Super Simple, Single Blade Box (Finger) Joint Jig





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

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.

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.

Thanks perhans, I hope it works well for you!