Single Blade Box Joint Jig alias digital box joint jig

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Project by George_SA posted 08-17-2015 06:58 PM 11065 views 23 times favorited 7 comments Add to Favorites Watch

I saw the idea for a single blade box joint jig on the website. He has a SketchUp plan Which can be downloaded as well as an instruction video.

I deviated a bit from his plan as I reused my Digital box joint jig sled for this build. The principle behind the jig is quite simple and can be implemented on various platforms. Although I used a digital caliper on the old jig it is still an analogue jig which has it’s own problems with repeatability. With this jig repeatability is quite easy due to the digital nature of the spacer blocks. I used masonite which is just 0.1mm thicker than 3mm kerf width of my blade. Any material can be used for spacer blocks as long as their thickness is consistent.

The first block on the right hand side is stop block for the pin which can be varied in thickness to get the starting point just right. It can be made thinner on a disk sander or playing cards can be added as shims to make it thicker. Fortunately mine was just right and needed no further adjustment.

The secret of this jig is that the pin you use must match the blade’s kerf width quite accurately. I used an old 3mm twist drill bit which works perfectly for my blade.

I also incorporated a clamp on the slide to hold the wood in which the joints are cut. Another modification that I made is a screw clamp on the left end to keep the spacer blocks nice and tight.

The other advantage of this type of jig is that it is quite easy to make variable pin widths. There is a video on his YouTube channel that explains the procedure.

My first test joint came out quite well (see last picture).

-- Sometimes life gets in the way of one's woodworking :)

7 comments so far

View ZAGREB's profile


1276 posts in 2616 days

#1 posted 08-17-2015 07:32 PM

very simple and useful box joint,thanks for sharing

-- bambi

View Dutchy's profile


3938 posts in 3135 days

#2 posted 08-17-2015 08:29 PM

Till now two times favorite.

Simple system. And I like to make things as simple as possible. And therefore: I like your box joint. Well done. I hope you will have a lot of benefit from it.


View kaerlighedsbamsen's profile


1354 posts in 2679 days

#3 posted 08-18-2015 06:57 AM

Super clewer system. Liek the simplicity of it. I suppose the spacer blocks can be rotated to make different sized joints?

-- "Do or Do not. There is no try." - Yoda

View George_SA's profile


436 posts in 3179 days

#4 posted 08-18-2015 01:24 PM

Thanks for the nice comments.

Yes, the spacer blocks are 30mm x 40mm and are meant to be rotated to get the finger width sizes you desire. The nice thing about it is that you can vary them in increments of 3mm. You can make 3 , 6, 9, 12 mm etc spacing (in increments of 3mm in my case, but the increments will depend on the thickness of your spacer blocks you use) and you can also vary the sizes of the individual fingers. The nice thing about it is that you don’t have any fancy setups to do it. Al that you do is to flip the spacer blocs up or down.

-- Sometimes life gets in the way of one's woodworking :)

View Sheisserick's profile


124 posts in 2811 days

#5 posted 10-10-2015 06:19 AM

Nice build

Thanks for linking to your version. I can see you also made some of the same alterations to the woodfathers version.

Your spacerblocks look like “hundolit” subroof woodenfiber? Be careful they dont swell in the humidity.
Edit: Just noticed you like in South Africa. I couldnt trust woodfiber, with our climate here in Denmark.


-- I doubt, therefore I might be

View George_SA's profile


436 posts in 3179 days

#6 posted 10-10-2015 05:38 PM

Thanks for your comments. The spacer blocks is an artificial fibre board. Here in SA we call it masonite. It is quite stable and up until now I have not had any humidity problems with it. The beauty of this jig is that if that problem should arise, it would be quite easy to switch to spacer blocks made from something else.

The reason why I used the masonite fiberboard is that it is just thicker than the 3mm kerf of my saw blade. That gives quite a lot of flexibility iro finger widths. I would usually stack them 2 per finger to give a 6mm (1/4inch) width fingers. The other day however I used the single for a 3mm width fingers for a frame that I made and it worked out quite well

-- Sometimes life gets in the way of one's woodworking :)

View TheWoodfather's profile


117 posts in 2652 days

#7 posted 11-06-2015 01:11 AM

That’s awesome George, I hope it’s giving you great results!
Cheers, Mario

-- - A daddy that loves playing with his kiddies and his tools!

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