How to Make a Half-Lap Joint Jig for Faster Workflow | Free Plans

If you want to make a half-lap joint, you can easily do it on a table saw and a crosscut slide.
The only drawback is that it is very time-consuming.

So, if you need more than one half-lap joint, you need to find a way to make them much faster.
That’s why I recommend you making this half-lap joint jig for your workshop.

But how do you make a half lap joint jig?

Basically, to make a half lap joint jig, you make a right angle by joining two pieces of wood together.
By adding a system, you can mount this right angle vertically on your crosscut slide.
Now, when you clamp your wood vertically against the jig, and slide the crosscut slide over the saw blade, you can make half-lap joints.

Be sure to read this in-depth step-by-step guide carefully to learn how to build this half-lap joint jig.
Also, in this blog, you will learn how to make homemade knobs to secure the jig in place on your crosscut slide.
In the last part of this article, I will show you how to work with this amazing jig to create a lot of half-lap joints in no time.

If you have the same crosscut sled as mine, the half lap joint jig, you will learn to make in this article, will fit perfectly.

Remember that you can download the free half lap joint jig plans with dimensions to make this jig for your workshop.

This blog post is all about making a half lap joint jig and how to make half lap joints.
If you want to discover other, more specific woodworking joints, please check out this website’s woodworking joints category after reading this blog.

Disclosure: At zero cost to you, I may get commissions for purchases made through links in this post. I earn from qualifying purchases as an Amazon associate. Products featured are selected based on quality, performance, and reputation, regardless of affiliate relationships.

What is a half-lap joint?

Half lap joints are simple joints that are easy and quick to make and are used to join two pieces of wood.

In most cases, a half-lap joints will consist out of two pieces of wood with the same thickness.
With each of these two pieces, half of the material will be removed, so that the two pieces of wood fit together perfectly, creating a seamless connection.

What are the different types of half-lap joints?

There are different types of half-lap joints.
The most common is the right angle half-lap joint, but also the miter half-lap joint, the dovetail cross lap joint, and the regular cross lap joint are popular joints.

What is a half-lap joint used for?

Half lap joints can be used for a variety of purposes.
Most commonly, people use half-lap joints when building with frame timbers, such as in furniture carcasses, especially for making 90-degree intersections.

The advantage of this connection is that it does not add any extra height to the joint.

Are half-lap joints strong?​

A half lap joint is a strong connection because you remove no more than half the thickness of the wood from both pieces of wood.
When you add wood glue to this connection, this connection only gets stronger.
So to answer this question: YES, half lap joints are quite strong!

So if you are looking for a strong joint that is also visually appealing, the half-lap joint is definitely worth considering, depending on where you want to use this joint in your project.

If you need an even stronger joint, I can recommend you making a dovetail joint.

Watch the video & see how to make a half-lap joint jig

Here you can watch the video and see how to make the half lap joint jig.
After watching the video, you can continue reading the step-by-step guide to making this half-lap joint jig yourself. 

How to make a half-lap joint jig?

Step 1 | Preparation

As with any project, I started by cutting the parts I needed.

If you also want to make this jig, don’t forget to download the free plans, they contain all the dimensions you need to make the half-lap joint jig.

To cut all pieces to size, I used my crosscut sled, and my miter sled on my table saw.

If you want to know how to build these sleds for your table saw, click on the links to continue to the blog posts about these table saw sleds.
On those articles, you can download the free plans, and build them for your workshop.

Step 2 | Making a slot

On this jig, there are two toggle clamps attached.
These toggle clamps will hold the workpiece in place when you want to make half lap joints with this jig.
To make it possible to adjust the toggle clamps to the thickness of the wood you use to make a half-lap joint, slots must be made in the vertical part of the jig.

In order to make these slots in this part, I used an 8 mm straight router bit on my palm router.
To be able to make straight slots, I clamped my speed square on the piece of wood as a guide for my palm router.

To avoid burn marks, I made these slots in several passes, lowering the router bit on each pass.

Step 3 | Assembling the half-lap joint jig

After making the slots, I was able to start assembling the base of the jig. To connect all the pieces together, I used wood glue and brad nails.

The advantage of using brad nails is that they hold the pieces in place, and you can continue working while the wood glue dries.

The part of the half-lap joint jig, where you clamp your workpiece, needs to be perpendicular to the fence of the crosscut sled.
To keep it perfectly 90 degrees and to get perfect cuts, I made some triangular-shaped pieces to reinforce this jig.

The top part that keeps the jig perpendicular to the crosscut sled has two holes, and is longer than the bottom part.

This is to secure the half-lap joint jig to the crosscut sled.
You can see the differences between these two parts on the free half lap joint jig plans.

To make the holes in the perfect place, I took this piece, and placed it on top of the fence of my crosscut sled.
Like that, I could mark the distance equals to where the T-track is at the top of the fence of the crosscut sled.

On those marks, I drilled two 10 mm (0.394 Inch) holes through which the bolts can be inserted.
These bolts will ensure, together with the homemade knobs, that the jig can be clamped in place and cannot slip while making half-lap joints.

Once I had assembled the base of the jig, I took a narrower piece of wood, and attached two toggle clamps on it with screws.

Tip: Before screwing, it is recommended to pre-drill pilot holes to prevent cracks in the wood.

With these toggle clamps, it will be possible to quickly change the wood while making the half-lap joints.
These clamps ensure the speed with which you can work, so look out for high-quality toggle clamps.
The smoother they work, the faster you can make half lap joints.

Remember those slots I had previously made in the vertical part of the jig?
Because of these slots, now I was able to insert wood bolts and secure the piece of wood with the toggle clamps to the jig.
To distribute the pressure on the wood, and to prevent the wood bolt from pulling into the wood, I added a washer on the back.

When installing these bolts, do not overtighten them so that you can easily move the part with the toggle clamps up and down.
Due to the tension that you apply with the clamps when tightening the wood, this part will get stuck and no longer shift.

Step 4 | Making the homemade knobs

To secure the jig to the crosscut sled, I used homemade knobs.

I was able to make these star knobs with the drill press jig I made earlier.
You can make this jig yourself for your drill press thanks to the free template that you can download on this blog.

To sand and smooth the knobs, I held them against my homemade drum sander.
If you don’t have a drill press, you should check out my article, where you can discover how to make a portable drum sander from your cordless drill.

The knob has been fitted with a T-nut with a diameter of 8 mm (0.315 Inch), so that the knob can be screwed onto the bolts.
The T-nut has pressed into the knob thanks to my vice.
When you do this, do it carefully.
When the T-nut is pressed too quickly in the wood, there is a possibility that the wood will crack.

Now that the homemade knobs were ready, the jig could be mounted on the crosscut sled.
All I had to do was to slide two bolts into the T-track on top of the fence of my crosscut sled and place the jig over those bolts.

After adding a washer, I could place the homemade knobs like you can see on the picture below.

In the next part of this article, I’ll show you step by step how to use this half-lap joint jig.
So be sure to read on!

How to use a half-lap joint jig?

Briefly described, the steps tho use a half lap joint jig are:

• Adjust the saw blade according to the wood with which you want to make half-lap joints.
• Now set the jig with the correct distance from the saw blade.
• Clamp the wood vertically and make the first cut.
• Readjust the blade and jig according to the width of the wood.
• Make the second, horizontal cut.

Below, I will describe these steps more in depth.

The first thing to do to make half-lap joints with your new jig is to adjust the height of the saw blade.

Take a piece of wood with which you want to make the half-lap joint and place it along the saw blade.
Now raise the saw blade until it is flush with the top of the wood.

Then measure the thickness of the wood and divide it by two.

Half the thickness of the wood is the distance the jig should be placed from the saw blade.
Once the correct distance has been set, clamp the jig in this place by firmly tightening the homemade knobs.

The jig is now in the right position to make a correct cut, and you can clamp the wood against the jig with the toggle clamps.

Now make all the cuts that you need for your project on the end grain of the wood without moving the jig.

Once all cuts have been made, you can proceed to the next step.

Loosen the jig and move it just until the distance between the saw blade and the jig is the same as the width of the wood.

Once you have been able to set the correct distance, reattach the jig by tightening the knobs.

Next, lower the saw blade to half the thickness of the wood.
To check this, you can take a piece of wood from the previous step and place it next to the saw blade, as shown in the picture below.

Now you can make the final cuts in the process of making half-lap joints.

When you have worked very accurately, the two pieces of wood will fit together perfectly and your half-lap joint will be a success.

If it doesn’t work the first time, keep practicing.
The more you do this, the better the result will be.

To speed up your workflow, there is the option to use dado blades. But not all countries allow you to use them, and not all table saw will not be designed to install dado blades.

Take a look at another article of mine, — can I use dado blades on my table saw — to get all the answers about dado blades.