From my experience in magazine reviews and in newsgroups it appears
there is a need to provide information to woodworkers as to the
purpose for each of the saw blade and dado designs in the marketplace.
I think I am learning, but it is not without a large amount of
effort. Does anyone know of a book or other information about the
details of saw and dado blade design? Follow me in the somewhat
long-winded explanation below:

I bought a couple of Freud dados and a trim saw blade.

Dados
I bought a Freud SD208 and an SD308 dado. The SD208 is touted as the
dado for woodworkers in the magazines. I found that the SD308 was
the best for my purposes (no blowout in crosscut of solid woods.).
The concept of what a negative hook and positive hook tooth does does
not seem to be well known. You can find info on the SD208 and the
SD508 and now there has been a lot of interest generated in the SD608
(all negative hook blades). The SD308 is called the "safety dado".
What the heck does that title do for me? I think the real message
should be that it does a great job in solid wood with little chip-out
for a reasonable price...oh, yes it also has an anti-kickback design
(to me not the number one specification).
Since I am an engineer and a user of the product as well, I think
that there is a disconnect between the engineering and the marketing
people and between the marketing people and the end user. I'll bet if
I asked the engineer why the anti-kickback feature is in the SD308 and
not the SD208, he would answer: "Because it would be very hard to
feed wood into the SD208 fast enough to get kickback, where it is so
easy to feed wood into the SD308 that you could create a kickback
condition very easily." I purchased the SD308 dado from the
recommendations of a Freud technical representative. I used this to
put grooves in the sides of a set of drawers about 3/4 inch wide by
1/4 inch deep. Let me tell you. Using this dado over the SD208 dado
was safer, faster and less nerve wracking than using the SD208. The
reason it was safer was not the anti-kickback feature. It was because
it was easier to feed and I could do the dado in one pass where it
took about 3 passes to do it with the SD208. I realize that the
easier feed pressure could necessitate the anti-kickback design, but
why feature the part that keeps one from going too fast and deep in a
dado. Does Ferrari brag about the seat belts in their cars as the
FIRST feature? The seat belts and air bags are used if the driver
pushes the car's main feature too far. The message to the end user
should be that the SD308 is a Ferrari and needs seat belts. …Quite a
different message than the Ferrari has seat belts and, by the way,
goes fast.

Trim saw blades
In researching blades for the Dewalt trim saw, I was completely
confused. The Woodcraft Supply and local wood machine suppliers do
not really know the difference in blades that are available for this
saw and the literature I have seen is not clear. Freud says that
their TK004 is the BEST for plywood. I wonder if there are other
people out there that would love to know that. I don't know where I
can find that blade in the local area (Ann Arbor, MI). Electric Tool
and Supply on State Street was the only place locally that I know that
had the TK003.
In the full-line Freud catalog, the 5 3/8 trim saw blades are
described. Although the specifications are shown in detail, there is
no performance distinction between the TK003 and TK004. Is that
really true? I believe that if I were very concerned about plywood, I
would want the TK004 (which no one sells locally and I would have to
buy on the Internet). I bought the TK003, but I think I would gladly
pay the difference in price (about $18 for TK003 vs. $24 for the
TK004) for (what I perceive would be) the difference in performance in
plywood.

Negative rake = blade does not have a tendency to pull the workpiece into
the blade. Allows more user control of the workpiece.
Positive rake = blade has a slight tendency to pull the workpiece into the
blade. Allows easier feeding and sometimes faster cutting, but often not as
safe or as accurate.

You will likely find negative rake on all good dado sets.
FWIW, I have an SD208 set and had no problems so far.

If you are after some good info/review on the Infinity Dado Set, try he
http://www.onlinetoolreviews.com/rev...ydadonator.htm

--
Regards,

Dean Bielanowski
Editor,
Online Tool Reviews
http://www.onlinetoolreviews.com
Over 50 woodworking product reviews online!
------------------------------------------------------------
Latest 6 Reviews:
- Infinity "Dadonator" Stacked Dado Set
- GMC LS950SPJ Scrolling Jigsaw
- Triton Powered Respirator
- Veritas Power Tool Guide
- Ryobi 6" Grinder/Stand Combo
- Band Saw Handbook
------------------------------------------------------------