How to Cut a Rock-Solid T-Bridle Joint
One of the first joints I learned to cut during my City & Guilds of London training was the T-bridle, which we used for the leg-to-rail connection on a modern end table, one of the projects that made up the curriculum. Like other variants of the bridle joint, this one is often used for table bases and benches. You can see an especially elegant example of this joint here.
The T-bridle makes a rock-solid joint by integrally interlocking the two parts. A well fitted joint will hold together firmly even without glue (though I would not recommend leaving it unglued in your final assembly, as shrinkage could loosen the joint over time). It’s a champ at resisting racking. And depending on how you work it into your design, it can provide a subtle decorative enhancement.
You can use this joint with parts that are the same thickness as each other or in cases where the legs are thicker than the rail. For parts that are the same thickness, make the notch in the leg 1/3 of the rail’s width for maximum strength. If the leg is thicker than the rail, you can leave the notched part of the rail a little thicker. (Note: For pieces where the rail is considerably thinner than the leg, it’s more typical simply to notch the leg to house the rail’s entire thickness; i.e., the rail in such cases is not notched to accept the leg.)
1. Mark the width of the leg onto the rail for the bridle joint
Make sure the leg is cleaned up so you don’t have to remove material later, which would alter the fit. All parts must be square. I make my marks in pencil, hugging the edge as close as possible. Extend the lines around all sides.
2. Mark and cut the notch that makes this a bridle joint on the leg
You can use a mortise gauge or a marking gauge.
Cut the cheeks of the notch with a backsaw, a bandsaw with a fine tooth blade, or on a table saw. I used a table saw with a tenon jig.
Clean out the waste on the saw or by hand, with a chisel. Because my saw couldn’t cut deep enough for this particular joint, I made the rest of the cut by hand.
4. Mark and cut the notch on the rail
Reset the gauge as needed* to transfer the notch on the rail. Score the shoulders with a knife and make a V with a chisel, then saw with a backsaw. Alternatively, you can cut these using a miter gauge on the table saw, cleaning out the waste by moving from one side to another, as I did. Clean up any remaining blade marks by paring down to your gauge lines with a sharp chisel.
*If your rail and leg are the same thickness and you reference from the face side each time, you won’t need to reset the gauge. If your leg is thicker than the rail, you will have to reset the gauge to take that additional thickness into account.
5. Test the fit
The fit should be snug. But beware of making it too tight, which could cause the leg to split.
This joint offers a lot of surface area for gluing, which reinforces the joint’s strength. If the joint is well cut you shouldn’t even need a clamp, other than perhaps to pull the rail fully into the notch in the leg. Check with a framing square or by comparing diagonals, depending on the type of construction you’re making.
To make this joint even more bombproof you could add a drawbored peg.
The bench below is one of my current commissions. The front rail is joined to the leg assembly by means of T-bridle joints.