Pros: Great performance and features from a reasonably priced dado set.
Cons: Made in China
This DW7670 is DeWalt's latest 8" stacked dado blade set. It features (2) 24 tooth outside cutters, (4) 4 tooth 1/8" chippers, (1) 4T 1/16" chipper, (1) 4T 3/32" chipper, (12) steel shims, and a handy carrying case. The DW7670 expands to a maximum cutting width of 29/32", and has a nearly infinite number of possible smaller widths by using the various shim and chipper sizes. All the teeth are micrograin carbide, and the bore diameter will fit 5/8" arbors. The width of each blade and each shim is clearly marked for easy identification. DeWalt backs the DW7670 with a 3 year warranty and 1-year free service contract.
The DW7670 is my third stacked dado set. It replaced a very good Freud SD208, which replaced a lesser quality steel Vermont American stacked dado. The high tooth count and a sale price piqued my curiousity. Note that none of my dado sets have been "wobble" dados, which aren't physically capable of delivering a truly flat bottom. The resultant cut from a wobble dado is more of an arc. The terms "wobble" and "power tool" just don't sound right in the same phrase to me, so my advice is to skip the single blade wobble design altogether unless the lack of precision is acceptable to you. The first thing that caught my attention when I opened the DW7670 is the carrying case. There's a useful compartment with easy access for everything included in the set. The feature that drew me to the DW7670 initially was the number of teeth. The 24 tooth cutters and 4 tooth chippers have double the respective number of teeth as my SD208 set had, which should result in a cleaner cut if all else is equal. The set is well made with quality materials, though the teeth are not as large as those on my Freud dado, but they seem adequate.
The entire design of the DW7670 is different than my SD208. In addition to having twice the number of teeth, there's also no anti-kickback fingers on the DeWalt like there are on the Freud, which is a nice safety feature that may be a consideration for some. The design of the DW7670 is more similar to the top notch Forrest Dado King with a street price that's considerably more expensive than the DeWalt dado set. The number of teeth on the 7670 are comparable to Freud's SD508 which is also a more expensive blade set. The chippers on the Forrest and the DeWalt sets are tapered toward the outside of the blades, whereas Freud's chippers are closer to the same width across the length of the blade to accommodate the anti-kickback fingers. In use, this design difference translates to noticeably faster startup and less bogging with the DeWalt on my saw. Because the chippers are tapered, the mass is lighter at the outside of the 7670 than the Freud, making it easier to spin. This makes sense from a physics standpoint, although it's not a characteristic I had anticipated. It's likely that this would be a non-factor on a larger saw, but was a pleasant surprise for me nonetheless, equating to more usable power from my saw while spinning the DeWalt dado. In addition to less slowdown during heavy cuts, the 7670 made exceptionally clean cuts in a variety of materials. My SD208 was a very good performer and I don't want to take anything away from it or it's value...the bottoms of cuts were geometrically flat and edges were reasonably clean, but the DW7670 simply leaves a cleaner cut. The SD208 left minor "striping" on the bottom of dado cuts that the 7670 does not leave, a phenominom also noted by Wood Magazine in their dado comparison. Edges are also moderately cleaner with the DW.
The identification feature on the blades and shims seems minor from a glance, but in use are a very practical and convenient addition that my Freud set did not have...it's especially convenient on the shim stock where the small width differences are hard to discern by eye. The shim stock also seems better made than those with my Freud set. The shims on my SD208 were prone to becoming disfigured near the bore and folding over rendering them useless. The instruction manual contains useful guidelines for the correct combination of blades and shims to achieve a given desired width, and the manual folds nicely and stores away in it's compartment in the carrying case. The addition of the sixth chipper (3/32") is also very convenient and lends itself nicely to real world plywood widths. Many sets only offer 5 chippers in two widths.
My one and only complaint with the 7670 dado set is the country of origin. My other series 40 and series 60 DeWalt blades are made in England. The DW7670 is made in China, which was an unfortunate and disappointing surprise to me personally but may not be an issue for others. The 7670 enjoys the wide distribution of DeWalt's dealer network and can often be found on sale in the $90 range.....likely a result of being made in China. That being said, it does offer the design features and performance of a more expensive American or Italian made dado set. Highly recommended from a performance and value perspective.