Mortise and tenon joints are used to connect two boards together at (typically) 90°.

The mortise is a rectangular hole which the tenon fits into. It’s pretty biological, if you think about it (don’t).

You’ll most often see mortises used in the legs of furniture, with the tenons cut on the stretchers, aprons, or panel sides.

The two most common types are:

• Stopped Mortise: The mortise doesn’t go all the way through the board, and the tenon is completely hidden
• Through Mortise: The mortise goes all the way through the board, and the end of the tenon is exposed

It’s a super strong joint because the tenon is supported on all four sides — and when laid out correctly, there’s plenty of long grain to long grain glue contact.

Mortises are the most time consuming part of this joint.

Pretty much any way you do it, you’ll have to use a chisel at some point. So be sure to brush up on good chisel technique.

A mortising chisel is the go-to tool for hand cut mortises — and their width often determines the width of the mortise.

Honestly though, you don’t need one. They’re great, but I personally just use my bench chisels.

The most important thing is to use a marking knife or marking gauge for your layout lines.

It gives you a physical reference for your chisels — and improves your accuracy a ton.

But don’t start in your marking knife lines. First, clear out all the waste you can, staying away from your lines.

Cut the remaining waste in half until there’s no other option than to set your chisel in the knife lines and finish the edges — but avoid the corners.

When the sides are mostly done, use them as a reference to swivel your chisel down into the corners for a perfectly clean cut.

For through mortises, don’t chisel all the way through. Cut halfway through, then flip the board and work from the other side.

This will keep you from blowing out your lines on the opposite face.

Of course, the real key to success is lots and lots (and lots) of practice. No one’s ever hand-cut a perfect mortise on their first try.

Keep at it, and read this for more tips on chisel technique.

To clear most of the waste in one fell swoop, I first take my mortises to the drill press.

Use a forstner bit that’s slightly smaller than your mortise, and drill down to the appropriate depth. You might have to drill multiple holes for longer mortises.

If it’s a through mortise, use a backer board to avoid tearout.

Once that’s done, use a chisel to clean up the edges as described above.

This is my most used mortise strategy, and it saves a ton of time.

You can also use a plunge base router in place of a drill press. Just make sure it’s steady and use an up-cut spiral bit to clear sawdust efficiently.

Cutting mortises with a router is quick and accurate — but takes some careful set up.

Where possible, I like to use a router bit that’s the full width of my mortise. That way, I get perfect edges in a single pass.

You’ll need a good edge guide or jig to keep your cut lined up, and consider clamping down some boards as temporary stop blocks for your top and bottom edges.

Then just square off the ends with a chisel.

Tenons are a lot quicker to cut than mortises — but the trick is making sure they match your mortises (which I’ll give a few tips on later).

This is the slowest way to cut a tenon — but slow isn’t always bad.

I recommend making your initial cuts slightly away from your lines, then coming back with a chisel to clean them up.

Start by cutting the cheeks down to the shoulder line. Work from both sides so you only have to focus on two lines at a time. Then use those kerfs as a guide to clear the waste in the middle.

Read more about sawing technique here.

Once that’s done, cut the shoulders. Use your sharpest chisels, shoulder planes, or router plane to take the cheeks and shoulders right down to the line.

FYI: We’re going to launch a presale soon for our very own router plane. It’s honestly going to be the best on the market — so keep an eye out.

This is my favorite way to cut tenons.

It works best if you install a dado stack or a blade with flat top grind (FTG) teeth.

They’ll give you flat cheeks on the tenon, unlike ATB blades which will leave little bumps of waste. You can read more about table saw blades here.

After setting the blade at the right height (use your marking knife lines as a guide), I use a stop block on my crosscut sled to make sure I don’t cut past the shoulder line.

From there, it’s just taking multiple passes until you’ve cleared away all the waste.

The tips below aren’t rules — you can cut mortises and tenons any way you like.

But they will help you get better results right off the bat.

When laying out a mortise and tenon, a lot of woodworkers think in thirds.

That means the width of your mortise will be one third the width of your board.

It leaves plenty of material on the sides of the mortise to hold the tenon in place without risk of it breaking through.

This isn’t an issue if your mortise board is really wide. But on narrower boards, you don’t want those mortise cheeks paper thin.

On a board standing vertically, the top and bottom walls of a mortise are end grain — which is a notoriously bad gluing surface.

But the cheeks provide a long grain to long grain gluing surface with the tenons, which is super strong.

Where you can, maximize the long grain contact in your joint. That might mean mortises that are taller than they are wide — or even multiple mortises.

Say you’re attaching a shelf to a cabinet side. You’ll actually get a stronger glue joint by doing multiple mortises instead of one long one.

It’s nothing to get your pantalones in a bunch about. A tight fitting mortise and tenon will always be a strong joint.

But if you want it the strongest it can possibly be, pay attention to the long grain contact.

Cutting the mortise first has one major advantage: Tenons are a lot easier to adjust than mortises.

Use a pencil to tentatively layout the edges of your mortise. Once you’re happy, score your final lines with a marking knife or marking gauge.

If you’re cutting a through mortise, reference the same side for corresponding edges.

For example, rest the fence of your marking gauge against the right side of the board to mark the right side of the mortise.

Then flip the board over and reference the same edge (now the left side) to mark the left edge of the mortise. This ensures your through mortise will line up perfectly on both sides.

Here’s a simple equation to help layout your tenon.

(Thickness of tenon board – Width of mortise) ÷ 2 = Distance to set marking gauge

For example, say your mortise is 1 inch wide and your tenon board is 1 ½ inches thick.

Subtract the width of the mortise from the thickness of the tenon board and you get ½ inch.

Divide that by 2 to get ¼ inch.

Now use calipers or a square to set your marking gauge to cut ¼ inch from its fence. Mark the cheeks on your tenon, and bingo.

You can use a similar formula to figure out the height of your tenon. Just use the tenon board width and mortise height as your first two variables.

This method can be super accurate, but it’s still best to test fit your tenon before cutting the entire thing.

Which takes us to our next tip…

Even though your tenon lines are marked out, don’t cut to that line just yet.

Set the height of your table saw blade so it’s a hair lower than the line. Then cut two opposite faces at the end of the tenon.

Test the part of the tenon you cut in your mortise to see how it fits. If it’s too tight, raise the blade slightly and make another cut on each side.

Once the test fit feels right, you can clear out the rest of the waste down to the shoulder line.

For through mortises, do the test fit on the show face of the mortise. Since that’s where the tenon will be visible, that’s where you want precision.

The back will be hidden by the shoulder of a tenon anyway. So it’s ok if it’s not perfect.

Test fitting your tenon like this takes a little more time — but will really help you get a perfect fit.

For through mortises, it’s never a bad idea to plan for the tenons to sit proud.

Then just trim the end with a flush cut saw and clean it up with a hand plane for a perfectly flush show face.

You can even just leave the tenons proud. Chamfer or round over the edges with a chisel, and you’ll have a nice design element.

There are a ton of ways to add extra strength and beauty to your mortise and tenon joints.

I covered two of my favorite variations in my Joint of the Week series.

One is a tusked mortise and tenon that looks amazing and hardly needs glue.

The other is a wedged mortise and tenon that provides a great opportunity to play with contrasting wood colors and add extra detail to your piece.

Don’t be afraid to try different techniques and challenge yourself with new joinery. Your first few attempts might be dismal (I know mine were) — but you’ll get better over time.

If you enjoy joinery, learning to cut mortise and tenon joints is essential.

They’re strong, useful, and super versatile — and mastering them gives you the skills to cut almost any other joint out there.

And don’t stress over perfection. Even mortise and tenon joints with a couple gaps will be rock solid. So go easy on yourself and enjoy the process. source

To test a chisel’s sharpness, use the Paper Test.

Hold a piece of paper in one hand then try to slice off strips with the cutting edge of your chisel.

The blade should slice effortlessly and leave clean edges, like a pair of scissors.

If the paper is tearing, it’s time to sharpen.

You may have seen people test chisels by shaving off arm hairs. I don’t recommend this — and you better believe that’s based on personal experience.

A piece of paper costs a lot less than a Band-Aid or stitches.

Sharpening frequency depends on how often you use your chisels, what materials you cut, and the type of cuts you make.

Chopping out a mortise in maple will sharp chisels a lot faster with a sharp chisel.

My strategy is to do the Paper Test every time I’m about to use my chisels.

If it’s mostly slicing but tearing the paper a little, I’ll give the chisel a quick strop.

Stropping really extends the time between full on sharpenings. I can get away with stropping 7 or 8 times before needing to re-hone the secondary bevel (sometimes a lot more if I’m lazy).

Do the Paper Test before every chiseling session and you’ll know whether it’s time to sharpen.

• Sharpening stones and lubricant: You’ll need a set of water stones, diamond stones, or lapping sandpaper. All of them work great and have their respective pros and cons.
• Honing guide: A honing guide makes consistent sharpening easy — which is all that really matters. You can of course sharpen freehand, but the learning curve is steep.
• Strop and polishing compound: Stropping is the key to getting a razor sharp edge — and can extend the time between full on sharpenings.
• Non-slip work surface: Having a non-slip work surface keeps your stones from sliding all over the place — and prevents inadvertent water spills (trust me, I know). Here’s what I use.

 

Diamond Stones

 

Water stones, diamond stones, and lapping sandpaper all work great for sharpening. Which to choose depends on preference.

Water stones cut the fastest of the three mentioned and are fairly affordable, but need to be flattened before use (you’ll need a dedicated Dimaond Stone or a  Flattering stone for this). Lubricate them with water. Water Stones have a smaller grit for the sharpest possible finishing with a strope

Diamond stones always stay flat and require almost no maintenance, but are generally more expensive. Lubricate with water, Windex, or non-hardening oils (I prefer Windex). Diamond Stones can be used to flatten the wet stones. Diamond stones have a larger grit, if you can finish with water stones and a strope

Lapping sandpaper mounted on a flat surface has a super low start up cost, but won’t last as long as diamond or water stones. You can also only stroke backwards (mind out of the gutter). Lubricate with water.

 

There are 3 main steps of the sharpening process I follow:

• Grinding and Flattening: Grinding a fresh 25° primary bevel and flattening the back of the chisel.
• Honing and Lapping: Creating the 30° micro-bevel and removing any burrs.
• Stropping: Polishing and fine tuning a razor sharp edge on the tip of a chisel.

Re-grinding is something you do NOT need to do often — and certainly not on new chisels.

It’s only necessary when honing the secondary bevel stops being efficient (i.e. it’s bigger than the primary bevel). Or if your chisel’s absolutely mangled.

90% of the time, you only need to hone the micro-bevel and lap the bottom.

And even still, you can put off honing for a while by stropping consistently (some people disagree, but it works for me).

Because it’s so rarely needed, I’m going to skip details on the grinding stage. It’s essentially the same as honing the micro-bevel, only you do it at a 25° angle.

To save time, I use a wheel grinder. But with enough time and elbow grease, you can definitely grind by hand.

Now onto the meat and potatoes.

Set up your chisel in a honing guide so it sits at 30°. Use a digital angle guide, bevel gauge, or set-up block to get it close.

You can even just set it so the primary bevel is flat, then pull the chisel back a hair until the back of the primary bevel raises slightly.

Do your best to make sure the chisel is square to the honing guide. No biggie if it’s not perfectly square, but try and get it close.

Lubricate a semi-coarse sharpening stone (around 1000 grit) and set the wheel of the honing guide on it first. Then lower the tip of the chisel onto the stone.

Never start by putting the cutting edge down first, as this can dull the blade or dig into your stone.

Put even pressure on the chisel blade with your fingers and pull it back across the stone. Lift the tip of the chisel, roll the guide forward, and repeat.

Once you’ve done 3-5 back strokes, you can push and pull the chisel edge over the stone (except on lapping sandpaper — only move back on this).

Continue making strokes until you feel a small burr on the back of the chisel.

A burr is a nearly invisible sliver of metal that spans the width of your chisel. Though hard to see, you can feel the small ridge and it makes a clicking sound when you run a fingernail over it.

Think of it as a microscopic speed bump across the back of your chisel that is created where the metal gets so thin at the tip that it folds over.

Once you feel that burr you can continue through the higher grits until you reach your finest stone. Go to as high of a grit as you like. But 6,000 or 8,000 is probably plenty.

Now it’s time to lap the back.

Remove the chisel from the honing guide. You’ll be able to feel a small burr on the back edge of the chisel’s tip. Time to take that off.

Set the back of the chisel onto your coarse stone, but don’t start with the tip (I said stop). You can even set it down so the tip overhangs the stone to make sure.

Drag the chisel back onto the stone making sure to keep even pressure. I recommend keeping your fingers only on the steel. Holding the handle can make you inadvertently raise or lower it.

After pulling back for a few strokes, move back and forth over the stone.

Again, you’re looking for fresh scratch marks. But don’t stress if they’re not appearing over the entire back of the chisel.

It really only matters on the tip and edges. If there’s a hollow in the middle that’s not taking scratches, it may actually be by design.

As long as scratch marks appear on the tip and edges of the chisel back, you’re good.

If you’re a perfectionist, you can lap the entire back of the chisel flat. But honestly, I usually only worry about the first inch and half from the tip. You’ll rarely need more.

Repeat this process on your higher grit stones until you’ve got a nicely polished back.

At this point, your chisel should be razor sharp. But to get it where it can slice through oak like butter…

Time to pull out the old horse’s butt.

Stropping takes the sharpness of your chisel to the next level. I didn’t really believe it until I used one — but man, does it make a difference.

Put a healthy amount of honing compound on your strop. It doesn’t need to be caked on, just solidly covered.

Once you have a decent amount on there, I add more only about every 5-10 times I strop.

Place the tip of your chisel on the strop bevel side down. Lift the back until the very tip is flat on the leather (you’ll see the shadow disappear).

Lock your wrists in place and drag the chisel back over the strop. Do your best to keep the chisel from tilting out of position while putting decent pressure on the edge.

Repeat this about 30 or so times, then switch to the back.

Use light pressure when stropping the back. You’re just trying to get rid of any last remnants of a burr, and don’t want the cutting edge digging into the leather.

Test the edge on a piece of paper — and I’m sure you’ll be more than happy with the results.

Dry the chisel off completely with a clean cloth.

Once dry, coat the steel with a thin layer of paste wax or 3-in-1 oil. This will keep it from rusting and help it slide more easily over surfaces.

Rinse off your sharpening stones, pat them dry, and you’re ready to start chiseling.

People make a big deal out of sharpening. But it doesn’t need to be.

As long as your chisels slice through paper like a pair of scissors — you’re absolutely fine.

Check often, strop frequently, and enjoy the feeling of a razor sharp edge (on wood, you masochist). source