All About Back Bracing

What purpose do they serve, why are they designed the way they are, and which bracing patterns are "best".
These are the conclusions I have come to over the last 9 years of making guitars. Things that I believe do and don't make a difference to the sound - this is in addition to the nuances that different woods used for backs contribute to each guitar's sound. I hope you enjoy!
-Zach

[@rodparker4514]

.Lovely back wood young man .Option.Leave the braces a little thicker at the ends and cut a mortise right through the sides .Make sure they are small enough to be covered by the bindings of course .Seeing the perfect joinery is worth it for me .More please .

[@redtreecollectiveguitars]

Thanks, I do that with most back wood species, but not maple (like this one) because I want the brace ends shorter and more flexible. I have a jig that goes around either side of the brace ends when I’m carving that I carve down flush with. This makes the notches in the sides as simple as using a router that’s set to the matching depth. Further, all the notches going into my sides are the same depth (except for the upper transverse brace on the top). So the same router can be used for all notches in the sides and the reinforcing patch above the upper transverse brace that spans across the neck block extension - no accidents going too deep where binding won’t cover it, all clean notches with no broken kerfing pieces and super simple and quick setup. Works great. 👍🏼

[@BradExample]

I love your videos. Even tho, i have never built a guitar, i love watching you do it.

[@redtreecollectiveguitars]

Thanks Brad! :) -Zach

[@DarrenForbes]

These are top notch videos.

[@redtreecollectiveguitars]

Thanks Darren! I thought KZbin needed more content on the science of guitar making. There’s not much out there! Hopefully it’s helpful for other guitar makers. :) -Zach

[@macdaraofaolain]

Great video!!

[@redtreecollectiveguitars]

Thanks Macdara!! :) -Zach

[@markgrimm3564]

superb work zach what's your thoughts on sealing the inside back and sides with a 2lb cut of shellac to combat humidity

[@zachlefebvre4825]

Personally I don’t think it has much benefit at all so I don’t do it. Humidity will still penetrate into a shellacked back just slower. There are also sonic benefits to leaving the inside surfaces kinda “rough” as opposed to glossy.

[@alannkevin]

So the rule of thumb is that the whole board needs to sound exactly the same all over? Maybe a G or F# for top and A for back?

[@treehouseguitars]

Honestly my approach isn’t based on tapping so I couldn’t say from my experience that that is a rule of thumb, however I have heard that many guitar makers aim for a similar rap tone throughout the plates. The note that they ring at, on the other hand, shouldn’t coincide with a note of the scale because that can cause issues with wolf notes/sympathetic resonances. In the end you want to tune plates in between notes of the scale if at all possible. Once the plates are glued to the sides and the box is closed a lot changes so what I’m referring to is the final tuning. Free plate tuning is a whole other thing… which I don’t know a whole lot about and which I haven’t found very useful in my own build approach.

[@alannkevin]

@@treehouseguitars 🤔 now I am not going to be able to sleep tonight 😆, I already glued the braces and the top has a note of maybe B, I am in the process of removing some wood off the braces, but something you mentioned is the “note of the scale”… what do you mean by that? my scale is 25.5

[@treehouseguitars]

Haha, I only meant that the final note shouldn’t lie on a note of the musical scale, like A 440, C#, Bb, etc. It’s actually not as important for the back though and I wouldn’t even bother tuning until the sides are glued on if you are planning on tuning. I don’t tune my backs at all and I’ve never had any issues with wolf notes.

[@treehouseguitars]

Oops, you said your top is a B. So you can try to coax it away from being right on a B to between B and Bb… or you can leave it and it will most likely be just fine. :)