SuGar SG1 acoustic guitar build part 43: Preparing the back braces and graft

In this episode I discuss how to brace the back of the guitar, and the particular properties of the wavey grained walnut board. I cut the spruce braces from split stock and glue up the cross grained back graft from offcuts of the sound board.
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[@w.l.h.]

Haha. I don't think I'd ever heard the "Freedom units" dig before. That's a good one. 😉

[@walterrider9600]

thank you Susan. the back is stunning i like the bottom most .

[@bentyreman5769]

having got a book on building an acoustic guitar for Christmas, your video series is quite an inspiration, bring on the next video! I'm hooked

[@garymiller1216]

a very delicate piece of wood clamped between two straight pieces with only a fraction sticking out would assist in adding strength in order to aid sanding with a leveling beam along the length, great informative video as always.

[@ashfinlayson]

Someone got a posh new bandsaw for Christmas :D

[@Fazman81]

I say leave the grain it is visually very appealing. I dont think it will affect the sound that much. That is mainly the tops job. Heck Torres built a paper mache guitar and according to accounts it sounded great.

[@trentjpyt]

With 4 ladder braces on the back you are going to end up with a non-live back. Basically the back resonance will be diminished to the point where they do no couple with the rest of the system . It should however help your projection by not losing energy to the back. So I would include the high figured grain you like. Oh and for a small glue up like that, I would recommend using tape. I first saw it on a Nelson Guitars video (kzbin.info/www/bejne/bpbMpKGCeLV4jLM) and regularly use it when joining bookmatched headstock veers on any small fiddly glue ups that only need a small amount of pressure. Finally, another good practice is to have as little blade exposed on your bandsaw as practical. Quickly turning your fence into the lower orietation would mean you could lower the upper guide for safety sake. Just my 2c and again recommend the Gore/Gillet books to you. Thanks for another enjoyable vid

[@SusanGardener]

I did wonder whether 4 braces was overkill, although you’ll see in the next video that the main monopole mode (without the braces) only involves the lower 2 braces. I’d like a live back - maybe I can still achieve that with shaping the 4 braces.

[@drumgerry]

Can you guess what I'm going to say Susie??!! Haha - yes. Gore/Gilet books! You may change your mind on the ladder braced back thing once you read the Design book. Sneak preview - Trevor uses a hybrid ladder/radial back bracing system to get a live back. Panels are not thicknessed to a standard dimension but thickness is tailored to the actual wood you have using various equations which incorporate the material properties of that wood. I wonder if you'll be saving such things for future builds as the properties of that back panel may, as you appear to suggest, vary wildly from area to area. Don't know. I'd be inclined to use the straightest grain portion of the panel just for the stability and longevity of the instrument. Also regarding the back graft. Probably easier to make a series of shorter pieces that overlap into the footprint of where the brace will go. Then you can trim them for a perfect fit to the brace with the back graft in situ. Also I profile the back graft pieces to a large extent before gluing them on as it saves a bit of bother doing it with very little clearance once they're glued on.

[@daveb2182]

Hi Susie could you do a video on neck angles in the solera. I have made my first guitar (flamenco) and am very pleased with it but the bridge was to high. I'm on my second flamenco now and would like it spot on. Any tips would be great. BTW the first one had 6mm shim under the neck in the solera

[@SusanGardener]

Could the shim be the reason the bridge was too high? I can talk about soleras in 2 videos time as I’ll be bracing the top - a solera and a radius dish are very different things as the edge of the guitar in a solera is planar and the area around the neck is flat. I’ve never made a Spanish guitar, but I have been reading up on them.

[@barryducret1052]

The grain DOSENT turn by 90 degrees, it is because it is the rings of the tree that are seen at an angle of 30 degrees or so. Consider cutting a tree across the grain, the grain appears to go in a circle but this is not so, because the grain is seen on end and not going around the trunk of the tree. The grain of the tree isn't because of a suden bend in the trunk but perhaps because of a divided trunk or branching off of the tree or perhaps it is a crux of the tree.

[@willmorrison1022]

Really interesting piece of back wood. It's unfortunate how often the best looking part of the wood is the worst from a survival standpoint, as well as finishing. Those grain changes can suck up lacquer in a totally different way than the rest of the piece. Don't ask me how I know. Just an side, I frequently practice while I'm watching videos, and have the subtitles on so I can tell what's going on. When you're not talking but are using the band saw and it's whining, the subtitle says "MUSIC". It seems to know how I feel about the sound of a well tuned band saw!

[@esa062]

Does the actual grain direction turn that much? The surface pattern doesn't necessarily follow grain at all. If it does, then that piece is from the base of a large branch and the wood should be extra tough.

[@ColinWatters]

Perhaps the grain of the back graft should change to compliment the changing grain of the back board?

[@SusanGardener]

It’s supporting the joint rather than the grain (unlike the side braces)

[@petemclinc]

I think I would have shipped lapped or half lapped those back graft ends verses butt joints.

[@petemclinc]

Why the hell would you do that? Totally unnecessary, Susan is gluing long grain to long grain, that would only make the pieces thinner at the ends and possibly weaker. You dumb ass!

[@petemclinc]

Who are you calling dumb ass, asshole?

[@petemclinc]

Who do you think shit for brains.

[@petemclinc]

Now-now boys lets try to get along and play nicely...

[@hmarkison]

My question has always been, with most guitarists holding the guitar against their body, damping the back, how much of a role does the resonance of the back really play?

[@SusanGardener]

Ervin Somogyi suggests building according to whether the player will be sitting down with the back free to vibrate, or played standing with the back held against the chest. He builds both reflective backs and resonant backs. My feel, based on guitars I’ve played would be for a resonant back

[@hmarkison]

@@SusanGardener - hard to argue with Somogyi...

[@Fazman81]

I think you need to know if the guitarist you are building for is a big guy like me. If thats the case the back will be dampened whether he/she is sitting or standing. Lol

[@hmarkison]

@@Fazman81 - at the end of the day I don't think much about the back. It will be two or three more lifetimes before I can even figure out the top...lol.

[@shawncharton9416]

Do some research on how the front and back of a violin vibrate. Put the opposite grains in whichever bout will vibrate best. I'm guessing the horizontal pretty part belongs in the top bout and will enhance the higher vibrations.

[@SusanGardener]

I’ve already cut the back out - it looks pretty, and I think it will vibrate well - next but one video.

[@willmorrison1022]

I don't think that's all that applicable in this instance. Between the different method of sound production (the bow vs fingers or a pick) and the sound post tying the two plates together, there are too many differences. Not to mention, the arching of the violin back and sides as well. If this were an arch top instrument, it would be better, but still not the same.

[@shawncharton9416]

I Don't disagree mostly but your points go more toward this instrument not sounding like a violin. If there's vibration of the back - and many think it is so negligible that this doesn't matter at all in guitar construction - then my point applies.

[@willmorrison1022]

@@shawncharton9416 But the means of string vibration is different. Between the bow and the sound post, it's a very different animal. Ever play a guitar with a sound post? Last one I heard had NO projection, and sustain was almost nonexistent. Kind of like a plucked violin. Of course, there is vibration in the back, but it's not a huge factor, from what I have read. What is probably more important is what note it's resonant frequency is compared to the top. In that regard, yes, the two are very similar. But I suspect the back in a violin (or shall we say bowed instrument) is far more important to the over all sound of that instrument rather than that of a plucked one.

[@shawncharton9416]

Yes, dear.