My
best description of how to check a sawblade’s hook angle was the ‘intersecting
line method’ that I outlined last week. My second-most used visual to help
understand this is that of a swimmer’s hand. If the hand is scooping the water,
he is using a ‘positive hook angle’, but if the hand is laid back and just
slapping water, it is a ‘negative hook angle’ effect. The swimmer won’t go
anywhere using a ‘negative hook’ hand angle, but such is not the case with a
spinning sawblade. It still cuts just fine when a negative hook angle is used,
but because it is not digging or scooping, the operator has maximum control
over the head and blade.
High-speed
steel sawblades (those without carbide tips) are not really described in terms
of ‘hook angles’ because a HSS blade truly cuts through the wood, whereas a
carbide-tipped blade ‘scrapes’ its way thru.
Years
ago, on any saw where the blade was suspended over the workpiece (ex: a miter
saw; Delta’s “Sawbuck”, a sliding miter saw, or even a sliding compound miter
saw) one would never see any blade on it, other than a negative hook. For some
reason, that has changed. Now, one might see a 12 to 15degree positive hook
blade installed on one of these saws, right out of the factory. While I am not
going to speculate as to why the manufacturer’s decided that they could do
this, I will say that I, personally, am not comfortable with it. As I told
about in my example of testing, a negative hook blade offers the user so much
more control over the sliding head, that to use any positive hook blade just
invites ‘climb-cutting’.
On
miter saws, where the head does not slide, a positive hook blade could be used
and it still be as safe as using it in a table saw (which is another discussion
entirely) because the head is ‘locked in’. There is no sliding movement as
there is on a Radial Arm Saw or a sliding miter saw. With this in mind, I can
understand it, but on a sliding miter saw? Not for me.
Hopefully,
from our discussions, you have a better understanding of some of the techniques
of a Radial Arm Saw’s blade needs. Next week, we’ll take a look at the
different styles of RAS ’s and get
a tip or two about how to go about properly aligning a RAS
Send your questions or comments to:
Toolsmartz@bellsouth.net and we’ll see what we can
do to help you
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