Mortise-and-tenon joinery is one of the most reliable ways to connect two pieces of wood. Whether you're building a table, cabinet, chair, or workbench, this traditional woodworking joint provides strength and stability without relying on mechanical fasteners.
And while there are plenty of specialized mortising machines and elaborate jigs available, you don't necessarily need them to get accurate results.
In fact, you can make a well-fitting mortise-and-tenon joint using tools you probably already have in your workshop: a drill press, table saw, and a sharp chisel.
The process comes down to three basic steps. First, drill and clean up the mortise. Next, cut the tenon shoulders. Finally, trim the tenon cheeks until you have a snug fit.
Here's how it works.
What Is a Mortise-and-Tenon Joint?
A mortise-and-tenon joint connects two pieces of wood by fitting a projecting tongue, called the tenon, into a matching opening, called the mortise.
The mortise is typically cut into one workpiece, while the tenon is formed on the end of the adjoining piece. When properly sized, the two parts fit together with enough surface area for a strong glue joint.
You'll find mortise-and-tenon joinery in everything from traditional furniture to heavy-duty workbenches.
The key to success is making the mortise and tenon fit one another. Rather than trying to cut both parts to exact measurements independently, it's often easier to establish the mortise first and then size the tenon to fit.
That's the approach we'll use here.
Step 1: Drill and Clean Up the Mortise
Start by laying out the mortise on your workpiece. Mark its width, length, and location, making sure it's centered where the adjoining piece will connect. For this example, we're cutting a 3/8"-wide mortise using a 3/8"-diameter drill bit.
Set up your drill press with a fence to position the workpiece. Adjust the fence so the bit is centered on the mortise layout, then set the depth stop to establish the mortise depth. Clamp the workpiece securely before drilling.
Drill a series of overlapping holes along the length of the mortise, removing the bulk of the waste. Then use a sharp chisel to clean up the sides and straighten the walls. Don't worry about squaring up the ends of the mortise. You can leave them rounded and shape the tenon to match later.
Woodsmith Tip: Use the drill press fence to keep all the holes aligned. If you're making several identical joints, the same setup helps maintain consistent mortise locations from one workpiece to the next.
Step 2: Cut the Tenon Shoulders
With the mortise complete, it's time to cut the matching tenon. Start by marking the tenon length on the end of the adjoining workpiece. The tenon should be slightly shorter than the mortise depth to leave a little room for excess glue.
Set the fence on your table saw to establish the tenon length, using the outside of the blade as your reference. Then raise the blade to the desired shoulder depth. With the workpiece supported by the miter gauge, make a shoulder cut on both faces.
Next, remove the waste between the shoulder and the end of the board. Make multiple passes over the blade, gradually cutting away the material to form the tenon. Repeat the process on the opposite face, leaving the tenon slightly oversized so you can fine-tune its fit.
Woodsmith Tip: Use the same fence setting when cutting the shoulders on all your matching parts. This keeps the tenon lengths consistent and helps the adjoining pieces align during assembly.
Step 3: Trim the Tenon to Fit the Mortise
The final step is to adjust the tenon until it fits snugly into the mortise. Rather than guessing at the final dimensions, use a scrap piece that's the same thickness as your workpiece to dial in the table saw setup.
Make passes over both faces of the scrap, gradually raising the blade until the remaining tenon matches the width of the mortise. Once you've established the correct blade height, use the same setup to trim the cheeks of the actual tenon.
Next, trim the width of the tenon to match the mortise length. Since the mortise was made with a drill bit, its ends are rounded. Use a file to round over the corners of the tenon so it seats fully in the opening.
Test the fit before applying glue. The tenon should slide into the mortise with firm hand pressure, and the shoulders should seat tightly against the adjoining workpiece without gaps. If the joint is too tight, remove a little more material and test it again.
Tips for Getting a Better Mortise-and-Tenon Fit
A good mortise-and-tenon joint depends on accuracy, but you don't need to achieve the final dimensions in a single cut. Taking a few extra minutes to check your setup and test the fit can make a big difference.
Always cut the mortise first and use it as the reference for sizing the tenon. Leave the tenon slightly oversized during the initial cuts, then gradually remove material until you achieve a snug fit. It's much easier to remove a little more wood than to correct a tenon that's been cut too thin.
Pay particular attention to the shoulders. They should sit flush against the adjoining workpiece without gaps. If the shoulders are uneven, the joint may not close properly, even if the tenon itself fits the mortise.
Finally, avoid making the joint excessively tight. A tenon that requires heavy pounding can split the mortised workpiece, especially after glue is applied. Aim for a firm fit that allows the pieces to come together with hand pressure.
Do You Need a Mortising Machine or Router Jig?
Not necessarily.
For occasional mortise-and-tenon joints, the drill press and table saw method described here is a practical option. It uses common workshop tools and doesn't require building a dedicated jig.
However, if you're cutting dozens of identical mortises, working with larger joinery, or looking for greater repeatability, a specialized setup can make the process more efficient.
A plunge router with a shop-made mortising jig, for example, can produce clean, consistent mortises with less chisel work.
For a closer look at those options, check out our other Woodsmith mortising techniques and shop-made jigs.
More Ways to Cut Accurate Mortises
Whether you're making a single joint or preparing the joinery for an entire furniture project, there's more than one way to get the job done.
Explore these related Woodsmith techniques:
4 Ways to Cut a Perfect Mortise: Compare different mortising methods and find the approach that works for your workshop.
Perfect Mortises with a Precision Plunge Router Jig: Learn how a shop-made jig helps guide a plunge router for accurate, repeatable mortises.
Simple Router Mortising Jig: Build a straightforward router jig for cutting mortises without investing in a dedicated machine.
With a few basic techniques and a little practice, you'll be ready to put this classic woodworking joint to work in your next project.
