A while back, I was looking at the Micro-Jig Dado Stop product. It is a blade positioning jig for table saws that lets you set the two shoulders of a dado, then cut out the space in between.
The problem that @RickKr
noticed is that many blade profiles are not flat on top. That's because most blades are designed to make through cuts, and the blade profile doesn't matter in that case.
Most general purpose and combination blades have alternating top bevel (ATB) profiles, with two angled "slicing cutters" that leave a dip in-between. Here is one example of an ATB blade that I have. Look at the tooth profile image on the right side of the web page:
What RickKr wants is a blade with a flat top tooth, sometimes called a "raker tooth". The raker tooth cuts off the extra portion between the angled tips. Here is an example of an alternating top bevel plus raker (ATB+R) that I use. Notice the profile again. This time it is left, right, left, right, raker. That fifth tooth (the raker tooth) is flat on top:
I wondered why more people don't buy the ATB+R profile blades. What is the penalty? When I spoke with a nice expert at Forrest, he told me that he wondered the same thing. He felt that the ATB+R did as well as ATB blades for crosscuts, but better, faster, and cooler for rip cuts because of the raker tooth.
My Freud SD208S (and earlier SD208) dado sets are configured in a similar way, with alternating bevels and flat rakers.
One issue with some of these ATB+R blades is the corners of the ATB stick up slightly higher than the raker tooth, to cut the wood fibers cleanly and avoid tearout. These are the well-known "bats ears" that leave thin score lines at the corners of the blade tips. When I used the Freud dado set in a two blade 1/4 inch configuration to cut widely spaced shoulders, and then cut out the in-between space with lots of small cuts, it left lots of score lines. Just sayin'.
Several companies make special two-blade box joint sets. Freud's box joint set has flat tops and is cut to eliminate the bat ears, but at the risk of more tear out and rougher cuts.
Blades made for ripping usually make flat top cuts. The teeth are often arranged in a "triple chip grind" (TCG) configuration. Because they have fewer teeth, rip cuts are fast, but not as clean. Look at the triple chip grind pattern on the right side of this web page:
I wrote the above text and don't want to lose it because it might be helpful. I just remembered that I started a similar thread related to my own research on the same topic. Included in that thread are photos of experiments that I ran with a single blade from the dado set. See this thread, particularly the photos in post 17: