Each of them had their merit, but they only solved 1 of the 3 problems that I want a brace jack to address – namely having a way to adjust the outward clamping force. The other two problems I realized needed addressing are putting the brace jack into a position and having it stay there before the tension is adjusted, and one handed operation.

My initial prototypes of brace jacks were built with a variety of materials at hand: copper, brass, wood, nylon. They were spring loaded so they could be positioned where you wanted and stay there. The problem was that the amount of outward pressure was a function of the internal spring strength and was not adjustable. I might have known a guy that cracked the top of a classical guitar because the spring tension was too high.

About that time I acquired a 3D printer, and started working on the problem of adjustable outward force, but the first prototype lacked the ability to be positioned in a fixed place before adjusting the tension. At one point I went completely off course and created a R2D2 looking brace jack that would extend posts from both ends at the same time like the old turnbuckle style brace jacks. But, hiding behind R2D2 is a copper/printed plastic brace jack that finally incorporated a spring for positioning and a tensioning thumb nut.

That was almost what I was hoping for, but I realized the plastic I was using in my 3D printer for prototyping was not strong enough to replicate the brass spring release mechanism. That led to various prototypes that had a “bolt action” type release, an internal thread release, and in one case no spring release. (The internal spring is compressed by pinching the handles on the top and bottom posts together.) They all worked but just weren’t as easy to use as I had hoped.

Just in case you thought there was a smooth transition between each iteration, here’s a pile of “almost right” scrap I generated. Lots of “doh!”s here.

So what’s the “?” at the end of the timeline? I was wondering if anyone would ask.

Is this finally the one I’m happy with? Well almost. I realized there is a 4th requirement for a brace jack

that I hadn’t addressed yet: the requirement for different length brace jacks that are small enough to fit

between the braces of a Gibson LG-0, large enough for a jumbo, and everything in between. I think I’ve

got a solution that minimizes the number of different size brace jacks you would need to cover most

guitars. Stay tuned for a post to Loothprints.