Size of Dado Head

One question I've heard a lot from woodworkers is, I've got a 10 inch blade on my table saw, it says right on there it's a 10 inch saw, but I went dado shopping, and I couldn't find a 10 inch dado head, what's the deal? Well, here's the deal. There are 10 inch dado heads out there on a big industrial scale, but that's not what we wanna use on these woodworking tools. What you're looking for is an eight inch or a six inch dado head. So I've got a couple of examples here. This is an eight inch head, this is a six inch head. Now, here's the deal. When we build this dado hat up to it's full width, we can get all the way out to 13/16ths of an inch. So we're taken out a lot of wood. If this blade were 10 inches in diameter, and taking out that big path of wood, there'd be a lot of leverage against the motor, there'd be a lot of force. Take a lot of torque to get that all to cut, very, very hard on the motor. Additionally, when we put this dado head in our saw, eight inch dado head, and we raise it above the table, it actually comes outta the table almost two inches. Well, that's plenty of depth of cut for most of what you're gonna use a dado head for. In fact, the reason that a six inch dado head can be handy is, if you're on a contractor saw, with the typically smaller motors, about 1.5 horsepower, the six inch dado head will exert less torque against the motor than the eight inch will. So it's not a bad idea to stick with the six inch. Now as an experiment, if you wanna see on your saw exactly how much each different dado head will give you for depth of cut. It's very simple. Take a piece of cardboard, cut a six inch circle, put a hole in the middle. You can put that on the arbor of your saw, raise it as high as it'll go. You'll see how much the cardboard projects above your tabletop. It'll tell you what the depth of cut from that dado head, or an eight inch dado head will be once you have it mounted on your saw. So, quit looking for something that ya can't find, which is 10 inch dado heads. Again, we wanna stick with six or eight. For many woodworkers, a six inch dado head is gonna serve 'em just fine. You do wanna try to match it up to the horsepower that your saw provides.