Super Simple, Single Blade Box (Finger) Joint Jig





Introduction: Super Simple, Single Blade Box (Finger) Joint Jig

About: Father, Woodworker, Youtuber.

I really wanted to create box joints on my table saw but I don't have the cash right now for a a Dado stack. (They are hard to come by in Australia) so I decided to make an accurate Single Blade Jig for my Table Saw.

The results are great, 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.

As a bonus, it costs nothing to make but an hour of your time, my own one was all from scraps.

I've a couple of videos showing how to make it on my YouTube channel; and you can download the PDF instructions from my website,

If you've any questions or comments fire away, there is more info about it on my site too.

If you like it I'd love to have you subscribe to my channel on youtube as well, more videos coming soon!

(and if it isn't too rude to ask, if you like this jig it would be great if you could send a vote my way for the tool competition!)

Enjoy, Mario!

Step 1: Single Blade Jig

How does it work? 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.

Mine 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 a dozen drawers with it and a few boxes, faster than ever before, and I didn’t have to use a single screw or purchase a dado stack to do so!

Step 2: Advanced Techniques! Variable Width Fingers!

All from the same jig with no difference in setup time!

You can mix and match your finger widths to create different effects, these would look wonderful in nice contrasting hardwoods. Not so pretty in 6mm MDF or cheap Plywood but it was literally all I had on hand I'm sorry!



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That's just fantastic. I also don't have a dado blade set and will build your jig.

Thanks for sharing !!!

That is awesome

Eine großartige Lösung nach der ich immer schon gesucht habe.

Vielen Dank Mario für diesen Workshop.

Grüße aus Wien,


Simply and great idea!

Interesting concept. I will definitely have to experiment with the design myself, since storage of one jig definitely beats keeping multiple jigs around in the shop.

I do have a couple of tips to improve your cuts. First is your spacers. Any solid wood spacer is going to change dimensions over time because of changes in air moisture - shrinking in winter and swelling in summer. That change is not going to be consistent since tangential and radial grain expand at different rates, which can cause a painstakingly accurately square block to turn diamond shape.

Construction grade plywood is notoriously not consistent thickness and not even close to being flat. Even two pieces cut next to each other may not be the same thickness. That inconsistency can build up to noticeable differences in measurement. Even cabinet-grade plywood is not as accurate as it use to be.

For spacers, I'd recommend (in order of my preference for stability) plexiglass or similar sheet plastic, MDO (an exterior grade MDF), apple-ply plywood, MDF, or Baltic birch plywood. Apple-ply plywood is a high-end plywood that looks similar to Baltic birch, but is heavier, denser, and more stable. And, accordingly, the price does reflect that. Sheet plastic cut offs can be acquired by developing a relationship with a local commercial sign maker. They toss many pieces of stock that is too small to safely hold in their CNC routers or are just not worth storing until the next time some client wants that color in that thickness. You should be able to get pieces for little to no money.

As far as the construction of the jig, I recommend apply-ply or Baltic birch plywood. Both will wear better over time than the MDF that you used. That said, you can't beat MDF's price when prototyping jigs. Also solid wood parts are prone to warping and distorting, as I mentioned with the spacers.

To reduce tear-out, apply a replaceable face to the jig. It could be 1/4" tempered hardboard, MDF, or plywood, but it should be repositioned or replaced every time you lower the height of the blade so that the stock that you are cutting is backed up with a zero-clearance around all edges of the blade. When cutting plywood or solid wood, you can also score a line with a utility knife at the height of the cut. This will let the fibers shear off rather than tear. That score line is considered traditional, and can be seen on many antiques, since 18th and 19th-century woodworkers laid out lines with marking knives, not pencils. There isn't a lot you can do about that tear out on the sides of those diagonal grained plywood, other than using a freshly sharpened blade intended for veneers, firmly holding the stock against the jig face, and slow your feed rate to give the blade a chance to sever the fibers.

Very cool jig. As far as finding a machine screw the same size as the blade, you could instead buy a precision ground pin the correct size. They can be bought in SAE and metric in .0005" and 0.01mm increments. Just measure your blade with a pair of calipers.

1 reply

Good tip, but be sure to measure the kerf width rather than the blade width. The blade flexes and wobbles just slightly so the kerf will be just that little bit wider than the blade tips are. Though to be honest, finding a screw, bolt, L bracket, thin wedge of wood, etc, to fit, is probably easier anyway.

Excellent jig, I have been looking for something like this for a long time as dado sets are impossible to get by in Europe as they are illegal to use.

1 reply

Thanks perhans, I hope it works well for you!

Excellent jig. I've been putting off purchasing a dado set, and this will allow me to put it off even longer.

BTW, I normally avoid video instructables, and seldom watch them the whole way through. I really appreciate the way you sped up many portions of yours - I watched the whole thing!

I always used a wobble dado blade when I made box joints. I have a nice stack set now, but I have not used it yet to make box joints with. Stacks really do not clean the bottom out quite as cleanly as wobble blades do. I am not sure how much of a factor that is going to be if I ever use my stack to cut box joints. But I imagine it might make it a bit harder to make joints that come together very tightly.

Now as far as super simple goes nothing is more simple than the single alignment pin jig

4 replies

Yep that is about as simple as it gets...but you need a dado blade for that jig too. This jig is great for those of us who don't have a dado blade at all.

You could just stack up a few blades on your saw at the same time and make a dado cutter. It is not rocket science. It was what I did when I first started out. Be aware that dado sets are typically smaller diameter than your regular blades. As you generally do not need the depth of cut that you do with your regular blades either. So if you have a bunch of 7.25 diameter blades you can use those to make your own dado stack.

My European made saw only has space for ONE blade. It will not let you stack blades on the arbor! So a great jig! I have been toying with ideas but this obviates all of them. Thanks

Yes you can...but I think you are missing the point of this jig.
The idea was to be able to create accurate fingers with a single blade. Not having to add, remove or change the width of a dado stack makes this a fantastic option. Many woodworkers who already have a dado set have since built this jig, simply because it saves them the set-up time which comes with other methods.

Personally, I only have the one blade for my saw so stacking multiple ones up is not an option. Changing blades on my saw is more hassle than it's worth too. Also if I wanted to buy multiple blades to stack them myself, I'd may as well shell out for a dado stack anyway.

This jig is free, easy and accurate, and works perfectly with a single blade.

this super great for people that live countries were dados are banned..

1 reply

very true, lot's of europeans are happy with me right now :-)