Rabbets, dadoes and grooves are basic joints we use in woodworking time and time again. Properly cut, it really improves their appearance and their strength. But before I show you how to cut them, let me describe what each one of those is.
The first is a rabbet and by definition a rabbet is made down the end of a board and you can see it here on the edge of this piece of plywood.
A dado is cut across the width of a board, that’s a U shaped groove right down the middle that’s this one.
Lastly we have a groove and by definition a groove is cut down the length of a board and you can see that displayed here.
All of these can be done on either a router or a table saw and what I want to do first to show you how they’re cutting a table saw.
Watch the video below.
What Kind Of Table Saw Blade Do I Need To Make Rabbets, Dadoes and Grooves?
When we’re cutting these joints in a table saw we’re going to be using a dado blade, and I’ve got one set up on the saw now. The two outside blades here are standard eighth inch blades, almost like regular table saw blades, and on the inside here are called chippers.
They range anywhere from an eighth of an inch down to just about a 16th of an inch. And when you combine those with some shims, you can get a dado with set that goes from a quarter of an inch up to a little bit over three quarters of an inch.
I’ve got this setup now for about three quarters and we’re going to show you how to use that to make dadoes, rabbets and grooves.
How To Cut A Rabbet Joint With A Table Saw.
So the first joint we’ll cut is a rabbet joint and a rabbet joint is this one on the edge of the board. Now there’s two ways to do that. I’ve got the dado blade set in here; you can reduce the width of that dado blade to match the width of that rabbet.
So you take out a few of the chippers or add a couple of shims to match that and of course raise the height to match the depth of this cut or you can leave the full width dado, raise that into a sacrificial fence and use the exposed part of the dado to cut that rabbet.
In effect that’s what most woodworkers wind up doing because if they want to adjust that rabbet a little bit deeper or shallower, they have a full width dado in there already, just by moving the fence in or out it allows for that adjustment. What it’ll do is cut a small recess in the face of this, give a little bit of room for that blade.
Once I’ve done that, I can turn off the saw. I’ll then measure the width and height of that dado and use my sacrificial fence as a guide to drag this over the top to put that rabbet on the outside edge of the board.
So we’ll start first by lowering the blade. We’ll slide the fence over the top of it and slowly raise the blade into that sacrificial fence.
I now have a small groove or recess in the face of that. I can go back and raise my blade and match its height to the depth of the rabbet that I want here and I can use this board that I’ve already done to give me an idea of what the height will be and that’s about where we are there.
And I want to expose just a little bit more of the blade. So now I’m getting exactly the right pass. So now I can take my fresh board, turn the saw back on again and cut my rabbet.
So here’s the rabbet cut on the side of the board and again because I’ve got a full width dado blade on there, let’s just say that I want that rabbet a slightly deeper. That’s pretty easy now because all I’ll do is move the fence back just a bit and recut that same rabbet. So here is our recut wider rabbet.
How To Cut A Groove Joint With A Table Saw.
To cut a groove, and remember a groove runs the length of this stock. We don’t need a sacrificial fence. All we need is a regular fence and our dado blade set to whatever the width of our groove is going to be.
To get that alignment, we can either use a prop like this one, one that you’ve already set up to give you the distances for all the things you’re doing or you can measure across the fence to the inside or the outside depending upon your setups.
But once the fence is locked in, all you’re doing is raising the blade to the correct depth and running it over the top of the blade. It’s real easy to do a groove.
How To Cut A Dado Joint With A Table Saw.
When we’re doing a dado, a little bit different—a dado, remember, we’re coming across the wood. Most cases are going to be a little bit narrower. So what we want to do here is get the help of a miter gauge to gives us a little bit more support. And again, we’re going to measure from the fence over to the blade, or we’re going to use a preexisting stop like this one to kind of guess about where that groove is supposed to go.
But once I make that adjustment and lock that in, I’m going to be using the miter gauge and the fences as a port for that pieces that goes across. And just to add a note of caution.
This is the only time that you can use a miter gauge with a fence. We’re not cutting through and through cuts. There’ll be no off cut piece when we’re done. If there were an off cut piece and you’re trying to work between a miter gauge and a fence, that small piece here is not supported. You greatly increase the chances or potential for kickback.
This works really easily and again the blade is set to whatever height and width from the fence and a pass is made across the wood, done multiple times, gives you all of the dadoes that you need on the side of a shelf or in a bracket for what you’re planning on holding, works really well.
How To Set Up Your Dado Blade To Get Perfect Joint Fits.
Now here’s a plywood shelf inserted into a dado. I don’t think that you’re going to find a much tighter, nicer fitting joint than that. If you can do this, you’d be one happy woodworker. Let me show you how we did it. One of the problems about doing shelving units or any other project that involves plywood is that plywood really isn’t as thick as it’s sold as.
If you buy a piece of three quarter inch plywood, it really isn’t three quarters of an inch just slightly thinner. So if you set a dado blade up to cut a three quarter inch wide groove or dado, you’re going to find that the groove or dado is too wide.
So one of the ways to make that perfect and do a one cut setup to make those pieces fit perfectly is to take your dado set like I’ve done here out of the saw. I’ve stacked them up. We have our top plate here and we have a stack of chippers in the pile and I’ve also got a few shims.
These shims come packaged with your dado set. And I’m going to add a few shims here. Until—what I’ll find is that my dado blade when set up is slightly higher than the board that I’m planning on inserting into that dado or that groove. And I’ll keep adding these little shims until I’ve got it high enough.
So in this case with the shims in there, I can feel at the edge of that cutting tooth is actually higher than the board. So I’m going to be cutting a groove that’s slightly wider. That’s my test cut and that’s the only time I’ll have to do it. Let me show you how this works.
So what I’ve got is I’ve got a groove that is slightly wider than the shelf I’m planning on putting in. And you can see it kind of wanders a little bit on the inside. So to make this fit exactly, I’m now going to remove shippers. I’m sorry—I’m going to remove the shims to make up for that sloppiness.
So I’ve got these shims out, and I think I’ve got enough of them out to make the difference. So here’s the shelf we’re planning on inserting. There’s just a little bit of slop in this opening. So now by taking some of these shims and putting them back in this slot—I’ll keep doing that until they make that fit real tight.
There’s still a little bit of movement in there. That one’s a little too much. Just to play with this just a bit here. Actually that one shim is perfect. So by removing that shim and putting these back the cut that I get out of this will match perfectly the board that I’m planning on inserting.
Here’s the test. That piece of plywood fits perfectly in that opening. There’s no slop, there’s no movement. It’s a great way to set that dado blade up to cut the perfect grooves for plywood when it doesn’t match the exact width of a standard dado set—works really well.
How To Cut A Rabbet Joint With A Router Table.
I’ve come to the router table to show you how to put a rabbet on the edge of a board. One of the reasons I like a router table is it’s much easier to work on small pieces on a router table or handheld router maybe a little bit too big for this, a little bit too awkward.
Well, there’s two ways to put those rabbets on. The first is by buying and using a dedicated rabbeting bit and I have one here. This particular one has a lot of mass. It provides a really nice clean rabbet, but more importantly, it’s got a series of bearings that you can buy with it.
So the bearings will determine how wide that rabbet is, the depth is controlled by how high out of the table or how low it is. So by interchanging some of these bearings, I can make something with a rabbet’s width of a 16th of an inch all the way up to almost a half an inch. So that’s one way to do it.
A second way to do it is by using just a straight bit; I’ve got one on the table. This particular one works as a straight bit in the table and the way that you gain the rabbet’s width is by moving the fence in or out in that bit and the rabbet steps is by raising or lowering it, but I’d like to do is set this up and we’ll run that board through and show you cutting a rabbet using a straight bit on your router table.
To cut this rabbet, I’ve lowered the bit in the table here to about a quarter of an inch above the table surface and I move the fence to within about three eighths of an inch of the front of that bit.
So I’m cutting a three eighths by quarter inch rabbet. I want to make sure though that I never moved that fence too far back that the cut actually gets beyond the centerline of that bit. It makes the bit very unstable and the cut very unstable and a lot less safe.
So what I’ve got this set up just before the center of the bit, I’ve got the bit raised about a quarter of an inch. I’ll make one pass across the face of this.
You’ll see how nicely a router table and a relatively short piece cut a beautiful rabbet. A very nice, clean, even rabbet down there done with a router bit on the router table. And again that’s a straight bit, provides a really nice clean edge.
How To Cut A Rabbet, Groove And Dado Joint With A Handheld Router.
Alright, now let’s talk about doing some dadoes and grooves. But to be honest, the router table is probably not the best place for that, just not quite enough depth behind the router fence to do it. This is a hand router operation so let’s go over to the workbench for that. I want to show you how you can put a rabbet on the edge of a board by using handheld router
I’m using the same bit that we talked about a minute ago on the router table. And this is it in the router here. Now, it’s got a bearing on it, the bearing will right up against this edge and automatically control how deep it goes. And I’ve set the depth in there to give me a relatively shallow quarter inch rabbet.
So I’ll make one pass across the front of this, you’ll see we’re talking about. Whenever you’re routing, especially with a hand router, you’re always going left to right, so that’s the idea here too. So the handheld router, here is that same rabbet at the end of a board.
Again, we could change the bearings on this and if you bought a bit like that, you can change the bearings and make that a little bit deeper. But let’s just say you’ve made that rabbet and you find out it’s not deep enough, we can now change by using an edge guide and a straight bit to make this rabbet even a little deeper still.
Here’s how that works. Now that I’ve routed the rabbet on the end of that board, I’ve decided that I want to just a little bit wider. I can do that by using an edge guide and a straight bit on my router and I’ve done that here.
So the edge guide slides to the base of the router and actually controls how far into that cut that bits going to go and I’ve set it just to make that rabbet just a little bit wider. So you’ll see what I’m talking about here when I started up.
Now the second cut I made with that bit is actually just a little bit wider than the first, actually works out really well and I can keep going back with that as much as I want to make that wider and wider and wider.
Now I guess if you wanted to keep going you could actually put a groove or a dado using that same edge guide, but you’re limited by how far that edge guide will go. So much better bet we have here with a small easy to make jig that makes dadoes and grooves easy on any board. Let me show you how that one works.
To put a groove or a dado in this board that’s too far in or too far from the edge for an edge guide. One of the things we can do is just place a straight edge on there and clamp it on either side. Many of you have done that. But there’s a much better system and it’s a much simpler jig. And once you use it you’ll probably want to make sure that you have them in your shop.
What we’re going to do is take the shelf that we’re planning on inserting and using that as our spacer. We can get the exact size of this. So what I’m going to do is I’m going to use two jigs like this, they have a little cleat on one end.
They’re about an inch thick, you may have to build yours up, make them with a couple of pieces of half inch plywood or like we did a quarter inch plywood and three quarter inch piece of MDF. And we make two of these, and they’ve got a little stop on the back end.
The key to this to make sure that the stop is even at the back and perfectly perpendicular to the sides. That’s important and the idea is we’re going to use those to frame the width of this shelf. So I’ve got one facing in this direction with the cleat on the top and the other one with the cleat on the bottom.
And once I’ve pinched that shelf in there, and I clamp those in and take this out, the space that’s left inside there is exactly the width of the shelf. Now what makes this system work really well is a bearing bit like this. It’s got a straight cutter and a bearing on it.
This particular one is called a top bearing. This is the bearing here or rise above the cutter. This is going to be on the router and what happens is this little bearing rides against the edge of that jig. So the jig controls how far that opening spaced is and because you’ve set it with the shelf means that it should be perfect and we’re going to run down one side.
And if it’s narrow enough bit, we’re going to run up the backside and that’ll create the perfect inset or groove for the shelf that you’re planning on putting in there.
The other thing is that we’ve assembled these with these little blocks at the end. And what I’d like you to do is make sure that the block on the left hand side goes at the top of that groove or potential groove and the other one goes at the bottom and there’s a reason for it.
Whenever you route, your routing from left to right, so in this case, we’re going to start up the left side of this jig and route up to the top, then crossover and route back.
If I leave the little cleat on the edge of this, as the router bit goes past the top, there’ll be no chip out there because the cleat is going to keep that chip out from happening. And as I come around from the back side and come through the front, I’ll eliminate the chip out there because again, this has got a block that will stop that also.
So the idea is I’m going to use my pattern bit that’s a top bearing bit in the router. Here is the shelf we’re planning on using and its width. I’ve got these up on standoffs and a couple of clamps on these to hold it; we’ll fix the position of that groove.
Press these up as firmly as it’s going to take to hold that shelf in there well because you want the groove to be just as tight.
Now I’ve got the perfect groove. Now it’s time to route it.
There is how your shelf fits in and opening. It works really well. Easy for you to use, no chip out at the front or the back of that cut because of the way we set the edges cleats out and I think you’ll find that that check works well. It’s easy to build, easy to use. You need a couple!