Joinery is an important part of woodworking, which helps in conjoining pieces of wood. When it comes to the most basic form of joinery, the one thing that comes to mind is box joints. These are one form of finger joints that interlock together very simply. But even though a box joint is very basic, it still can be a tad bit difficult. Besides, to master the art of joinery you have to master all these basic joints first. So in this article, we will be giving you the ultimate guide to making box joints.
To make box joints, you simply need to cut pins and sockets that are 90-degrees from each side. You can do this by hand using a handsaw and chisel. A router can also be used to cut out the pins and sockets using a jig. You can make a jig for a table saw as well and it will cut the pins and sockets for the box joint relatively easily.
Box joints are a type of finger joint that are pretty fun and easy to make. Any finger joint is the kind of joint that can interlock with each other like how fingers would. So in this regard even dovetails are a type of finger joint, though more advanced. Box joints are easy to make with hand, router, and table saw compared to a dovetail. But precision is required to acquire 90-degrees on all sides and to cut the pins and sockets at equal lengths. Otherwise, they might be too tight to fit together or become too loose and not conjoin properly.
How to Make Box Joints by Hands (Step-by-Step guide)
To make a box joint by hand you will need a measuring square, marking gauge, dividers, paring or flathead chisel, hand saw or dovetail saw, fret saw, and a marking blade. With all of these items, you will be able to get perfect box joints by hand.
Step 1 – Measuring the Sockets and Pins
The first step for making any joint is to get the measurements right. So take your divider and mark out 4 to 6 partitions on the end grain side of the wood. The pins of the divider will dig in the end grain and give you a good idea of the measurements.
Now take your square and make sure that it is parallel to the wood, using your marking blade carve out a line where the divider dots were. Now you know where to place your dovetail or handsaw to start cutting. But to find out how deep we need to go, you will need your marking gauge.
Take your marking gauge and measure the thickness of the other plank that will interlock with the first one. Using the gauge, mark the first piece to find out how deep the saw will be cutting. Now you have perfect measurements of where to cut and how deep you need to go.
Step 2 – Cutting Corner socket Using Handsaw
Cutting the first socket in the corner is easy and does not require a lot of tools to do so. With the marks that you have already made, start cutting using the saw of your choice. If you are not sure of your hand saw cutting skills, try to leave a little space between the mark and the saw while you cut.
Step 3 – Paring and Filing of Excess
The slight margin gives you enough freedom to then take a paring chisel and slightly carve off the wood exactly where the marks are giving you perfect 90-degrees. If the excess between the marks and cut is pretty narrow and you don’t want to risk making it too loose with the chisel, just file it down using a wood file.
Step 4 – Cutting Other Sockets
With the corner, you can cut the socket out with just the handsaw, but now that you have to cut one out from the middle, you will need a fret saw for the job. Now a fret saw can cut and rotate in tight corners, though depending on the type of wood you are using, it might make it hard for you to use one properly. First using a dovetail or handsaw, cut from the end grain vertically to the mark from the marking gauge. Now slide in your fretsaw and while you are moving in the cutting motion turn it sideways to cut off the piece for the socket.
Step 5 – Paring and Cleaning Other Slots
Once the slots in the middle are cut, you need to clean these and make sure they are exactly 90-degrees. To do that use a square to keep checking if you are at the right measurement or not. Use your paring chisels to make sure you are right at the marks and afterward using a file just clean it up enough if there is any excess.
Step 6 – Replicating these Results in Another Board
Now use the board in which you have cut the sockets and pin to measure out where you need to cut the other board for replicating the results. But make sure to use the marking gauge, the square, and the divider again to make sure you are doing it right.
Once done with 4 boards on each corner, you can then join these together into a frame that is held together by each other. You can always use glue to ensure that the joint sticks, once that holds it will be strong.
Here is a detailed video on how you can make box joints using hand tools only:
If you check the video out you will see how after making box joints on one board, it became pretty easy to replicate the results on the mating/interlocking piece.
How to Make Box Joints With a Router (Step by Step Guide)
To make box joints using a router, you will either need a router table or design a jig to make a makeshift router table stand for your handheld router. Other than the router table you will also need to design a jig for cutting box joints.
Jig for Making Box Joints on a Table Router
So first of all, you need to measure up how big your table is, and if it has slider support, then all the better. If you are using a makeshift table router, then just measure it from one end to another. Take a board that is 2 inches bigger than the table itself on each side. The board can’t be too thick otherwise you will need a longer drill bit to cut box joints that are deep enough.
Now stick two-inch pieces of scrap wood as tall as the board for the jig on the two ends where you had left the space bigger than the table. These two pieces on the far ends will hold the jig straight and true when you are sliding it towards the router bit at the centre of the table. Now you need to make a board to hold the piece of wood that you will be cutting a box joint in. Make sure the holding board is big enough so that you are able to use clamps to hold other boards on it.
Now you need to install a pin in the jig which will help in cutting pins and sockets for box joints without needing measurements. This pin will also help in holding the piece without a clamp after the initial cuts. To make the pin, first, you need to cut the holding board with the router to find the proper size of the pin. Cut a small pin with a table saw or a handsaw and slide that into the kerf from the router into the holding board.
Now you need to make a stop in the jig that will block the router from cutting into the holding board itself. We want the jig to stop right where it cuts the piece of wood you want the joints in. You can do this by sticking a piece of scrap wood behind the jig as a stopper. Or you can stick the stoppers on the table itself where you want the jig to stop.
Note: When you stick pieces of scrap wood on your jig with glue, you should also drive in screws to make it a solid construction.
To learn how to make the jig, check out this easy video guide:
If the jig seems to be a bit too troublesome for you to make by yourself, then you can buy this Rockler Wood Router Table Box Joint instead and save yourself the hassle and time. But it is always good to make your own jig instead of buying one as you can customise it to your needs.
Step 1 – Setting Up
Once you have attached the jig that you have made or bought to the router table, you need to hook up a suitable bit to your router. The router bit needs to be as big as the size of the sockets you want on your box joint. If you want the socket and pins to be bigger and thicker then you need to have a bit of that size. With your own customised jig, you can decide how big boards you want to accommodate on it.
Step 2 – Making the Initial Cut
Once you have the jig set up on the router table, put the board you want flush against the pin and clamp it tightly with the holding board of the jig so it does not move. The jig pin is going to be the star of this whole jig as it will allow you to make sockets and pins of equal sizing without needing measurement. Once you make the first cut by sliding the jig towards the router, put the first socket of the box joint into the jig pin.
Step 3 – Repeating the Process Throughout
Once you are done with making the initial cut, just slide the first socket into the jig pin and repeat this process as you move forward in the same manner. Keep sliding the jig pin into the sockets of the board that you just cut with the router and make another cut on the side.
Step 4 – Making the Outer Cut on Interlocking Box-Joint Board
In the first board you made the cut in between, but to make the initial cut on a mating or interlocking piece, you will need to slightly change your approach. Take that first piece you carved box joints into, slide it into the pin at the end, take another board, and put it flush against that first piece. Now clamp the piece with the holding board and make the cut.
This will make the first cut on the outside, to make the next cut just push that first socket against the jig pin and clamp the piece again for stability. This is because the pin isn’t holding the board from both ends. Now make another cut and then everything will be repeated from the previous steps. Once you have done the process on both ends of all four boards, use glue to stick these together and you are done.
How to Make Box Joints Using a Tablesaw
Making box joints with a table saw is incredibly easy, but you do need to make a jig for it and a dado set of blades. To make the jig you just need to attach a board that acts as a fence to the mitre gauge of the table saw. Once you do that, cut a kerf and attach a pin to the jig, this pin will do the same job as the jig for the router table, to hold the socket of the box joint in the boards.
Once that is done, make a pass on the fence itself making sure there is half an inch of space between the jig pin and the blade itself. Now make a pass to create a kerf on the fence, once that is done, it is time to cut the box joint sockets and pins on the boards themselves. Start by making the cut by placing the board flush with the pin and passing it through the dado on the table saw.
Now slide the jig pin into the socket of the board and make another cut, and keep repeating the process. With a table saw though, you can make more than one board at a time, so take advantage of that. Now when all the boards are cut on all sides, use glue to attach them together.
Here is a video of how you can make the jig yourself and cut box joints on a board with a table saw with ease:
What is a Box Joint Best Used For
A box joint is best used for joining two pieces of wood together to create the shape of a box. While making a box is the best use for a box joint, there are other uses for it as well, for instance, you can create a wooden frame as well. Either way, the best use for a box joint is for making large boxes, drawers, chests, and small decoration boxes.
Although there are other joints that can also fulfil that purpose, you can even do the job without using joints and just dowels and screws. But the beauty of a box joint or any other finger joint is much more appealing than that of using dowel pins and screws.
What is the Simplest Way to Make a Box Joint?
Once you use all the methods we mentioned above to make box joints, you will realise that the best way to do it is by a table saw. First up, the jig is incredibly easy to make for the table saw with a mitre gauge and dado set. You don’t even need to make a stopper for the jig and you can even do more than one board at a time. This saves time and resources as you can do the job that might take hours within minutes.
The second easiest would be to cut a box joint with a router because once the jig is done, you can make joints one after another without pause. Making box joints with the hand is not that hard either, but it takes patience and accuracy on your end to get perfect results. Besides, you have to measure again and again to ensure you are not off by a margin.
How to Fix a Tight Box Joint?
If a box joint is too loose, then there is not an easy way to fix that. Rather than risking the integrity of the joint due to it being loose, making a new one is easier. But if a box joint is too tight, there are a few ways to fix it. You can either take a wood file and make a few passes to remove excess material off the joint. Once you do that check if the joint friction fits without having to hammer it.
Another way is to use a paring chisel and shave off very small quantities of excess wood. See if that allows the tight box joint to loosen up a bit. You can sand the piece using a small block as well, though that might take a bit more time depending on how tight the joint is. Either way, filing, sanding, or shaving off the excess from the tight joint will do the trick.
FAQ (Frequently Asked Questions)
What is the difference between a box joint and a finger joint?
A box joint is a type of finger joint and one of the most basic ones at that. A finger joint basically describes a joint in which a socket and pin conjoin two pieces of wood together like how fingers of two hands interlock between each other.
Does the box joint hold the pieces together without any support?
A box joint is the best type of joint for conjoining two pieces together with the help of glue. This is because it provides the glue with more surface area to stick together. So to answer the question, no, a box joint does not hold pieces together without support, you need glue for it to stick and endure.
Can I use the jig for the router table with the tablesaw to make box joints?
Yes, you can use the same jig for both a router and table saw. But if you have a mitre gauge on your table saw then you don’t need to make a sliding jig. As the mitre gauge will help with sliding the jig back and forth. With a little variation and customization, you can create a jig that works for both the table saw and a router table as well.
Is making the box joint by hand easier than using a table saw or a table router?
No, making the box joint by hand is probably the most difficult method out of all. A table saw and table router can make box joints in minutes while cutting out one socket and pin by hand can take a lot more time.
Final Thoughts
Being able to make a box joint is the first step in being able to make more difficult finger joints. It is one of the most basic joints to learn if you want to get into joinery. With the help of jigs, you can make perfect box joints every time without hassle. Once you get a hold of this one, you can make other joints like dovetails just as easily by designing jigs specifically used for them. Hope our ultimate guide to making box joints was of help to you and now you can make them whether you want to make it by hand tools, a table saw, or a table router.
