Surely nobody is interested in too much geek detail, hence the
Readers Digest version of my statement. Not only is a more massive
rotational force advantage provable on a physical level, it is well
supported by personal observation and what industrial cutter heads
show to be most effective in their respective environments.
A set of solid 'stiffeners' on a table saw not only 'stiffens' the
blade, the added mass contributes to a better cut as well.
For sawblades kinds of masses, the inertial effects would be minimal at
best and the blade stiffener mass is concentrated near the shaft,
anyway. Besides, the inertia contained in the motor rotor, etc., is
multiples of that of the blade owing to the mass differences. Hence,
even though the blade mass may be sizable fractional difference between
the two, the system mass is essentially constant; ergo, so is the total
I have to concur w/ the dominant issue (for equivalent sharpness, tooth
geometry, etc.) being that of amount of material cut per tooth far
overriding any of the other effects.
The rotational mass of the motor is decoupled from the rotational mass
of the blade due to the elasticity of the belt. The extra mass
(regardless of how small it may be as we are not discussing HOW much
extra mass) will help smooth out the vibrations set up by the chopping
action of the the teeth of the saw blade. The issue here is mechanical
impedance. Then again, the guys at Harley Davidson don't know dick
about decoupling rotational masses either, right? OR the guys at
The more linear the tooth's attack speed is, the better the cut will
be.... and please stop throwing variables as if they're apples and
The more mass, the smoother the cut...even though it might be
minuscule in results, it bloody well is a fact. And to bring the width
and the rake of the tooth into the discussion just muddies the waters.
I clearly stated "everything else being equal".
The amount of teeth have nothing to do with the quality of the cut
assuming the feedrate is adjusted accordingly, and if your blade has
only one tooth, best you feed slowly or make that tooth go really
fast. Case in point, I can make a really nice, clean cut with a one-
toothed cutter at 25,000 RPM.
But, a few ounces as compared to the rest of the mass isn't going to be
noticeable. I've never been able to tell any difference of note between
the two on the PM66. On a small contractor saw one might have a better
I have a blade that's wider at the hub than the kerf. Sort of a built-
in stiffener, I suppose. It's a PITA if you forget it's on the saw
and the hub bottoms out on thicker wood (I think it's maximum cut is
I did not say dull, not all new blades are equally sharp.
And going a bit farther on the subject, ;~)
I was building several drawers today and got to use my "Kerf Maker", drive
by. Any way it occurred to me again why I have better results with thick
kerf vs. thin kerf. I use 1/4" plywood for the bottoms and cut snug dado's
for them to fit in to. Cheap 1/4" plywood is about 7/32" thick and the
outer and inner blades on a dado set are too wide. So I make two passes
with my thick kerf blade. With a think kerf blade that requires three
passes instead of two and also I recall when I did this long ago with a thin
kerf blade the dado width would not be constant. I suspect that because
only the outer side of the blade is cutting on the final pass the thinner
blades will deflect.
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