Using a Dado Stack Buildup on the Table Saw
George VondriskaDado joints provide herculean strength while being relatively simple to mill on a table saw, making them the obvious choice when it comes to cabinet carcase construction. If there is a catch, it is that getting your table saw set up properly with a dado stack to accurately mill dadoes to the correct width can be a frustrating experience We woodworkers are accustomed to working in increments as fine as 1/32” or even 1/64”, but getting a proper fitting dado joint requires working in tolerances of a few thousandths of an inch. Never fear, George is here to show you how the pros do it!
Before diving into dado construction, it is important that you are comfortable using a table saw. If you want to brush up on that skill set first, perhaps you want to view a table saw video. From there, you can start thinking about setting up your dado stack.
Don’t accept less than a perfect fit
When setting up your dado stack, you’ll want to ensure that you achieve the correct fit using the material that you will work with in your actual project. If the fit is too loose, you face a risk of joint failure, which is one of the greatest embarrassments that a woodworker can experience. If the fit is too tight, you can starve the joint of glue as you force the members together, or worse, crack the work piece.
Develop a “cheat sheet”
The key to success is to invest the time once to create an index with common dado sizes, and keep this available as you set up for dado joints in the future. This will pay dividends over the years as you’ll save time and gain accuracy every single time you use the jig.
We're gonna create a dado here on the table saw using what's called a stackable dado head. So a stackable head is a rim blade. We'll have a second rim blade on here. In between there's a bunch of chippers, maybe some dado shims, and the question becomes, for the material that we are using today, this a piece of walnut veneer at MDF how thick is that really? and more importantly how thick is it relative to the width of the dado head?
So here's a great trick for this. At one point what I did, is I took a piece of material. This is also MDF, and I set up my dado head too twenty three, thirty seconds. And I made a cut. Then I added a 5000 shim, and I made another cut.
Then I added another 5000's cut, made a cut, made a cut, Each cut in this board is five thousandths of an inch larger than the previous cut. What that lets me do is grab my material that I want to create the dado for and what I need to do is start down here at twenty three, thirty seconds And see does it go in there. Nope, too big. Still too big. Ope, three quarters, not bad.
So, not bad. What I'm looking for is it should slip in with hand pressure, but there should be a little friction on it so that when I lift this board up the part I dado'd comes with it. So let's come back down to this one. So, twenty-five thousandths over my twenty three, thirty seconds. It's just a little bit too small full three quarters is just a little bit too big.
So what that helps me do now is come to the rim blades, the chippers, my combination of cutters here, and create a build up that's pretty darn close to being right. So, here's what we're going to do. I'm going to take and put my last chipper in there. Which is my three, thirty seconds. Unless I've already got it in there.
Let me check. Yup, that's already in. And then with this particular set of dado shims they're color coded, so I'm going to grab the combination of color coded shims that's gonna work for this. Put on my last rim blade, and we'll try a cut and see how this does. Set the height of my blade All right, gonna plug the saw in and then we'll make a cut and see how we came out.
Now okay, I overshot just a little bit. So this is a great lesson. What do we do when we overshot? If the dado that you cut is a little bit too big we can now use our dado shims to figure out how much too big. So I've got a gap.
That dado Shim fits. Uh, that one fits but it's pretty tight. So what I can do is look at my color code, and now I know, if these are twenty thousandths each I need to take that much out of my buildup in order to get just the right size dado. So I'll keep working with that setting until I get the perfect fit. I'm gonna take some shims out and we'll go after this again.
So, the dado jig really goes a long way toward getting you focused in on what combination of rim blades, tippers, and possibly dado shims you're going to need to get close to the fit. Even with this I'm always going to do a test cut first on waste wood and then dial my dado in from their. Again the fit we're looking for is push that board in by hand, And their should be enough friction that they stay together when you lift them up. So checkout and try that jig for cutting dado's, and you'll be able to take a little bit of a shortcut too perfect dado's on your table saw.
Does it matter how the chippers are positioned with the blades?
I love the dado jig idea, but I've found another shortcut I'd like your thoughts on. Using the concept of the Rockler dado jog (for routers), you use a 1/2" bit to plow out the bulk of the dado on one side of the cut, then move the router to a different channel in the jig and cut the remaining width (something less than 1/2""). I transferred this process to the table saw, putting in a 1/2" dado stack and making the first cut on the right-hand shoulder of the layout line on a test piece. When that setup is perfect, I make the first cut in all of my work pieces. Then, I return to the test piece and simply move the table saw fence close to, but not quite, the full width of my dado and cut the remainder of the dado. I check the fit, sneaking up on it until I'm happy; then, with the fence set properly, I can make the final cuts in the work pieces. I find it easier and faster to move the fence vs. unplugging the saw and adding and testing shims. Your thoughts?