How to Make a Castle Joint (3 Way Joint) an Easy Guide

Looking to elevate your woodworking skills with an impressive yet simple joint? Meet the castle joint, also known as the 3-way joint. This sturdy and versatile connection is perfect for beginners and a great way to practice and refine your joinery techniques.

In this guide, I’ll show you how to create a castle joint by hand, step by step. Whether you’re crafting furniture or just exploring new woodworking methods, this joint will become an essential part of your toolkit. Let’s dive in and start building!

How to Make a Castle Joint (3 Way Joint) an Easy Guide

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Take your time with this guide. When you’re ready to explore more, you can check out my subcategory Woodworking Tips for even more context and connections, or explore my category Woodworking Tools, Materials & Tips for an overview of everything in this area. But for now, let’s get started with the topic at hand!

Table of Contents

What is a castle joint?

The castle joint, also called the interlocking double bridal joint, can be simply explained as a three-way corner joint. This castle joint is a combination of the bridle joint and the cross lap joint.

Because there are 4 protrusions made on the vertical wood, this part resembles the battlements of a castle.
That is why they call this 3-way wood joint the castle joint.

A cross-shaped connection can be placed between these protrusions to make this three-way corner connection, or called the castle joint.

What is a castle joint used for?

Very often, the castle joint will be used in furniture making to join 3 pieces of wood together.
Such as the connection between the frame and the leg of a bed or a table.
But you can actually use this castle joint for any connection where you need to bring 3 pieces of wood together.

The condition is that the parts must be perpendicular to each other.

However, there is another requirement to use this castle joint, and that is that the wood used must have a certain thickness.
When the used wood is thinner, this castle joint will lose its strength and break quickly.
In this blog post, I will discuss this in more detail.

Does a castle joint need to be secured?

Well, that is one of the advantages of this kind of connection!

A castle joint should not need to be secured.
The shape of the 3 parts that slide into each other will ensure that they will hold each other and cannot fall apart.
Once the connection has been made, they form a tight and secure connection.

The great thing about the castle joint is that you can easily release this connection.
It is therefore a recommended connection for projects that need to be able to be disassembled from time to time.

If you want to increase the castle joint strength, you can always apply wood glue, CA glue, or epoxy glue between the pieces.
Remember that, by using one of these glues, the connection is final.

Watch the video & learn how to make this 3 way joint

Watch the video to see how I made the castle joint.
It was the first time that I have ventured into this connection.
I thought this woodworking joint would be difficult to make, but I must admit that this is a very simple connection and very easy to learn.

How to make a castle joint step by step

Step 1 | Preparation

To start building this 3-way wood joint, you saw the parts with which you want to make the castle joint to the correct length.

This woodworking joint will work best when you can use 3 parts of the same thickness.
Preferably, use square parts where the height of the workpiece is equal to the width.

However, to make a castle joint, different thicknesses in the wood are possible.
When using different thicknesses, you will have to recalculate the dimensions for the notches according to the wood used.

But wait!

Before you grab the wood you want to use, there is something you have to keep in mind when choosing the wood for making a castle joint.

Earlier in the blog, I already mentioned that you should use wood that is thick enough to ensure the strength of the connection.

When you will watch the pictures in the step-by-step guide below, you will see that, in many cases, only one-third of the wood will be retained when making these parts.
That means the wood will lose about 3 times its strength at that point.

To make sure the wood will be strong enough, make sure those points are at least 0.79 inches (ca. 2 cm) wide.
That means that the wood you will use to make this castle joint should be three times as wide.
Converted quickly, it means that you can get started with wood that has a minimum thickness of 2.36 inches (ca. 6 cm).

Later, by joining the parts of the castle joint, they will reinforce each other so that you are sure of a solid and strong connection.
Also, by sliding the parts into each other, you can secure the castle joint.
That way, all the pieces stay in place and can’t slip apart.
You can make this connection even stronger by adding wood glue between the connected parts.

Step 2 | building “the castle”

Ok, now that you have learned more about the wood that you need to make the castle joint, you can get started.
Below, I will explain step by step how to make the castle joint, starting from square wood with dimensions of 2.36 inches (ca. 6 cm) by 2.36 inches (ca. 6 cm).

Start by making the vertical part.
In this part, 2 slots need to be made, in which the horizontal parts will fit later.

To make these slots, divide the width of the wood into 3 equal pieces.
In this case, that will be 0.79 inches (ca. 2 cm).

Mark a parallel line at this distance, measured from the side of the wood.
Do this for each side until you get a pattern, as you can see in the picture below.

Now draw a transverse line indicating the end of the trench, measured from the end of the workpiece.
The distance from this cross line is the same as the width of the wood, in this case, 2.36 inches (ca. 6 cm).

Now you can start to make your first cuts.

It is best to use a fine-toothed handsaw for this.
I used a Japanese handsaw, which I recommend using to make connections.

When cutting the slots with your handsaw, do not cut on the marked lines. You better cut just next to the marking lines on the inside.
When all rough cuts have been made, you can start removing the excess wood up to the marking lines.
To touch up the edges up to the marked line, you better use the sharpest possible chisel for this. 
The sharper your chisel is, the faster and finer you can work.

When you are done, you should have a piece that looks like this picture.

Step 3 | making the horizontal parts

Ok, the first part has been made.
Now you can start making the horizontal parts.

This is actually twice an identical piece that you have to make.
Later, you can push these parts into each other at right angles.

Start by marking the lines where you need to make the cuts.
A notch must be made on both sides of the wood that is the same width as the vertical wood, in this case, 2.36 inches (ca. 6 cm).
The depth of the cuts here is also one-third of the width of the wood, so 0.79 inches (ca. 2 cm).

To make the notch, you will also have to work with the handsaw here. Make a cut on the 2 marked sidelines to a depth of one-third of the wood.

Remove the excess wood with a hammer and chisel and make the bottom of the slot as flat as possible.

To be able to slide the two horizontal parts together, an extra notch has to be made in the middle of the just made narrowing in the wood.

The width of this notch is the same width as the narrowing, or equal to one-third of the total thickness of the wood.
The depth of the notch should be halfway down the wood.

Mark the lines where that notch should be, as shown in the photo below.

After marking these lines, you can cut through the marked lines with the handsaw and remove the wood with a hammer and chisel.
After making the notch in both pieces, your two horizontal workpieces should look like this:

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Step 4 | Assembly

Now that you have made all the cuts, you can assemble this castle joint.

How these pieces will fit together will depend on how accurately you marked and made the openings.

So it is important to invest enough time in making the openings.
The more accurately these are made, the better and the more beautiful the connection between the different parts will be.

Now, to assemble the 3-way wood joint, take the vertical piece and slide 1 horizontal piece into one of the slots.
Pay attention to that the notch made in the narrowing points upwards. Check the picture below to see how this part should be mounted.

Now take the second horizontal part and slide it in at right angles to the first horizontal part.
Make sure that the notch now points down.
In this way, the two horizontal parts interlock.

You have now made a solid 3-way wood joint, or castle joint, that looks like the picture below.
To make the connection even stronger, you can apply wood glue to the joints.

As mentioned before, when you make this 3-way wood joint, make your marking lines as accurate as possible and use sharp chisels.
The more you practice on this woodworking joint, the better you will be.

So do not give up after the first time you make this castle joint.

Don’t Stop Now! Explore This Next:

Now that you have read this article, dive deeper into your woodworking journey with more handy tips and tricks. Discover three simple techniques to round over inside corners or learn creative ways to put your sawdust to good use. Click here to continue honing your skills and making the most of your woodworking projects!