Locked Rabbets on a Table Saw
George VondriskaIf you want a simple but extremely strong way to build drawers or other types of boxes, the locked rabbet joint will be a good member to add to your joinery arsenal. The joint is simple to make because it uses careful placement of a rabbet and a dado that can be milled using a single setup on a table saw. Making rabbets on a table saw is straightforward as long as you have a good quality dado blade installed on an accurate table with a powerful motor.
When you want to make rabbets on a table saw, you will also have to mill dados on the corresponding member that match up exactly. If the fit is too tight, you will risk cracking the piece with the dado. If the fit is too loose, you might have a joint failure when the PVA glue is stressed through normal use. With a drawer, it is likely that this joint will be stressed, so be sure to invest the time as you mill your joinery.
The process consists of the following steps:
Install a dado blade. A good quality dado stack will be ideal when setting up to mill rabbets on a table saw. You will be better off using a stacked dado rather than a wobble style dado for this operation because you can produce a better-quality joint with a stacked dado.
Position the fence. Set the fence so that it positions the dado in the appropriate place.
Test cut. Run a test cut on both the rabbet and dado, and test the fit. Adjust the fence position to fine tune the fit.
After you’ve mastered this joint you will be able to put it to use on a set of kitchen cabinets, chest of drawers, or a variety of other projects.
A lock rabbet is a great joint to add to your arsenal and easy to do here on the table saw. What's great about them is mechanical interlock between the two parts. And once you get a couple of tips and tricks, which I'm about to show you, then they're really easy to set up and make. Now there's some geometry here to be aware of. Today, I'm using 3/4 inch stock.
So, 3/8, 3/8, 3/8, meaning, the dado head on the table saw is 3/8 wide. We're gonna set it to 3/8 deep. We're gonna set it so it's 3/8 from the fence. Now, test question, what if the material is 1/2 inch thick? 1/4, 1/4, 1/4, all right?
That's the relationship, is that the size of the cutter and all of those dimensions are half as big as what you're cutting. So, 3/8 dado head. Bar stock, my favorite way to gauge things. Saw unplugged, my favorite way to keep my fingers. Even with the top of the bar stock, there.
Then, 3/8 comes in here, where it fits between, the bar stock, just fits between the fence and the dado head. Then we do a test cut. Before we cut, take note of a couple of things. The insert in the table saw, the dado insert, is a zero clearance insert. So when you look at that closely, the hole in it is only as big as this particular dado head.
And the reason is that one of our pieces gets fed vertically like this. And if that hole in the insert was really, really wide, if it had been made by a 3/4 inch dado head, there'd be maybe an opportunity for a corner to dip in there and things to go bad. So you want a zero clearance insert in the table. And you want a tall fence on your saw. When we make this cut, we want to have plenty of real estate we can push against here so that this piece doesn't get tippy.
The cut is one part fed horizontally and one part fed vertically. And our test is, do they do this? Okay. That never happens. Meaning, they never fit on the first try.
You must be a very good group today. Think about what's going on here. Can we change the size of that dado? And we could change the size of the dado head, but really the answer is no, the dado head is set to 3/8. So this is not a variable.
This is a variable, because that dimension is controlled by the fence position. If this won't go in, if it's too big, joint's too tight, the fence has to be made closer to the dado head. If you do this, and it's too loose, then you have to move the fence further away from the dado head. And honestly, this is dumb luck, because it usually takes me two or three test cuts in order to get this fine tuned to a point where this is gonna work. The beauty of the 3/8, 3/8, 3/8 is that when we put this together, the components end up flush out here.
Okay, now, if you're doing this for drawer boxes, which is my most common application for this joint and it's my most common way to put drawers together, we need to pay attention to parts as parts and pieces as pieces. The horizontal component that we're cutting will be your door sides. The vertical component we're gonna cut will be the fronts and the backs, with the whole operation looking like this. Big thing to be careful about there, to watch out for, is make sure that we're keeping the same face referenced against the fence. And in this case, the same face referenced against the surface of the table saw, so both of those dados end up in the same face, with those tongues end up cut relative to the same face.
Really, really fast way to put things together. Another note, the parts with the tongues in the ends, those end up being your front and back. Mechanically that gives the drawer the most strength. A good joint to master. Easy to do on the table saw once you know, I think, these tips and tricks.
Give it a try, and I think you'll be using a lock rabbet on a regular basis.
Dead fiddly on a jobsite saw that won't/can't take a dado stack though, although it CAN be done - might be time for an upgrade...!
I was looking for the jointer bit you demonstrated and could not find it at my local woodworking store. What is the proper name for this bit and where can I find it?
What clamps are you using to hold the taller boards to your table saw fence?