Single Blade Box Joint Jig Plans

I was really happy with the way the first version of this jig turned out, so when it was time to rebuild it in a more accurate and efficient way, I decided to film the process too. The results were great, pretty much perfect fitting box joints straight off of the tablesaw. I think this may be a really helpful jig for a lot of woodworkers like myself who have no dado set, but still want to create strong joints on the tablesaw very quickly.

Single Blade Box Joint Jig
Single Blade Box Joint Jig

How does it work? It works by having your work pieces clamp to a sliding fence which follows a cutting template. You make your cut, slide the fence over and make another cut. A ‘key’ limits the range of movement based on the cutting template you have setup. You are able to create multiple joint designs and cut them all out as easily as the standard one shown below.

Straight off the jig, glued and sanded. Good enough for me.
Straight off the jig, glued and sanded. Good enough for me.

The jig was made from scrap MDF, a short 2×4 offcut, and a small length of 19mm (3/4in) pine for the building blocks. It took just over an hour to make and cost me nothing, I had enough scraps on hand. It’s saved me a huge amount of time and money already; I’ve put together 6 drawers with it now, faster than ever before, and I didn’t have to use a single screw or purchase a dado stack to do so.

Single Blade Box Joint Jig
Click here to download free PDF plans

Click here to download the SketchUp file for this jig (compressed in a zip file)

 

Building the actual jig is fairly straight forward. I put it together using pocket holes to save time, but you can build it anyway you like. (My MDF did split in a couple of points but nowhere critical.) The plans have measurements in them but they are just a guide, they don’t need to be followed perfectly. Just build it to the size you require and to the stock you have on hand. I’ve used this version to make drawers that are around 1 meter in length. I cut all four sides at the one time, no issues at all.

The first step is simply making a sled with a 90 degree fence that slides on your tables mitre tracks. I used the 2×4 to provide strength, a platform for the joint building blocks and as a blade guard.

My perfect fitting key
My perfect fitting key

The most crucial part of the setup is the object you use as your ‘key’. The key is the part that registers against the joint blocks, limiting your movement. The key must be exactly the same size as the kerf that is left by your saw blade. Because the blade travels back and forth with the jig, if your key is off by 1mm, your joints will be 2mm off. If you are off by 2mm, your joints will be off by 4mm. It is super important that you find a key that is the same width as your kerf.

It took me 5 or 6 attempts to find the perfect key to use. I started with a screwdriver, then various screws and even an Allen key at one point. Eventually I used a bolt with the perfect diameter, which I drove right through the fence so that it wouldn’t wobble or waver. Don’t fret if your joints aren’t perfect at the start, just grab your callipers and look through your junk screw and bolt buckets for a better key.

Joint Building Blocks
Joint building blocks sandwiched in together. (Yes the MDF did split, however it doesn’t affect the use or accuracy)

The joint building blocks are the parts that create your cutting template. They are setup in what looks effectively like a castle turret style, one tall, one short, one tall, one short, etc. The leftmost piece is cut to fit in tightly and lock the rest in place. Literally use it to jam the rest in. This way the pieces are nice and tight for cutting, but can still be removed easily when you wish to change the joint design.

The key can move freely above a short block, but stops when it reaches the edge of a tall one. Once you have cut all of that block out, you lift the slider and key, travel to the next short block and continue cutting. This means that the width of your finger, will be whatever the width of your tall blocks are. The longer a key, the more chance it will wobble, use something short and stiff.

Create different sized joints easily
Create different sized and configured joints easily. Make the mating joint for this one by simply reversing the order!

If you decide to make a different pattern than the traditional box joint, you can. You could cut joint building blocks from different thicknesses of wood for example. You could have a 19mm finger, then 9ml, then 19mm again for example. All of these can be cut using just the one blade and require no other setup once you have them jammed in place on the jig.

As for cutting, it’s pretty simple. You position two of your box sides to the sliding fence. Then offset the other two by the width of your first joint. This is easily done by cutting a building block to use as a spacer. Insert it the spacer, clamp it all up and then remove the spacer. Then make your cuts.

In writing, it seems like a lengthy process. If you watch my video you’ll see it actually takes no time at all. The jig is essentially always setup. Cutting 4 lengths of a drawer at once takes maybe a minute to clamp, 2 minutes to cut. Repeat that for the other 4 ends, and you are done in around 5 minutes.

What do you think? Be sure to leave me a comment here or on youtube with your thoughts. If you’ve made one or have improved the design, please let me know.

Disclaimer: I know it’s not better than a dado or stacked blade set. But I don’t have one of them. Feel free to send me a couple of hundred dollars and I will purchase a dado set and throw this jig away!

Please follow and like, it helps me!

  1. Great idea, if you ever decide to make a next version may I suggest in place of the blocks you use 1/4″ fingers mounted on a dowel that you can rotate up as you want to create the box cut you desire, add a bolt or machine screw through the one end to add clamping pressure so the fingers don’t move as you cut your pieces.
    Definitely make your jig for my boxes.

    • Hi Bob, yep I’ll do things better on the next version, had heaps of good tips from people who have seen it. Send through some pics when you build something with it! Cheers, Mario

  2. Thanks a lot for the idea Sir, it’s right what I’ve been looking for. Table saws for Europe don’t let you use dado blades, so making finger joints without a router is a real pain. Thanks again, I’m going to build it.

  3. THis was just what I was looking for. Good head, Mario

    Try a twist drill shank for the guide pin. the are available in all sizes.

    Liked A Bakers dodge, too- going to try that!!

    Cheers, Thomas

    • Hey Mario! Thanks for posting plans. I made two this weekend ( the first was slapped together quickly, the second had a couple changes. I added a toggle clamp to the front fence. You can see what I did here.
      https://youtu.be/1ngzgHw4bhY
      Cheers

      • That’s fantastic Clemens, thanks heaps for the video! The toggle clamp looks handy if a little bulky. But so long as it works, that’s the main thing. Jigs don’t need to be pretty! Cheers, Mario

    • Some more information would be good, what sort of error are you getting? I can download, extract and open the file with no problems. Perhaps make sure you have the latest version of SketchUp, that would be the first place to start looking.

  4. Hi Mario,
    What an absurdly simple concept!. I made one and it works fine but finding a ‘pin’ was a pain. I started by filing a nail into an oval shape and rotating it until the joint was almost perfect but I found that the nail would flex under sideways pressure and and the joint fit was affected. Then, I found an old small set of Allen Keys (hex wrenches). Find one where the flat side is smaller than the kerf and the corner is wider than the kerf. Grip the Allen Key with pliers and force it into a vertically drilled hole in the sliding part. Adjust the joint fit by rotating the Allen Key slightly (and I mean slightly). The key is stiff enough to resist flexing (good steel) and the jig can be adjusted when you change blades.

    • Yep the key is the critical part of the build, that’s for sure. Good tip with forcing the allen key, it follows my thinking; when in doubt, brute force to the rescue!

  5. Hi, Thank you for posting this video and for the design! I will definitely be building one of these for myself. Great Idea

    • Not a problem Nick, heaps of other woodworkers have made their own and it seems like it’s working for everyone else as well as it does for me! Best of luck!

  6. Thanks for the plans, something simple enough that I can build it that will work with a UK table saw. I look forward to playing with it.

    Trev

  7. I modified the design slightly. Instead of using a screw for the spacing guide, I mounted a inside caliper (inexpensive Harbor Freight). When I cut joints I mount 1 to 4 portable circular saw blades on the arbor (saw blade width less than joint so each joint cuts in two passes) To set the caliper I cut part way into a scrap and then use the inside caliper to set the pin width.
    I also glued a stack of template pieces together and then sawed two sides so the stack is flat. When I need to make the mating piece I just have to rotate the stack 90 degrees. I have made a special stack for box building with one of the center blocks a blade width wider than the rest. When I assemble the box I can cut the wide joint and it looks like I made the lid and box as two pieces rather than one and sawing in two.
    I modified the sketch up plans for the caliper, but do not know how to upload to this reply

  8. must build this idea
    here in europe stacked dado blades aren’t available;in fact they’re actually illegal!
    (something to do with the slow-down time of the blades)
    having to eyeball pencil lines to a blade and VERY carefully cut the right (or left!) sides of the lines, on a home-made crosscut sled, i did cut accurate 1/4″box joints in plywood; but it was real P-in-the-A, and not something i would like to do often.

  9. Very nice, Its great that there are still people who take time for others, thanks and keep up the good work. craig

  10. I forgot to add that with the screw threads filed off on left and right sides, I can make a very minor adjustment to the screw width simply by turning the screw a touch. ( the screw is oblong with sides of threads filed off and front and back side threads still there). It’s another cool adjustment that’s simple but a lot like the more sophisticated dado type jigs with t-bolt adjustment features. I like your idea better as I don’t need to spend dado money either, rather buy some cool wood. I also built separate slider units for each template block size, 1/4, 3/8 and 1/2. In addition, I put two screws in (one always extracted) so I could go with first finger full or half full. That added a neat look to the finger arrangements. Thanks again for getting me started.

  11. I made one, and I added an adjustable block with screw press to squeeze the template blocks in place. Also I used a screw, and it was just a tad wide, so I filed off the screw threads and the fit came out perfect. Easier to file off threads than to find another narrower screw. Also without the threads, I’m not worried about the pressure of the threads cutting into the template blocks over time which would effectively have narrowed the screw width. Great tool and appreciate your help.

  12. Mario,

    Great idea, simple and effective. Love it! Have you tried your technique with smaller size fingers…like 1/4″ ?

    Rick

  13. Hi Mario, love the design. I just looked at the plans and it appears to go from step 5 to step 7. No step 6. Am I missing something or is it just a typo? Thanks again for the great design. -Fred

  14. Mario,
    Great idea, thanks. I am now starting woodworking as a hobby, retiring after 40 years of being a paramedic.

    I plan on building one with the following modification. I will sandwich a hardboard extending 3 in beyond the face of the fence between the runners and base plate. That way the boards would not ride on the table fence but be supported. Similar to Gary’s adaptation on a sled.

    I also like the idea of a screw system to lock the blocks in place.

    • It’s a great hobby to get into Joe, it only has to be expensive if you want all the trimmings at once. And yep, I think a built in ledge for the work piece to ride on is the way to go. Cheers, be sure ot send through a photo when you’re done, love to see it.

  15. Hi Mario, thanks for the plans, found you via Jay Bates, top Man! I’ll certainly be making this soon, having watched your update.

  16. Hi Mario,
    I made one today and tested a few cuts and it worked great. Thanks for the plans. I used a wedge to hold all the blocks in place.
    Larry

    • Cheers Larry, glad it worked for you. If I rebuild it one day I probably will make some sort of screw / block system to tighten it up, but for now the wedged in block works a treat!

  17. Thanks for sharing the plans Mario. All of the other plans I have looked at are so much more complicated to build. I hope to build yours this week.

  18. Hi Mario, greetings from Zagreb, Croatia 🙂
    I’ve been looking for months to find appropriate and affordable jig but till today with no success, almost every one of those required dado blades and like you I didn’t want to spend almost 200$. Finally your excellent design, so simple yet so efficient, inspired me to start making one of my own, as soon as this annoying flu leaves my body.
    Once again many thanks for sharing this ingenious plan and videos. As soon as I finish my jig will send some pictures to you, but please keep in mind that my woodworking experience is just a couple of months old 😉
    Looking forward for more ideas and projects from you,
    Best regards, Dario

    • Looking forward to seeing your version of the jig Dario, I hope you’ve shaken the flu and are back to being in the shop. Glad I could save you some money too! Good to hear from you and I appreciate you checking the site out, all the best, Mario

  19. Aussie ingenuity at it’s best. Thanks mate for the plans I will be customising to fit on my existing crosscut sled… Then I wont need a spacer between the workpiece and the table….

    I love that you can just use simple blocks as spacers so any size/wood will work. I will be using lego blocks which allow a very customisable profile and hold themselves in place…

    • Lego blocks? I think I’m going to need a photo of that! Would you glue them together? If they were freestanding they might wobble slightly I think? If so, your cut will be off. Regardless, let me know how it pans out!

  20. G’day, I have been looking for something like this for ages and have even been tinkering with a few ideas. The simplicity of this design is breathtaking and yes I have had yet another “why didn’t I think of that?” moment.

    It seems to me that this design should actually be able to be incorporated into (or rather onto) my existing sled to simply it even more.

    BTW I am not sure you are aware of it or not but the text “Click to download the SketchUp file for this jig” is NOT a hyperlink and therefore there is no link to download the SketchUp plans.

    Cheers, and well done!

    • Hi Gary, thanks for commenting. I guess with a bit of thinking you could easily modify this to fit it onto your existing sled to make it even easier to build. Be sure to send me a photo if you do. I’ll get that sketchup link fixed up as soon as possible too. Cheers, Mario

  21. Cool design. It can cut smooth bottomed cuts where my screw advance jig can’t very well.

    You don’t need two sizes of block for the pattern. You just need one size that can be tipped long way up or long way out. That would make it easier to build fancier patterns because the mating piece is done just by reversing the tipped-up and tipped-out pieces.

    I’d also put a knob through a threaded hole with a sacrificial block on the end to hold the pattern pieces tight.

    • The tightening knob is a good idea, that would be better at squeezing them together after you adjust the template thicknesses. And yep, you’re right, one length of the finger blocks would work just as well as two, I won’t bother with the shorter ones when I make some at different thicknesses. Thanks for checking it out!

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