HOW TO MAKE A MORTISE AND TENON JOINT WITH TRADITIONAL HAND TOOLS
This above video and article will simplify the process of cutting mortise and tenon joints with only a few traditional hand tools. With a little practice, you should be able to make a mortise and tenon joint in under 10 minutes! The video is a quick tutorial, but the below photos and article will clarify how to make a mortise & tenon joint in great detail:
ANATOMY OF A MORTISE AND TENON JOINT
WHAT ARE MORTISE AND TENON JOINTS USED FOR?
The mortise and tenon joint (also called “mortice” in Britain) is one of the strongest and most-widely used woodworking joints. It is an effective joint for holding together timber frame buildings, tables, chairs, doors, cabinets, windows, tool chests, clocks, and many, many other pieces of wooden furniture.
Because of it’s strength and many uses, the mortise and tenon joint is one of the very first woodworking joints that beginning woodworkers should learn. Even power tool woodworkers should learn the fundamentals of how to make a mortise and tenon joint with traditional hand tools!
SIMPLE HAND TOOLS YOU’LL NEED FOR CUTTING MORTISE AND TENON JOINTS
You don’t need many hand tools to make a traditional mortise and tenon joint. Here are the tools that I used (affiliate links):
- Brass wheel marking gauge (update: my new favorite)
- 6-Inch Combination Square
- Dovetail Saw
- Carcass Back Saw
- Joiner’s Mallet
- Pig Sticker Mortise Chisel
- Marking Knife
- Woodworking Clamps
- Wood Chisels
- My Workbench (Sjobergs 2500)
- Fine tip pencil
To make things easier for beginners I would recommend that you simply purchase an inexpensive pre-dimensioned stick of wood (e.g. poplar) for practicing. Make sure it’s square and straight and flat. Make several mortise and tenon joints, one after another, to really learn this method.
If you can only afford a single marking gauge (two middle gauges), that’s just fine. But you can speed things up with a dual marking gauge (below far right) or mortise gauge (below, far left):
STEP 1: LAYOUT THE TENON AND MORTISE BOARDS & MARK THE TENON’S SHOULDER LINE
The first step is to lay your boards out on your workbench and butt the tenon board up against the mortise board, so you can see exactly where you want them to join. Make some marks, and also make reference marks so you remember which faces are your reference faces (the faces that you will mark from with the marking gauges):
Next you will mark the shoulder line. The shoulder is where the tenon will stop against the mortise. Think of putting your head in a very small hole in the ground. Your head will go in, but your shoulders will stop at the top of the hole. Lay the tenon on top of the mortise and decide how deep you want it to go into the mortise.
If you’re making a common hidden tenon, layout your board so it stays back from of the end of the back of the mortise (see below)…around 1/4th of the way back and make a tick mark with your pencil on the tenon board.
What if you’re making a “through-tenon”? What’s a “through-tenon” anyway?
A through-tenon is a tenon that goes all the way through the mortise (see above). If you’re doing a through-tenon, then layout your board so that the tenon hangs out the other side a bit, and make a tick mark:
Now set a marking gauge on your tick mark and scribe the “shoulder line” all around the tenon. You can place the marking gauge on the end of the tenon.
STEP 2: MARK THE MORTISE AND TENON JOINT
The next step is to mark the tenon and the mortise boards with a marking gauge, a mortise gauge, or even better, a “Dual marking gauge”. A dual marking gauge will hold two measurements at once:
Not every board has the same thickness, so do all your marking from the same reference face to ensure the tenon will fit into the mortise. I like to mark my faces with some sort of squiggly mark:
First, set your mortise chisel on the top edge of your tenon board (centering it by eye) and set your marking gauge’s inner cutter to touch the edge of your mortise chisel:
Now that your inner marking gauge is set, scribe around the end of the tenon, from shoulder line to shoulder line:
Don’t change your marking gauge measurement yet. First transfer the line over to the inner edge of your mortise board and scribe it where your tenon will eventually go into the mortise hole:
Now go ahead and set the outer cutter to line up with the outer edge of the mortise chisel. Here is what both marking gauges should look like:
Then, just like before, scribe the outer tenon line, all around the top of the tenon, from shoulder line to shoulder line:
Keeping the same setting on your marking gauge, scribe the outer line on the mortise board:
The mortise and tenon should now look like this:
Note: if you’re making a “through-mortise” (like below) then mark both edges of the mortise.
If you have multiple mortise & tenon joints to build, then you now probably realize how much time will be saved by having a dual marking gauge. You won’t have to re-create the measurements over and over again. You’ll simply keep both measurements locked into your gauge.
STEP 3: CUT THE TENON CHEEKS
Now you will use a back saw to cut the tenon “cheeks”, or the faces of the tenon. You should use a backsaw with rip teeth because you’ll be cutting down with the grain. If you’re cutting a small tenon, like this, then a small dovetail saw will work fine:
But if you want to cut a larger tenon, then a rip tenon saw should be used:
Use a bench chisel to cut out a little trench to provide your saw with a track for starting into the cut. It really helps with stability and straight cutting:
Your saw will rest against the trench wall:
Star the cut at a 45 degree angle, then start sawing horizontal, across the top end grain, staying a hair to the waste side of your line.
Once you’ve made a very shallow kerf on top of the board, move back to a 45 degree angle and continue sawing down to the baseline/shoulder line:
Flip your tenon piece around in the vice and saw from the other side, but in your new kerf that you just created on top of the board. The kerf that you already created will guide your saw downward in an accurate fashion. You can saw horizontally this time. Just make sure you stop before you reach the baseline/shoulder line:
Repeat the same steps on the other line that you marked on the tenon, then you’ll have two saw cuts / kerfs running down the tenon:
Whew! Sorry if that was confusing, but the above video should clarify any mystification. The rest is pretty simple now:
STEP 4: CUT THE TENON CHEEKS & SHOULDERS
Now we move on to cutting the tenon cheeks and shoulders. Since some of these cuts are across the grain, ideally you should use a different backsaw with crosscut teeth: a carcass backsaw:
If you can’t afford another back saw yet, you can indeed use your dovetail saw (with rip teeth), but you won’t have as clean of a cut and the cutting will be harder. You’ll have to clean it up with a chisel.
Moving on. Secure your tenon piece against a bench hook (or with a hold fast or in your vice some how), and deepen your shoulder line with a wide bench chisel and wooden mallet. Place the chisel precisely in your shoulder line (you previously created it with a marking gauge…remember?) One or two medium strokes with the mallet is deep enough. Make sure your chisel’s bevel is facing the tenon, like this:
Now use your wide bench chisel to create a little angled trench to guide your carcass saw:
This will allow your backsaw to rest against the shoulder, and will provide a more accurate guide when sawing downward. Now place your cross cut carcass saw in that trench and saw straight down:
Be extra careful to not saw too far. Slowly “creep” up to the line. If you cut your long rip cuts deep enough, then the waste piece should simply pop off the cheek like this:
But often you need to go back into your long rip cuts and “creep” down a bit with a dovetail saw:
Repeat on the other side. Now your tenon should look like this:
If your sawing wasn’t perfect (don’t be embarrassed) you can straighten up your tenon “cheeks” and “shoulders” with your bench chisel (and a shoulder plane, if you like):
STEP 5: CUT THE TENON SIDES OFF
Use your square to draw vertical lines down both sides of your tenons and cut off a tad from each side with your dovetail saw:
Use a cross cut carcass back saw to cut the side shoulder:
These measurements aren’t critical because you will scribe the mortise width from whatever size you just trimmed your tenon to…so it’ll fit tight.
STEP 6: MARK THE MORTISE
Your tenon should now look like this:
Lay your freshly finished tenon on your mortise and use a marking knife to make a tick mark at the edges of your tenon. Use your square and marking knife to scribe a line from the tick mark so that you have the full outline of your mortise:
Above you’ll notice that the crossed out area is where you will chop the mortise out with a mortising chisel.
STEP 7: CHOP THE MORTISE
Now it’s time to use your mortise chisel (or “mortice” chisel for my British friends) for chopping your mortise. I’ve seen several methods for chopping a mortise, but I’ll sharing my favorite method, which I learned in a class from Roy Underhill:
I like to setup my mortise chopping using a traditional method from England:
The mortise board is held stable between the clamp and a board (that I placed in a vice). The mortise board also sits on top of another board. Again, the squigly lines are where you’ll be chopping with your mortise chisel:
The width of your mortise lines should perfectly match your mortise chisel’s width. The sides of the mortise chisel will be barely touching your layout lines:
STOP! You do not want the chisel to initially chop on the end lines or else the force and expansion will lengthen your mortise opening, which would prevent a perfect fit for your tenon. So start chopping with your mortise chisel about 1/4″ inch away from each end of your mortise lines (see above). By “chop” I mean use your wooden mallet to hit the top of the mortise chisel. Chop straight downward. The angle of your mortise chisel’s bevel will cause the mortise chisel to go downward at an angle.
Keep chopping until you feel a lot of resistance, then pull the chisel straight out of the hole and “walk the chisel” down the edge of the board a little bit and chop downward again. Repeat this until you get within 1/4″ of the other end of your mortise and stop. I said stop! Just like the beginning, don’t chop on this line either…at least not yet. Flip the chisel around and repeat the chopping process going the other way, trying to start the chisel’s bevel on an unchopped spot. Your hole will get deeper and deeper.
Warnings: I try not to wiggle the chisel sideways when pulling it out of the mortise because I don’t want to alter the width of the hole. I also try not to use my mortise chisel to pry loose chips/chunks out of the mortise. Just keep chopping through those chips. If they really be come cumbersome, use an awl to remove the chips, but don’t ruin your mortise edges when prying.When you’ve marched back & forth down the mortise a couple times (and relieved the pressure) you can go ahead and place the mortise chisel on each line and drive straight down to create a clean mortise wall:
How do you know when to stop chopping? I use my combination square and adjust it’s length to match my tenon’s length:
Presto! You now have a perfect depth gauge…just stick it in the mortise to see how close you are to your final mortise depth:
When your combination square bottoms out, then it’s time to stop chopping.
Note: If you are chopping a through-tenon you would just repeat this marking & chopping process on the other side, and meet in the middle. You shouldn’t try to exit through one side…it’ll give a nasty exit wound. Alright, back to normal mortises:
Grab your 1/4″ bench chisel (or smaller) and pare/trim the inside edges of the mortise until they look vertical.
But don’t pare too much.
Try dry fitting your tenon first:
If your mortise walls look nice and vertical, then don’t pare anymore. Turn your attention to trimming the tenon instead. You can trim it using a shoulder plane or chisel. Just take small cuts then retest the fit.
But don’t let all this trimming & paring scare you. If you followed this tutorial, then you shouldn’t have to do much trimming, if any at all. A few light whacks of the mallet should seat the tenon in tightly. And the more mortise & tenon joints you make the faster you’ll get at it.
Congratulations! You can now cut the most important joint in traditional woodworking! Now choose a project that has a good number of mortise & tenon joints so you can reinforce what you just learned.