Box-Joint Jig

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Finally getting back to the shop after a way too long hiatus. Won’t explain, but had issues.

Anyway, I am attempting to make my first ever box-joint jig with:

  • sliding miter gauge
  • 3/4" MDF
  • 1/4″ × 1/4" DIY hardwood stock
  • A 1/4"-3/8" Freud Box-Joint Blade

First attempt, on scrap, was a complete failure and would not join at all. Second attempt joins, but I want to know how loose is TOO loose of a fit. On the end of a ~2-1/2" wide piece of hardwood, most of my joints have 0.012" to 0.015" gap (about 1/64"), when assembled into a box corner. FYI, the joint can fall apart via gravity if allowed.

Will TB3 basically make this a non-issue? Or do I need to ‘rinse and repeat’ for a tight/snug fit?


I am not an expert but I think 1/64 is pretty good.
I am thinking when you apply the glue the fingers are going to swell a tiny from each side.

Abbas, Castro Valley, CA

Forgot images of test joints in white ash


Digging into my Gifted WW Library, I just found plans for a “micro-adjustable” box joint jig in ShopNotes Vol.2 No.8 March 1993.

This will be a small project in its own sake, but will be well used in the future. NOW I will be able to eliminate any/all gaps!… 8-)


That’s a bit more than I thought:)

Abbas, Castro Valley, CA

I built a similar jig for my router table. I have a different jig for 1/4" and 3/8" wide fingers. I did incorporate the fine adjustment for the finger width. I find that I like a snug fit for my joints. Also, I found the setting will be slightly different for different kinds of wood.

Good Luck and let us know how it works out.

That’s OK Mike, I’ve taken up where you left off, I’ve not been in my shop for a month, just taking a break. Nice box.

Randy - If I'm not on the computer than I'm out making sawdust.

The jig I first made was a very simple, cross your fingers and hope you got it right kind of jig. NO adjust-ability. I’ll use for my first box, a Hoppes gun cleaning kit, that I want to change from its OEM cheap plastic to wooden.

My next project will be the above “micro-adjustable” jig, once I get to WC and/or HD and pick up the needed bolts, inserts, and knobs.

Here is the simple jig. You can see where I had to attempt it twice (by the cuts). Not very substantial and will not last long IMO, but will work for now:


Mine is virtually the same as yours. It took a lot of trial and error to get right. Just keep plugging away. My “micro adjust” is my mallet. ;-)

Losing fingers since 1969

(nice to see you back again… hope all is well!)

Toxins Out, Nature In - body/mind/spirit

Thanks MsDebbie!

And BTW, I did finish up on my planer table project/blog. It was the first blog posted here on WWWeb 2 years ago (bottom of blog page 77). Yeah, I’m feelin’ a bit guilty… ;-)