CNC Box (Finger) Joint Box

OK I have had this in my head for a few days now so I thought I would sketch it out. It could be milled out of aluminum right on our machines. You would have to carefully drill and tap a pair of holes on the front of the Shapeoko. It is adjustable so you could cut at angels other than 90*. I just did this in Tinkercad in about 45 minutes so it’s just a little rough right now.

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Very cool design! I actually considered something similar, but decided to forego the angular adjustment — my idea was to have grooves cut with a V bit as you’d see in a Hirth coupling to align it at 1 degree increments, so it needed a two-sided operation.

Arguably you’d only need 5 degree increments — 15 for Tailmaker, 45 for 4 sided boxes — but I suppose if folks want to do other style of boxes or bowl blanks you’d want to facilitate those.

Here’s a sobering post on the consequences of a 1 degree error compounded 16 times:

6,251 votes and 336 comments so far on Reddit

Okay, we’ve got four good pieces cut, now to mount them, then cut the joints (twice):


Can’t wait to see the parts after they are cut.

I meant no disrespect to what you are designing. I just got excited when watching this guy on YouTube doing crazy finger joints on a CNC.

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None taken, I’m mostly a very prosaic person, w/ a minimalist design aesthetic which was usually criticized as being too austere in college critiques.

It is really ingenious some of the joints folks have worked up — the really interesting thing is how old some of them are such as Knapp joints (which dates back to just after the American Civil War).

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I will be up for the book deal

That guys glue approach seems to mimic how I’ve seen some people solder (the bigger the glob, the better the job). Still though, I love seeing creative joinery. Trying to figure out how to do my next box and may try my hand at something like that eventually. Thanks for posting that video Chris.

And Will thanks for running through the tutorial!

My pleasure!

(and my thanks for the interest in the book to @Gerryattrick )

I’m afraid I had to pull an all-nighter to finish paging a book at work so as to not fall behind schedule, so no cutting this evening — knocking out a quick tutorial at: Using textures to create a rustic letter

Hopefully I’ll do a test cut and then cut the boards which I’ve got mounted tomorrow — did get the file for the joints drawn up at least.

Finally got the cuts done — had to do two boards at a time, and somewhat messed up on the depths — I guess I should add a surfacing pass to ensure I’m getting them consistent (and may need to recalibrate my Z-axis):


And I believe we can put this one in the success column:

I will be cleaning up the files a bit, then posting them to cutrocket, then getting to work on the Kickstarter


ok how do i use OpenScad? lol …

You would need to:

  • download OpenSCAD — you’ll need a Development Snapshot so go to: and download the appropriate version for your computer
  • download the OpenSCAD file (hang on a bit while I post an updated one — there’s an old one further up, but it may have some errors/problems)
  • open OpenSCAD, hide the editor, then disclose the settings in the Customizer (should be viewable on the right) and adjust them as desired until you get a box you want. You could then save the preset under a suitable name (use the [+] button to get a new name, then press “save preset” to save — this will make a .json file — post that here and I’ll work up the SVG file and post it — eventually I’ll have a better system for this.

Wow! That’s cool… I have not downloaded yet, but will we eventually be able to make an svg file ourselves from it or a vertical file or cc file?

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Lol my wife says give him more than that for the kick starter lol

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Yes. The way it currently works is:

  • run OpenSCAD and adjust settings — when you save a preset, that saves them to a JSON file
  • run a LuaLaTeX/METAPOST file which imports the settings from the JSON file — the creates a PDF (currently) which has the geometry for cutting out the box as shown above — note that I haven’t made this available yet — it would require installing MikTeX, and I’m not sure I’m going to stick with it.
  • open the PDFs in Inkscape, save out as an SVG
  • import SVG into Carbide Create and assign toolpaths

Worst case is I’ll do that for folks and put the files up on Cutrocket or the wiki or something — I’ll put the lualatex file up somewhere as well, but it’s a bit involved to get MikTeX running, and it doesn’t make for that nice an interface. METAPOST, which is the graphical programming tool I’m using can write out SVGs directly, but running it directly is even odder.

I’m hoping that what I can work up is a program (say a LiveCode file) which opens OpenSCAD and works as an external editor (it’ll probably change the JSON file) — adjust that until you get the settings you want (I want to use a separate program from OpenSCAD so that things such as changing dimensions will work properly and one can do data validation and so forth) — once you’re satisfied with the preview of the design in OpenSCAD one could then write out a Carbide Create file complete with toolpaths.

Or, maybe we can get the OpenSCAD files hosted at Libre3D so that they’re interactive, and the site runs lualatex in the background so that it makes an SVG — still working out the details based on how much money comes in.

Well I can already do the files then as I have silhouette pro and that will convert to svg anyway, and I have Vcarve so it will work
For me ok…by the way I donated to the cause $50 I hope others are just as smart as me :slight_smile:

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Latest version posted below

Please let me know how it works out and if you have any difficulties.

Once you’ve got the box file read you’ll need to make a fixture to stand the boards on end and cut the joints — there’s one here: CNC Finger Joint Box and in the following couple of posts.

Well thats a bummer the development package for mac ends up as a 404…?how do i get it then…

If we look in:
It looks like: might work.