Tool Review: 6" Dado Sets
Bigger isn't always better. Do the math: 6" stacked dado sets cost about $20 to $30 less than comparable 8" models, and in most cases they'll do everything their big brothers will. We seldom cut dadoes deeper than 3⁄4 ", and all 13 of the 6" sets we tested beat that by 1⁄2 ". Also, if you own a lower-powered tablesaw--particularly a benchtop model—a 6" dado set stresses its motor less without sacrificing cut quality or performance.
Before you buy, think about the materials you use most often and the types of cuts you typically make. For example, if you work only with solid wood, ignore how a set performs in plywood and melamine-coated particleboard. But if you frequently dado or rabbet tear-out-prone veneered plywood, select a set that excels at leaving clean edges in that material.
Most of these dado sets fared well in solid stock, but left significant surface tear-out on birch-veneered plywood and melamine-coated particleboard. (In fairness, some manufacturers do not recommend their 6" models for plywood or melamine. Because most of us can afford just one set for doing everything, we tested all sets in all materials to see how they fared against each other.)
If you use a dado set regularly to cut tenons or half-lap joints, choose a model that leaves flat, smooth surfaces, critical for a glue joint. Many of the models we tested achieve that. Because each set's outer blades feature beveled carbide teeth (to shear the surface fibers) rather than all flat-teeth (that leave smooth bottoms but increase edge tear-out), these sets all leave tiny scoring grooves at the outer edges of the bottom of each cut. Such grooves don't diminish the joint's strength, but can make visible half-lap joints less attractive.
All 13 sets we tested come with at least four chippers of varying thicknesses. (The top-performing sets feature four teeth per chipper instead of two.) You mix and match chippers to achieve the desired width of cut. And often you'll need to adjust the width of your dado stack in tiny increments to get an ideal fit, especially with sheet goods that typically measure less than their advertised thickness. Ten of the 13 sets include shims, but some proved easier to use than others. For example, some shims come marked with their thicknesses. Other manufacturers color code their shims. One even uses an adjustable hub on one outer blade that allows you to incrementally increase or decrease the width .004" with each click.
CMT Precision Dado 230.020.06, Forrest Dado King DK06244, Freud Super Dado SD506, and Freud Dial-A-Width SD606
Top Value: Freud Pro Dado SD206
Learn the complete results of our testing of the Amana 656030; Bosch PRO624DADO; CMT 230.020.06 and 230.520.06; Everlast DS6; Forrest DK06244; Freud SD206, SD506, and SD606; Lee Valley 15W01.03; Oldham 6005818; Ridge Carbide NW6-DM-DS; and Systimatic 37142 in the December 2008/January 2009 issue of WOOD magazine.