Thread: Box joint jig

Looks good Fuzzie. Great job

I made Ed Stiles jig. experimenting now with various options. You are right, the glue up is a pain

My biggest problem is getting the spacing just right for the fingers and that is obviously because it is a screw advance jig and everything must be an exact multiple of 1/16th. Turns out my blade was the problem. Good quality 1/8th but even after getting it flat top ground it was .129 inches not 0.125. Solved that now though by carefully taking off some kerf by dragging the blade over a diamond plate. Now kerf is 0.126 which works well, just leaving space for gluing up.

Lots of tweaking needed on these jigs

Thanks Bob. I chose to build this jig because it seemed fairly simple and I had suitable sized scraps on hand, mainly brushbox. Combining it with the auxiliary jig to thickness a spacer piece makes the setup quite quick and usable with any size blade or thickness board. I only intend to use it for utility boxes so I haven't invested in any special blade and the bottom of the slots might look a bit rough on close inspection. It does become a bit tedious making the multiple passes required to cut each slot. Upside is, if I ever make a router table the jig can also serve dual service and be used with a router to cut flat bottom slots.

I would be very happy though to stumble across some suitable sized cast iron fingers that could be used to replace the soft steel mending brackets.

It's so humid here at the moment, the first coat of finish on the table I'm building hadn't dried enough overnight to sand back for a final coat, so not having anything better to do I decided to give the jig a tryout on some scraps leftover from the table build.

First problems I had are all to do with humidity. It's been 80-100% humidity here for the last week or so. The runner for the spacer jig was binding in the mitre slots and the other bits weren't really sliding nicely. I shaved the runner to get it moving and probably should have waxed everything else for ease of use, but I didn't.

For the exercise the finger width was to be the same as the thickness of the material. Here the material thickness is being shaved for use in setting the main jig. I couldn't see any way to use the blade guard doing this, but kept fingers as far as possible out of the way with a long push stick.
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The auxiliary single blade sled alongside the standard woodsmith jig.
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With the Woodsmith jig straddling the auxiliary jig and using the spacer to set the left/right stops and the finger spacings.
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Next set the blade spacing to the fingers with the jig pushed fully to the left
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First pass on test pieces. Seemed to be an ok setup. Bottom of notches rough though and needed cleaning to fit better.
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I attempted to gang up two sides to notch at once. This was actually a bit flaky since it was hard to hold every thing in place securely and keep it square. Also sliding the sled left and right was a bit rough and I think the soft metal fingers flexed a bit while being straddled.
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End result.... not very good. I lost track of which side I had started on and cut the first slot on the next set of sides with the wrong offset.
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Not foolproof and definitely in need of some sort of additional fence to help keep things aligned while moving the sled back and forwards over the blade. A deeper leading ledge would also be beneficial to support the thickness of two sides being notched at once.

As they say, two steps forward.....