Three new 8-in.-dia. dado-blade sets recently came on the market. Bosch introduced two, one with 24 teeth and one with 40 teeth. CMT introduced a 12-tooth set. All can cut dadoes up to 1-3/16 in. wide. I gave each one a cutting test in my shop.
Testing procedure
As a basis for comparison to other dado blades, I followed the procedure used by Steve Latta when he evaluated 15 dado sets in FWW #176. I tested each blade by cutting melamine and veneer plywood. The plywood was cut across the grain of the face veneer.
I made up samples of each material, 3/4 in. thick by 12 in. wide by 16 in. long. I then set up the dado set to cut a 3/4-in.-wide by 1/4-in.-deep dado with each pass, making 22 passes on each sample of material for a total of 44 cuts with each blade.
I evaluated each cut for tearout on the face of the material and whether the bottom of the cut was flat and smooth, including scoring at the corners (see results below).
Compared to the Bosch sets, the CMT required a bit more force for a given dado width, and slower speed across the blade for a tearout-free cut, no doubt due to the fewer number of teeth. But the bottoms of the dadoes and rabbets were very flat.
Which would I buy? Considering that the CMT costs much less, created flatter bottoms, and produced no more tearout at a slow feed rate than the Bosch sets, the CMT would be my first choice.
From Fine Woodworking #196
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