Instructables

Box (finger) joint jig

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This instructable is for a box joint jig, which is necessary for this particular carpentry technique. I made it at TechShop in Menlo Park (http://techshop.ws). I needed this tool so I could create a box joint (also sometimes called a finger joint) using the dado stack bit on the sawstop table saw.

A jig is needed to easily cut 1/2" "fingers" and equally sized spaces in the end of a board. Using this tool will make those cuts clean and efficient.

The box joint is an alternative to the more popular dovetail joint. An interesting point that the box joint is stronger than the dovetail joint, and does not require the custom dovetail jig. Instead, you can create this one with scraps and belt out box joints all day long. Strength test was done at http://woodgears.ca/dovetail/index.html.


 
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Step 1: Parts and Tools list

Picture of Parts and Tools list
To create this instructable, you'll need the following parts:
- Wood scraps - ideally some 1x12 and 2x4 scraps - length will depend on your table saw, but two feet long should be plenty.
- Wood screws - 1 1/4" (at least 14)
- Wood glue

You will also need the following tools (all of which are available at Tech Shop!):
- Table saw with standard blade and dado stack bit set
- Mitre saw
- Power sander
- Power drill
- 1/8" wood drill bit
- Phillips or flat head bit, as required for your wood screws
- Carpenter's combination square
- Pencil

If you're building a jig, it's assumed that you already familiar with the above tools and parts. That said, this is an instructable, so I'll go into some detail as necessary. Please comment your corrections.
Awesome instructable. Just what I've been looking for to make a case for my next projects.
Thanks a bunch for sharing.
Tagwatts12 years ago
If this jig is secured and clamped on a router table, would it not work as well with a router? At present I do not have a table saw to work with, but I do have a router and a Miter Saw. I have a other saws and I think I can still make the cuts on the wood.
A router attached to a router table should be fine I would think. just be sure to use a good bit. i find that on the router, a spiral up cut bit works best as it slices wood and doesnt rip it like a regular rabbit or dado bit would.
zacker1 year ago
I really like this jig. i got a plan off the web that uses your saws Miter gauge and you just screw a piece of scrap 1x4 or 1x6 to it and then do this same thing with the 1/2 stick for a spacer but I like your version better because the thing that ruined my last project (wooden dogs toys toy box) was that 1/2 way through cutting the boards, i knoticed the miter guage had loosened and wasnt set at 90 degrees no more... that stunk. I had to cut off all the ends and then i got mad and just used dowles to join all the pieces with oak dowles. looks good anyhow. But, your designe is nicer. its more like a miter slead with out the miter. very nice, plus i like your use of the second spacer.
vincent75202 years ago
Great job ! …
It's simplicity and almost foolproof idea ("almost" as fools can be very creative) makes it one of the best idea (maybe the best) I've found on the net for a box joint jig (and there are a lot of them ! … ).

However as a foreigner I have trouble to know what exactly is a"dado stack bit set" as stated on the list of required material.
… 
Is it the two blades contraption that is shown on your table saw ?…
If not how this two blade system is called, and is it something "homemade" (if so how did you make it ?) or is it available on the market (a link would be absolutely fantastic) ,…

Thank you again.
Nick.D2 years ago
That's a very creative (and dead simple at that) way to make sure your spacing is correct. I like it!
mistermocha (author)  Nick.D2 years ago
Glad you like it so much!
rimar20002 years ago
Very interesting.

I should try to put two or more equal cutting blades in my hand grinder, for make these unions in my homemade cutting table.
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