Plans for my Advanced box joint jig are selling well, and I’m pleased that so many of you like the design. It’s a fairly innovative way to cut box joints (I’m putting modesty aside here), at least I am not aware of any other that works in the same way. The current model is the result of two major design revisions to make it easier to build without sacrificing functionality. There’s a point where further revisions may not result in significant improvements to the design, and it’s better to leave well enough alone. I thought I was at that stage with this one, and for the most part that is true, except…

I recently got an interesting idea to solve the division plate / locking blade problem: some potential builders are intimidated by the idea of cutting out the metal and making it accurately.

Basically, I was trying to come up with a different way to cut the division plate and to make the notches “V” shaped as opposed to rectangular. The advantage of a “V” shaped notch is that it would be self centring, and this would eliminate the play between the locking blade and division plate. In my mind, I likened the cut profile to the threads on a bolt, and that’s when the idea occurred to me that rather than cutting a separate metal plate, I could use a piece of threaded rod as the division plate. The locking blade could be another short piece of threaded rod that would swing down and mesh with it:

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Roughly done, but it works splendidly!The rod parts are glued in with slow set epoxy, which is more than strong enough to secure them.

I think it’s worth a design update. This update will be in the form of another version of the jig that uses the different advance mechanism. The advantage to this mechanism will be that it is easier to make because there are no parts that require special machining. There is a small trade off though, but for many this will not be a problem. There are still some details to work out, but I believe it can be ready soon.