Video: How To Cut Dados With A Table Saw & Dado Set
A dado joint is a flat bottom channel that is cut to fit the width of another piece of wood. They are perfect for supporting shelves in cabinets or dividers in boxes. We show you how to cut a dado using a table saw and stacked dado blade set.
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Video: How To Cut Dados With A Table Saw & Dado Set - Video Transcript
Speaker 1: Now there's a number of different ways to cut dado joints but typically it's at the table saw with a dado blade set and this is sometimes called a dado head and it's really just a sandwich of saw blades. You get two blades that look pretty similar to standard saw blades and they form the outside walls of the dado cut. Then you also get a number of what are called chipper blades. Now, these will have two to four teeth on them depending on the manufacturer and the teeth are cut at different thicknesses.
You can stack your chipper blades in various combinations with the outer blades to make any dado width you need up to about an inch. You'll also need a throat plate for your table saw that has an opening in it that's wide enough for the dado you're cutting and you'll need your saws miter gauge. It's a good idea to attach a sacrificial fence to your miter gauge. That'll back up the back edge of the cut to keep the blade from splintering out the wood there. This sacrificial fence also provides more bearing support and that's helpful if your dado wing along bookcase side for instance and pushing that through the blade.
Now making cuts with the dado blade really isn't any harder than cross cutting with a standard blade but it is a little tricky getting the cutting width just right. Here's what you're going for. You want the parts of your joint to fit together nice and snug without any extra slop. Now you could just try randomly putting your dado set together and measuring the blade width and making some test cuts until you stumble on the right width but there's a faster way to get right into the ballpark.
Set your outer blades on a flat surface and so the teeth aren't touching one another, then take the workpiece that you're going to fit into the dado, set it next to your outer blades and stack the chipper blades on top of the outer blades so the teeth aren't touching. Keep stacking them up till you find an arrangement that's flush with the top of your workpiece.
Once you achieve that you should have a near-perfect dado fit. If you don't get it just right dado sets come with a stack of metal or plastic shims of different thicknesses. If your dado width is a little bit undersized, you can use one or two of these shims placed between the chipper blades to make up that extra width. Once you land on what seems like the right width, go ahead and load it in your saw. When you load your dado blade on your table saw, two quick things I want to point out. The outer two blades aren't interchangeable on the stack, the teeth on one blade faces to the right and on the other blade pitch to the left.
Load the outer blades so that the points are facing outward and typically the easy way to know which way that is is to face the logos of the two blades outward on the stack. Also when you're loading your chipper blades, don't line the teeth up with one another. Fan them out in relation to one another like a deck of cards. The only thing that should be making contact between the chipper blades are the blade bodies, not the teeth.
With the blade installed raise the blade to the cutting depth you want and make a test cut on a scrap workpiece, hold the workpiece securely against the miter gauge to keep it from shifting left to right when you make the cut. Let's go ahead and check that test cut. Oh, that's a good fit. Now if my dado had been too loose, I'd have to take one of the chipper blades off, find a thinner one and possibly shim it out to get a better fit. If the dado was too tight, I'd have to add a shim or two to widen the cut just a little bit and that's the importance of making test cuts when you're making dado joints.
Once you've got your blade dialed in, and you've made a couple of test cuts to verify it, mark your actual workpiece and cut your dado just like you made your test cuts. Dado joints are fundamental to woodworking and you'll use them again and again in your projects. Now that you know how to make them, they're a piece of cake.