How To Make Biscuit Joints With A Router

Updated 3/10/2023

Knowing how to make biscuit joints with a router can be an easy task for any DIY’er. If you’re new to the whole woodworking thing, no need to worry.

In this guide, you’ll learn how to create a biscuit joint that will be useful for some projects!

Even though it’s one of the less common joints that are made in fusing two pieces of wood together, it has the unique attribute of being one of the strongest in terms of strength and durability.

Creating these biscuit joints can be done with a power tool known as a biscuit joiner.

But what if you don’t have a biscuit joiner? Or worse, what if you can’t afford one? Not to worry, you can get the job done with a simple router.

Before giving you the step by step instructions on how to make biscuit joints with a router, we’ll explain what a biscuit joint is and what they are used for.

From there, you’ll learn how to create these joints.

Keep in mind that if you plan on making fewer biscuit joints than some DIY users, a router will be a more acceptable option.

If biscuit joints will be a recurring role in your DIY projects, that’s when you need to invest in a biscuit joiner.

Doing these frequently with a router may lead to wear and tear in the long-term.

With that said, let’s get right to it by first explaining what a biscuit joint is!

What is a Biscuit Joint?

A biscuit joint is used when you intend to put two pieces of wood together. If you think putting them together using good old fashioned wood glue or screws might be the solution, you might run into a few problems.

Of course, that can lead to poor joint integrity and both pieces of wood won’t stay together.

To mitigate this problem, you’ll need to create a biscuit joint. Since you don’t have a biscuit joiner, there’s only one tool that you can use to put these pieces of wood together and help keep them together.

That is none other than a router.

With your router, you can cut small pieces of wood that, when put together, form shapes that look like biscuits.

That’s when a joint is formed between these two pieces of wood (hence the name).

Before you join the two pieces of wood together, you can still use glue to add a bit more to the joint’s integrity.

Once the glue dries, the recesses will swell and thus strengthen the joint further.

Biscuits are fairly strong and thus will do an excellent job in making sure that the two pieces of wood

Biscuit joints will be much stronger than such joints as butt joints. It will allow you to align and combine two pieces of wood perfectly.

Keep in mind though, a biscuit joint may not be suitable if you’re planning on putting together two pieces of wood with the intent of adding additional weight to it.

The joint may weaken depending on how much you put on it.

What is the Proper Spacing for Biscuit Joints?

Now, we’ll discuss what is good enough spacing for biscuit joints. Because of personal preference, the spacing may differ. However, most biscuits should be placed every six to twelve inches.

To measure the spacing between two spaces, you’ll need to measure the center of one biscuit to another.

Remember that if you have too many biscuits, you risk weakening the joint. And the integrity will not be as good as you would expect.

Also, cutting the biscuit too close to the edge may cause splitting. Biscuits spaced too far apart will allow weak points to form within the joint.

So it would be ideal to keep the biscuits spaced between 6 to 12 inches (or get away with them being 8 to 9 inches apart).

Make sure that your edges are three inches away from the edge. The reason why this is important is that you want to prevent as little spillage as possible.

Plus, you want to prevent any weak spots or splitting.

Types of Biscuits (and which ones should you use)

There are three types of biscuits, each with their own corresponding sizes. You have #20, #10, and #0 biscuits. Let’s take a look at the purpose of each one:

#0: These biscuits are the smallest of the bunch. Therefore, they can only be used for smaller projects. #0 biscuits (measured in mm) are 47 in length, 15 in width, and 4 deep. Simply put, these will be used when working with narrow sized timber.

#10: If you are looking for what is considered the standard-size biscuit, the #10 is what you need.

These are perfect for pretty much any common project that calls for biscuit joints. These are slightly longer than #0 (53mm) and are measured at 19mm in width.

Please note that from here on out, the depth of these biscuits will always be 4mm. With that said, let’s discuss the last biscuit.

#20: Obviously, these are the largest-sized biscuits. This means these will be used for your larger projects.

You’ll notice that the larger the biscuit, the more force can be sustained.

As mentioned, the depth of these biscuits is measured at 4mm. This means you’ll need to cut biscuit grooves of that size to ensure a perfect fit.

When using a bit to cut your grooves, you’ll need to find one that is closest to 4mm.

How to Make Biscuit Joints with a Router

Now we get to the meat and potatoes of this guide. You’ll now learn step by step how to make a biscuit joint with a router. This is the best possible option in the event if you don’t have a biscuit joiner.

Thankfully, this is the most cost-effective option. A router will be sufficient if you cannot afford a biscuit joiner.

If you don’t have one, you can find a good quality router for under $200.

A couple of things to remember when using a router to perform this specific project…

1) It will feel weird and awkward at first.

2) Compared to using a biscuit joiner, the job itself takes longer with a router.

Regardless of what you use, you’ll still get the job done. You will achieve the best results as long as you follow the steps below.

1) Alignment and marking the locations

First and foremost, you’ll need to decide which edges will be joining and the direction they should be going in.

Once you’ve made that decision, you must align them properly. Next, you’ll need to determine where the biscuit joints will sit.

Next, use your tape measure and start from the edge. You’ll need to mark a line three inches away from each edge.

This is recommended since you’ll want to prevent as much spilling and splitting as possible.

Now, you’ll need to measure the length between the three-inch markings you just made. Then, you will divide it by the number of biscuits you’ll be using.

At this point, you’ll already be using two on each edge.

So now, you will divide the distance between the edges by three so you have equal spacing for the rest of the biscuits.

Assuming you are using four biscuits, now you’ll need to calculate the spacing for the other two that will rest in between.

After the calculation is complete, mark where these biscuits will be placed.

Going forward, if you are putting together biscuit joints, you will have two biscuits in place on each edge.

Once you measure the distance between the edges (regardless of the measurement), divide that by three so you have a good idea of how many biscuits you’ll need to use to form the joint itself.

Once you have your measurements and markings done, that’s when you’ll need to take that second piece of wood and place it against the first piece.

The purpose here is to transfer the markings made from the first piece to the second. Alternatively, you can make the same marking once more with your measuring tape and pencil.

2) Setting up the router

Now that you completed your alignments, it’s time to set up the router to perform the task. That’s when you need to install the router bit so you can be able to cut the grooves.

Make sure that the bit that you use is at the correct depth (in this case, you’ll need a 5/32 inch bit since it’s the closest to 4mm).

If you are using a cordless router, make sure that the battery is charged, so you are able to get the job done without any interruption.

Also, be sure to unplug the tool (if corded) so that you can prevent the router from powering on and cutting you in the process.

You’ll also need to install the bit outside of the guide that’s included on the router. Set the correct depth in the collet or check so the bit can stay in place when cutting the groove.

Ensure the collet is secure once you have the bit completely in place.

Now, you’ll need to set the depth. The foot of the router should be resting on the face of the wood.

The bit should also be cut in the correct location (close to the center as possible, not the edge).

3) Clamping and cutting the first piece of wood

Make sure that the first piece of wood is properly clamped. Once secured, take the foot of the router and position it directly near the first cut line. Switch on the router and gently push through the line.

You want to keep the foot of the router perfectly flat as you perform this task. You want to cut it straight and not at any angles.

As soon as the depth is reached, move the router an inch or more on either side of your cutting line.

Make sure that the cutting hole you make is two inches in depth. That will be deep enough, so the biscuits are held in place. Once you have made the hole, test fit the biscuit.

If the test is successful, repeat the process until you have completed the first piece of wood.

4) Clamp the second piece of wood

Now, remove the first piece of wood from the clamp. Once fully removed, you will now need to clamp the second piece. Just like the first piece of wood, you repeat the same process.

Make sure the biscuit holes are two inches deep and test fit them before moving on.

At this point, it’s pretty much rinse and repeat.

5) Dry fitting the joints

Before applying any glue, you should consider dry fitting the biscuit joints. This basically gives you a dry run test to determine whether or not everything can fit together even without a single application of glue.

Place the biscuits in each hole within the second piece of wood. Then take the first piece of wood and attach them both together.

If both pieces of wood are easily fused together, you have done it correctly.

But it never hurts to double-check. Once everything is nice and snug, you can then apply the glue.

6) Application of glue

Next, you’ll need to take the glue you’ll be using and apply it to the joints. Be sure that the pieces of wood are properly secure before performing this task.

For better grip, use pieces of scrap wood to ensure better security (and to prevent the clamps from leaving “bite marks” on the finished product).

Apply glue to each of the holes where the biscuits will attach. Once applied, you’ll need to carefully but quickly fuse the biscuits in their respective joints.

Even though the wood glue can be warm, it can dry fairly quickly after application.

Once the glue is applied, fuse the pieces of wood together, so the biscuit and the joint holes are attached.

You can tap the wood with the heel of your hand to give it enough force to fit through. Once everything is in place, you can check for gaps or any weak points.

If everything appears in good enough shape, you can remove the now fused pieces of wood from the clamp carefully. At this point, you should be finished.

Wrapping it Up

Creating a biscuit joint with a router is easy once you get the hang of it. It’s one of the best skills that you can perform with one powerful tool if you don’t own a regular biscuit joiner.

Make sure that with every biscuit joint you create, you can be able to secure them properly so they can stay together for an extended period of time!

Good luck, DIY’ers!