Note that an 8 inch dado set is appropriate for a 10 inch circular saw. It takes a lot of power to drive that stack of blades through the stock and a smaller diameter gives more power.
One interesting piece of advice is that a person should ultimately own two sets. One would be a $50 "inexpensive set" to use for non-critical uses. This would save a lot of wear and tear on the other expensive set in the $200 range.
Another caution is safety -- don't try to cut too deep of a dado as there is a great risk of kickback taking a deep cut all at once, do multiple passes and stay safe.
I have pretty much settled on getting the Freud SD508, which is the better of their two sets. It is well reviewed, and some people like it even better than the Forrest Dado King. Freud has two sets, the $100 (or less) SD208, and the top tier SD508 (for $200 - or less). The Forrest Dado King is almost $300 and some people have complained that the edges of the dado have tiny "bat ears". This is by design, the outer edges of the blade cutting first and a little deeper to avoid tearout.
Along the way, I learned that Freud has a product dedicated to cutting box joints -- in two sizes, 1/4 and 3/8. My first thought was this was a specialty item that would simply save time for a production shop and that I would be better served by the versitality of the dado set, but there is more to it than that. Here is a quote from a guy (Charles McCracken) who apparently works for Freud:
As you may know, Freud invented the Box Joint Set and our SBOX8 is very useful for its intended purposes of finger and box joints and can be used for grooves (with the grain). However, it won't substitute for a dado set for cross grain cuts because the geometry is similar to a rip blade. There are no bevel teeth to score the fibers and cuts in man made materials will not be as clean due to the high hook angle.
If you cut a lot of box joints and also have the SD508, this will save a lot of wear and tear and sharpening charges on the more expensive SD508. One fellow says he sold his dado set and now cuts dado with just the box cutter. If he needs a 1/2 or 3/4 he just makes 2 or 3 passes, worth a thought.
Using a router for finger joints is problematic in that the router bit wants to twist the stock and push it sideways. The table saw on the other hand pushes it into the miter fence, just what you want.
The Freud SBOX8 set sells for $99 list (but as low as $75 or so).
Apparently Forrest also makes a finger joint set of the same sort. It sells for $110 on Amazon (compared to $73.04 for the Freud). Forrest has a good reputation for customer service, and a stellar reputation for quality.
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