Box Joint Jig

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Project by Wingstress posted 2021 days ago 6924 views 39 times favorited 9 comments Add to Favorites Watch

I was at a woodworking show in Springfield Ma a couple weeks ago and there was a guy from woodline who was trying to sell a box cutting joint made out of delrin. It seemed really simple. It was basically just a square dowel sticking out of a flat plate. So I went to home depot and bought a .25-inch hardwood square dowel for 77 cents and then put a dado in a piece of scrape plywood and then glued the dowel in place. I then made a push block out of plywood and a 2X4. I used a bronze gauge block to set the groove width and started cutting. It turned out to work pretty well. I had to put a bunch of screw down knobs to hold it down because the plywood had a slight bow that affected the depth of cut measurement. After a few knobs, it laid nice and flat.

-- Tom, Simsbury, CT

9 comments so far

View FlWoodRat's profile


732 posts in 2534 days

#1 posted 2020 days ago

Wing, nice looking jig. Thanks for posting it. I’m going to ‘favorite’ this one so that I can build one for my router table.. LOL, after I get that done. It’s on the list too.

-- I love the smell of sawdust in the morning....

View HallTree's profile


5661 posts in 2392 days

#2 posted 2020 days ago

Nice job. I suppose you could make it to adapt to other bit sizes?

-- "Hold on to instruction, do not let it go; guard it well, for it is your life" Solomon

View croquetman's profile


120 posts in 1946 days

#3 posted 1923 days ago

I don’t see the sense in the dowel being so long. Is there a reason why this is designed that way?

-- Whatever

View Wingstress's profile


328 posts in 2140 days

#4 posted 1923 days ago

No reason really. It just made it really easy to make. One groove down a piece of plywood and then a square dowel bought at Home Depot. Its nice having it long on the back side so you can move the fence back far enough to clear chips while keeping alignment. I guess, it allows you to have virtually limitless thickness of wood as well, but I’ve never cut thick stock with it…

-- Tom, Simsbury, CT

View Derby's profile


27 posts in 1898 days

#5 posted 1897 days ago

Great idea! I wonder if I can adapt it for use with my router, mounted under a cast iron TS extension wing. Maybe I can use the clamp bar from one of those plastic featherboards and the miter slot???

-- "Lumber is just sawdust in 'solid' form!"

View D1st's profile


289 posts in 1665 days

#6 posted 1239 days ago

What kind of bit is that? Spiral upcut or downcut? Thanks


View lanwater's profile


3076 posts in 1559 days

#7 posted 1239 days ago

The idea is similar to the rockler jig.


-- Abbas, Castro Valley, CA

View Wingstress's profile


328 posts in 2140 days

#8 posted 1238 days ago

Hey D1st, If memory serves, its a down spiral, carbide router bit from white side. I’m not sure if it makes too big of a difference. The most tearout that you’ll have is on the back side when you exit the piece. That’s why its important to have a zero clearance backer board or in this case a push fence.

-- Tom, Simsbury, CT

View chrisstef's profile


10621 posts in 1631 days

#9 posted 1238 days ago

well done … added to my favorite list of projects.

-- "there aren’t many hand tools as awe-inspiring as the #8 jointer. I mean, it just reeks of cast iron heft and hubris" - Smitty

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