How to Make Stub Tenon & Groove Joints with a Router Table

Stub tenon and groove joinery is a cornerstone of traditional Craftsman-style furniture. It's a straightforward way to connect rails and stiles in cabinet doors, frame-and-panel assemblies, and other woodworking projects. The joint is relatively simple to make, but getting clean shoulders and a snug fit is essential for a professional-looking result.

When I build a project that uses stub tenons, I usually turn to the table saw to cut the grooves and form the tenons. Lately, though, I've been using my router table more often. I've found that it produces flat-bottomed grooves, smooth tenon cheeks, and clean joint lines with relatively little setup.

The process starts by routing the grooves in the stiles and then sizing the tenons on the rails to fit. A coping sled makes the cross-grain tenon cuts safer and more consistent, especially when working with narrow parts.

Here's how I use the router table to make accurate stub tenon and groove joints.

What Is a Stub Tenon and Groove Joint?

A stub tenon is a short projection formed on the end of a rail. It fits into a matching groove cut along the edge of a stile, creating a simple mechanical connection between the two parts.

Unlike a traditional mortise-and-tenon joint, which uses a deeper mortise cut into the workpiece, a stub tenon typically fits into a continuous groove. This makes the joint particularly useful for frame-and-panel construction, where the same groove can also capture the edge of a floating panel.

For many cabinet doors and smaller furniture components, a 1/4"-long tenon is a practical starting point. The exact dimensions depend on the project, stock thickness, and the strength required.

The advantage of using a router table is that you can cut the grooves and tenons with controlled, repeatable setups. Once the fence and bit height are dialed in, it's easy to produce matching joints for an entire project.

Step 1: Choose a Router Bit for Cutting the Grooves

I prefer to cut the grooves first and then size the stub tenons to fit. This eliminates the need to match two independent setups to a predetermined dimension. Instead, the completed groove becomes the reference for the tenon thickness.

The first decision is which router bit to use. A straight bit and a slot-cutting bit can both produce accurate grooves, but each has its advantages.

Straight and Spiral Router Bits

A straight bit is a simple choice for cutting grooves. For most of my frame-and-panel projects, I use a 1/4"-wide groove, so a 1/4" straight bit is a natural fit.

I often reach for a spiral upcut bit instead of a conventional straight bit. The spiral cutting edges help evacuate chips from the groove, reducing buildup during the cut. When the bit is mounted in a router table, the upcut geometry directs chips downward toward the router, so good dust collection beneath the table is helpful.

A straight or spiral bit works well for relatively shallow grooves. For deeper cuts, it's usually better to remove the waste in multiple passes rather than trying to reach the full depth at once.

Slot-Cutting Router Bits

A slot-cutting bit is another option. It works much like a small dado blade for the router table, using a horizontal cutter to form a groove along the edge of a workpiece.

Some slot-cutting systems allow you to combine cutters or select different cutter widths to produce a specific groove size. Depending on the bit and the material, a slot cutter may also allow you to form a deeper groove without making as many passes.

The trade-off is cost. A slot-cutting system can be more expensive than a standard straight or spiral bit, particularly if you need several cutter widths.

Either approach works well. For a typical 1/4"-wide groove, I usually start with a sharp spiral bit.

Step 2: Set Up the Router Table for Centered Grooves

Once the bit is installed, the next step is setting the cutting depth and positioning the fence. The goal is a groove that's centered on the thickness of the workpiece and deep enough to accept the stub tenon without bottoming out.

I like to use a small setup rule to establish the bit height and fence location. A rule with an adjustable stop makes it easier to repeat the settings, but an ordinary combination square works, too.

With the router unplugged, set the bit projection for the desired groove depth. Then position the fence so the cutter is approximately centered on the edge of the workpiece. Lock the fence and make a test cut in a piece of scrap that's exactly the same thickness as your project parts.

Check the groove's position and depth. If it isn't centered, make a small fence adjustment and repeat the test until the groove is where you want it.

Use Two Passes for a Perfectly Centered Groove

There's a simple technique for centering a groove that doesn't depend on getting the fence position absolutely perfect.

Start with a router bit that's slightly narrower than the finished groove. Make the first pass with one face of the workpiece against the fence. Then turn the workpiece end for end so the opposite face bears against the fence and make a second pass.

The second cut removes a small amount of additional material, leaving a groove centered on the stock thickness. Because the bit is narrower than the finished groove, this technique produces a groove slightly wider than the cutter.

The important detail is to use a conventional feed direction on both passes. Keep the workpiece firmly against the fence and use featherboards or other appropriate hold-downs. Don't back-rout to make the second pass; climb cutting can cause the bit to grab and pull the workpiece unexpectedly.

Make a test groove first to confirm that the final width matches your intended tenon.

How Deep Should the Groove Be?

For a typical 1/4"-long stub tenon, I often make the groove approximately 3/8" deep. The extra depth provides clearance so the tenon doesn't bottom out during assembly.

If the ends of the joint will be visible, however, I prefer a closer fit. In that case, a groove that's approximately 1/32" deeper than the tenon can provide enough clearance without leaving an obvious gap.

The final dimensions should follow your project plans, particularly when the groove also holds a floating panel.

Step 3: Set Up the Router Table to Cut Stub Tenons

With the grooves complete, it's time to form the stub tenons on the ends of the rails.

A stub tenon is made by removing material from both faces of the rail, leaving a centered projection that fits the groove. Two settings control the finished joint: the fence position determines the tenon length, and the bit height determines its thickness.

Because you've already cut the grooves, you can use a grooved test piece to dial in both settings.

Switch to a Wider Router Bit

Before cutting the tenons, I replace the 1/4" groove-cutting bit with a wider bit. For a 1/4"-long tenon, a 1/2" straight bit is a useful choice because it can form the full length of the cheek in one pass.

A wider bit reduces the number of passes needed and helps produce a smooth, consistent surface. Use a sharp bit that's suitable for the operation and the cutting depth.

Use a Coping Sled for Accurate Cross-Grain Cuts

Routing across the grain introduces two challenges. The first is tearout as the bit exits the workpiece. The second is keeping a narrow rail firmly supported and square to the fence throughout the cut.

That's why I like using a router table coping sled. The sled holds the rail securely, keeps it square to the cutter, and provides a stable way to move the workpiece past the bit.

The Woodpeckers coping sled shown here is one option, but a shop-made version can work just as well. The important features are a secure clamp, a square reference fence, and a replaceable backer board to support the wood fibers at the end of the cut.

A coping sled also makes it easier to produce identical tenons when you're working on several rails for a cabinet door or furniture project.

Step 4: Dial In the Tenon Length and Thickness

Start by positioning the router table fence to establish the tenon length. For a typical 1/4"-long tenon, set the fence so the bit removes approximately 1/4" of material from the end of the rail.

Next, set the bit height to remove the material above and below the tenon. If you saved a grooved test piece, you can use it as a reference for the desired thickness.

Make a test cut on one face of a scrap rail, then flip it over and cut the opposite cheek. Try the resulting tenon in the groove.

You're looking for a snug fit that doesn't require excessive force. If the tenon is too thick, raise the bit slightly and make another test cut. Small adjustments are the key to avoiding a loose joint.

Once the test tenon fits correctly, lock the bit height and fence position. You're ready to cut the project parts.

Step 5: Rout the Stub Tenons on the Rails

With the setup complete, cutting the remaining tenons is straightforward.

Place the first rail in the coping sled, making sure it's seated firmly against the sled's reference fence and secured by the clamp. Slide the sled past the router bit to form the first tenon cheek.

Flip the rail over, secure it in the sled again, and make a second pass to form the opposite cheek. Repeat the process on the other end of the rail.

For consistent results, use the same reference surfaces and make sure each workpiece is fully seated before clamping it. If you're making several identical rails, cut all the corresponding cheeks using the same setup before changing anything.

Test the first completed tenon in its matching groove before routing the rest of the parts. If the fit is correct, you can complete the batch with confidence.

Adding Decorative Details to Stub Tenon Joinery

One reason I like stub tenon and groove joinery is its versatility. The same basic joint can be used for a simple, square-edged frame or incorporated into a more decorative cabinet door.

For Craftsman-style furniture, clean lines and straightforward proportions often look right at home. But you can also add a decorative profile to the inside edge of the frame or incorporate the joint into a more elaborate door design.

The important thing is to plan the joinery around the finished profile. Depending on the design, you may need to adjust the tenon length or cope the rail ends to match the stile profile.

A Simple, Repeatable Router Table Joint

Stub tenon and groove joinery is a practical choice for cabinet doors, frame-and-panel assemblies, and many Craftsman-style furniture projects. And while the table saw is a common way to make these joints, the router table offers an excellent alternative.

By cutting the grooves first, using a coping sled for the cross-grain cuts, and dialing in the tenon fit with a test piece, you can produce clean, consistent joints with relatively little setup.

The next time a project calls for stub tenons, give the router table a try. You may find it becomes your preferred method for this classic woodworking joint.

A special thanks to Woodpeckers for supplying the tools used to produce this article. Originally published in the Craftsman Furniture Projects Book.