Hi Chris, really enjoy your videos. My thoughts as a structural engineer... it looks like what you are trying to achieve is getting the transverse brace to work as a fixed end beam rather than a simply supported beam (engineering jargon) which restricts rotation at the supporting ends rather than the ends just being pin supports. This will work provided that you get a solid glue join from the end grain (hard) of the braces to the sides, otherwise it doesn't add any bending strength and just adds weight to the brace. Think about how bridges are built where they are tallest in the centre and not so at the ends/supports, Sydney harbour bridge is a good example (note this is a completely different structural method than suspension bridges which do not relate to how a transverse brace works). It is far more effective to add depth to the centre of the brace and rely on the ends as simple supports which do not need to be thick as they act only in shear not bending. I'd be happy to elaborate further if you are interested. Kind regards, Dave
@David Sutherland. Mahalo for those insights. What is the engineering term for a "beam" that is not supported at its ends and instead is just attached (glued) to a plate (soundboard). This is the opposite of what Driftwood Guitars does. Many guitar builders do not "tuck" their bracing into the sides/kerfing. It is my understanding that such an unsupported beam would not exhibit the same properties as a simply supported beam whereby the load is a function of the cube of the height of the beam.
Engineer here too. I immediately had the same thoughts. Structurally, the solution to scallop the brace in the middle does exactly the opposite that it is supposed to do. It reduces the moment of inertia of the brace in the section with the highest stresses and therefore weakens it. That’s the reason why you give your guitar tops and x-braces a radius, because it increases the moment of inertia in the middle of top and therefore makes it stiffer and capable to carry more load.
Really look forward to watching these videos every week even though I have absolutely no business building guitars. You really make it accessible to a guitar player with zero background in lutherie. Just wanted to say thanks!
I'm not a builder, just a guitar player, but this is fascinating to me. I just wanted to reach out and tell you how much I appreciate your knowledge and willingness to share what you have learned. Maybe I will learn something that will make me a better guitar buyer. Lol
Chris I did your mod to my bridge by cutting the slots in the Bridge. Sorry I'm responding in this video, but I'm here now. It WORKED! I believed your explanation, and I had to make my own saw because StewMac is out of the nice ones you recommended. I did my Epiphone Hummingbird which looks great and costs less than 400. It was a bit thick and dull before. It's braces I can see in the sound hole are huge and not scalloped . It was a nice looking but poor playing guitar. Now it sounds like a $600 guitar which is a huge improvement... Thanks from your new fan boy....
Thanks so much! We’re pretty proud of how far we’ve come in a short time. A lot of people complaining because it’s not perfect, but we’re trying our best.
@@DriftwoodGuitars I will never understand people who get on TH-cam and complain about someone else's work or art. They are not on TH-cam presenting their work
In regard to the allen wrench hole in the cross brace and it's strength. Many years ago a friend was a forestry student at Oregon State Univ. They did stress testing on fir beams that showed that the greatest part of the stress was handled by the top and bottom surfaces of the beams. Putting holes in the middle did not affect the strength of the beams any significant amount. :)
Completely addicted to studying this build process…as in watched the first 4 episodes last night finishing around 1AM with a looming 5:30AM alarm for my workday. Great stuff and thanks for sharing so much of your process!
A number of classical guitar builders shape both (above and below the soundhole on a classical) transverse bars similarly, though more lightly. I hadn't reasoned why, but you make it clear. Thanks! Also, some classical builders use a slight arc but at the ends glue "pillars," which might have a similar reason. I have an early Martin D12-20 that was retrofitted with an adjustable truss rod. The transverse brace had been cut away almost entirely for access, leaving the unglued side open. I added a plug, a strap across the filled gap, laminated both sides of the brace, and redrilled the hole. It still needed a neck reset but not so badly. I hadn't thought about regularly sistering that brace, but it makes a great deal of sense. Thanks.
You gave me lots of food for thought. I never really put much thought into that part. I just copy what everybody else does. Can't wait to see how you bring it together with the sides. Good job with the videos.
Having said that, if it is tied really firmly to the sides, it would acutally need to pull the sides in in order to deflect...hmmm. And just seen that the addition of the rosewood makes it the same as a composite beam and will strengthen the brace. Nice...not just decorative.
I see a lot of the comments worried about the hole in the brace. If I am not mistaken the top will also be glued to the neck extension and fretboard right over this hole. That is usually 2 different woods (3 if there is binding) added to the top and the brace and the side laminate on the brace for a total of 5 to 7 different pieces of wood in 5 different orientations around that hole. Probably pretty strong.
Hi Chris, your analogy about the roof beam isn't correct from a structural integrity viewpoint. The ends of a beam only need to resist shear forces, whilst it is the middle of any beam that rely on sufficient depth to resist deflection. It is the centre of the beam that has the most work to do. (You may wish to read Structures : Or Why Things Don't Fall Down by J.E. Gordon). I'm extremely curious about your conclusion and how this may effect the longevity of this amazing guitar build. Loving your vids BTW.
Nice camera work, thanks! You thoughts about the transverse brace are really interesting. My first reaction was negative, but it does makes sense. And, I radiused my transverse brace. Grrr. I see a number of ways forward. On I go!
Great quality video. And yeah why do we scallop the transverse bar. Lol. I think I would leave a hump above the truss hole to retain some strength, but maybe the rosewood is enough.
New rig looks sweet! The slowmo is a nice add as well. As an architect, I can see why you would scallop the transverse brace as the bending stress would be greatest at the center. However, the sheer stress would be greatest at the ends. With scalloped ends, the top would be able to allow flexture at the edges and would therefore it would allow a wave across that section of the guitar over time. If your plan is to lock the top down at that point, the tall edges would def be a better move... My question is whether the radius on the body sides above that brace creates an odd geometry that is flat across the brace and radiused around edges... I suspect its marginal.
Awesome! Finally got to be the 1000th person to like one of your vids. Just starting out on my luthier journey and your channel is gold. When can I come for an apprenticeship? I kid. Keep em coming!
Enjoying this series quite a bit, the transverse brace arguments aren't clicking though. I'll wait until things come together, see if it makes more sense or I can ask some reasonably informed questions.
How to Build an Acoustic Guitar. Episode 5 Hi Chris, thanks for the video. Please kindly clarify the topic in regards to avoiding stress in the top-plate. At 7:50 (on the runtime) you show how once the 35° braces have been glued in-place, it forces a 35° radius on the top-plate as shown at 7:50 when you rock the top back and forth. In a perfect world, (aside from the braces being sanded to conform to a 35° radius) wouldn't the top-plate also have to be radiused to 35° as well before gluing on the braces? I understand this would be a daunting task. The way you explained earlier is that you don't want any stresses in the top because it can inhibite the vibrations. If the top-plate is 'essentially' being "forced" (stressed) into a 35° radius as a result of gluing down the braces, isn't that introducing stress into the top? My understanding is that the top-plate will always want to return to a flat position (0° radius) causing stress. I do hope I explained this clearly. Thank you Chris.
Some food for thought for those commenting about the transverse brace, part of the somogyi style (the book mentioned) is to also butt a 'fretboard' extension into the transverse brace. Basically distributing the load of the neck block intro the transverse brace that is buttressed against the sides/kerfed linings..Also great video, and content
The brace will only be as strong as it's smallest cross-section therefore the truss rod hole will weaken it where it's drilled (this might be why others shape it wider at this point and down at the edges). The lower portion of the brace below the truss rod hole will be in tension when the neck is under load. An unshaped brace would be stronger. It should be pretty easy to model the stresses using CAD to see the differences in the designs.
Not correct, the ends work in shear which do not need to be as big, the centre works in bending where the depth and the outer faces has greater effect than overall cross section and centre penetrations are permissible. This is routinely utilised in many engineering applications
@@davidsutherland1825 That was kind of my point, slimming the brace down in the middle and then drilling a hole is, in my mind, going to create a weaker brace not stronger that a traditional one. An unshaped one will be stronger (even if the strength is not needed). I might model it up in CAD and do some stress analysis.
Doesn't that hole for the truss rod access compromise the structural integrity of the transverse brace now that its that short in the middle? With the string tension pulling the neck, there is a significant amount of pressure from the neck onto that part of the top, that it my thought about it. Looking forward for your explanation.
I'm not a builder (yet). I jam with a builder who made my OM-28k to pre-war spec (he's a devout traditionalist). This instrument can stand right up to his well-maintained prewar Martin collection... However.... he has inspired me to build. I've been acquiring tools. The engineer in me disagrees with your transverse brace design. In industry, I've seen welded support beams made like the traditional transverse, tapered at the ends. The buildings are still standing. Given that the brace is glued to the top (which now becomes a structural co-brace), tapered ends just make more sense to me. But hey, if your design works... go for it. The beauty of all the builders out there is innovation (my friend not included, he wouldn't dare waver from tradition)... I would... I've made electric guitars... but what is a solid body guitar but a plank, with a nice neck.
Looks much better overall vs the old rig. Slow motion and panning shots look so professional! Perhaps there could be less grey/green in the colour grade and something could be done to the autofocus when you do the headshots - it's rather jumpy and noticeable in the background. Great work! And thank you so much for the incredibly useful and educational content!
Thanks guys. I would think that if you're looking for the strongest, lightest beam, the trusty old I beam would do the trick. Maybe laminated with multiple pieces of wood.
With all the extra efficiency you have put into your building, I am surprised you haven't put a taper on the hole to make it easier to find while having the taper guide the wrench to the right location.
Loving the content man! You should do a vid showing your spray booth setup/ guns/ techniques. Would def be interested. I just started using nitro about a week ago.I used water based before, due to lack of a proper booth. Now I finally gave the proper facilities for nitro. Man it's so much better than water based! Never going back haha
We now sell hand selected and resawn Tonewoods on our website! Each piece was found by Chris Alvarado, and almost always has a story to go along with it. Go check out the selection at www.driftwoodguitars.com/tonewood
Loving this series! Very thought provoking video, “Why is it shaped like that?” This is why I love lutherie because of the multiple variables in play at the same time and having to account for them. Correct me if I’m wrong, but your braces (measured in the center) seem to be very similarly sized to the Martin in the video. Is the ½ inch height at the center of the brace about “standard”? If so, your brace is effectively the same strength as a “traditionally shaped” transverse brace with the additional surface area in the ends. This begs the question, if this brace is purely structural as mentioned, why do we bother to “shape” this brace at all? Borrowing from the A-frame roof analogy, those beams are not shaped and are just full sized rectangles. Is it because every other brace is “shaped” that this brace also has to be “shaped”? If maximum strength is our goal and weight is not a consideration, because this bar is the effective boundary of the moving top, then why not just leave this brace unshaped? If we want our sides to be as stiff as possible (laminated sides) and use solid linings for their stiffness. It would seem that a stiff perimeter is the goal. If the transverse brace is effectively part of the “perimeter” of the soundboard then why not make it as stiff as possible = no shaping/reduction of material? Why is this brace shaped at all? lol. Or is an unshaped brace synonymous with “cheap” construction? If your brace height at the center is the same as a “normal” transverse brace it seems like you have a solution which fulfills both the form (shaping for aesthetics) and function (strength) of a "traditional" transverse brace with the minimal drawback of adding minimal weight to the "perimeter".
As I was following your thought process on making that transverse much stronger, it seemed odd to then drill a hole in the middle of the beam which would weaken it? Is it not the middle that needs to be the strongest part but rather more so your explanation of just tying it to the sides that is more important? Love following the build and aspire to build an acoustic someday!
If you think about a road bridge, it doesn't really matter : the "arch" is making it strong, not the amount of material. Well, on the principle at least ! One suggestion though : what about linking your transverse brace to the side braces ? then you would have a complete Eiffel road bridge !!!
@@jean-yvescabon2892 but the transverse brace isn’t an arch, it’s a beam. And as such, it will be the flexiest where it’s the thinnest. Many steel beam bridges are shaped in a similar fashion to the traditional transverse brace.
A hole in the center is not an issue. Strength comes from depth of section, not the amount of material. As long as the hole is not in the outer 1/3 s and is centered top-to-bottom (on tje neutral axis or very nearly so) its not an issue
Hi, physicist here) Main problem with fretboard over soundboard is soundboard's bending, not moving whole soundboard to backside. Thus, in this place height of the transverse bar is much more important then how one glues to the sides. To be more precise, height and length of those height - to have substantial brace outreach from each side of the fretboard. Nevertheless, this profile provides incredibly rigid structure in those area the affects sound for sure. I think it (could be) good for steel-string guitar, but its too rigid for nylon-string guitar... Also, you could look for train-bridges frames - almost always they have narrow ends and tall middle part. Exactly because those bending supremacy over other movements.
@@DriftwoodGuitars you're welcome! I am not a builder. Just a player but I have been playing for about 60 years and made a point of understanding build methods so I can know what I'm buying and what to look for. Your are an impressive builder and you remind me of David Furch of Furch guitars in the way you approach tone and strength in your guitars.
Based on your explanation of the purpose of the transverse brace, I don''t understand why you carve out the center. Why not leave it at maximum thickness all the way across in order to increase its strength in the center? This would also make the upper part of the top less resonant, I would think.
I think both things , carbon fiber, and dog bone joint make sense and I think you are on to something. Check out against the grain instruments here on youtube he has a unique neck joint also and a sort of acoustic /electric hybrid. I tried to post this on your video of Rhett Shull's guitar but it wouldn't let me
Interesting. First make your brace stronger than drill a large hole through the center and make it substantially weaker. Question: Have you tested your brace's strength? First as a solid brace, then with the hole and no lamination, next with hole and laminated support (one side only) and finally with the hole and two sides laminated? The test results would be very informative and enlightening.
The ribs on an aircraft wing as well as many of the support beams on a bridge have holes in them for weight reduction. A properly drilled hole, should insignificantly reduce strength. I hate Trussrod covers, and the hole is required to access it from the sound hole. The main strength added comes from the extra material on the sides that can now be glued to, and jointed with the sides.
My Laravee got around this by not allowing access through the transverse brace or through the headstock, there's a special, big, curved Allen wrench that they give you with the guitar to reach it, it's a real pain in the ass. I had to get a mirror down in there to finally get it in properly
@@DriftwoodGuitars Aluminum wing frame not a good analogy due to the number of trusses (struts) and material used. Holes in wood are another story altogether. See: building codes re house beams (floor-ceiling joist) and holes cut through. You did not answer my question re testing of your truss in different forms. Just seems counterintuitive to design a thicker brace then defeat the purpose by drilling a large hole through it. (See Gabriel's comment below)
@@0whitestone So you recognize the issue of drilling large holes in small wood braces! Adding the lamination helps but is it sufficient to offset that huge hole in the center? That was my question. I suspect the brace's proximity to the headstock likely offsets flex issues there above the sound hole. Maybe a moot issue?
@@patrickleary2389 My point was actually how inconvenient it is to not have the hole. Every other guitar I own that has access through the sound hole has a hole in the transverse brace, this includes Martin's and 40-year-old Takamine. I don't think it's going to cause any issues because it hasn't on any of my other instruments. I'm going to trust Chris on this, besides, if there's any issues with a guitar you purchase from him, I'm sure he'll honor his workmanship on it.
Why not make it 14-15mm all the way across? Maybe taper it or make it parabolic on the frontside and flat so the neck support can butt up against it. Wouldn't that make that whole area more stable? I see most acoustics have a gap in that area. I build Bajoquintos and always butt the neck extensión to the upper transverse brace. Never understood why they dont do that with acoustics. Those templates are DOPE by the way. Do you have a vid on how you make them?
Interesting transverse bracing. Wondering if drilling the truce rod hole, which looks like it removes about 70% of the material in the middle of that brace, is countering what you’re trying to do here. The rosewood piece adds some strength back, but just wondering..
Another thing you never see in house construction are beams with holes in the middle. If you really want the transverse brace to strong you need headstock truss rod adjustment. But I don’t like that either.
The ribs on an aircraft wing as well as many of the support beams on a bridge have holes in them for weight reduction. A properly drilled hole, should insignificantly reduce strength. I hate Trussrod covers, and the hole is required to access it from the sound hole. The main strength added comes from the extra material on the sides that can now be glued to, and jointed with the sides.
@Dane Nichols: Yes, you do. Go into the basement of a residential construction. You will see this principle being applied: "Code says that you may not staple wires to the bottom of a floor joist unless the wire is 6-2, 8-3, or larger. Smaller wires must be run through bored holes or be attached to a running board.: Plumbing is, also, run through floor joists. Notching is bad, centered drilling is OK.
@@zapa1pnt we were talking about a structural beam not floor joists. You can't drill any size hole through a structural beam. Agreed notching is bad, that is in essence what Chris is avoiding by making the brace thicker at the ends.
@@DriftwoodGuitars, Engineered trusses are made to have space. You have made a truss of sorts by adding the rosewood but the is it would be stronger with no hole at all. Which I agree is hard to do if you don't want to weaken the headstock with truss rod access. Maybe a bridge truss style traverse brace would check all the boxes.
Hi, I'm a structural engineer, penetrations through the centre third of a beam centre are commonplace as the bending strength comes mainly from the outer (top and bottom) faces. Consider an I-beam which has large top and bottom plates with a tiny web in the middle
great video! just a tip, I think you might want to take some time getting your white balance right for the shop on the new camera-it looks like a lot of the blues have been washed out a bit
Hello Chris. Awesome videos!! I'm not a guitar builder but I'm absolutely fascinated. I have a question. I would like to buy a new Bourgeois Soloist. Madagascar back and sides and Sunburst Carpathian spruce top. I can get it for 7K. Any thoughts?
I know this is an older video, but how would you go about making a transvers bar for a guitar with a corner soundhole? Something along the lines of your DaVinci models.
Chris, it takes you 250 - 300 hours to build perfect guitar. What would be minimum in terms of hours for you to build good basic acoustic with no beautiful, but time consuming details ( inlays, binding, purfling, bevels )? Would such approach generate much lower price for still high quality instrument? I have seen video about US guitar maker, stated that they produce one acoustic weekly per luthier.
I wonder if you would answer a question for me, I have some purple heart, some island mahogany, and some black walnut, which would be best for the bridge of an acoustic?
I like the concept in your version of the upper transverse brace. Having been in Construction for the last 40 years it makes complete sense. However there is one aspect that bugs me about it. Your trussrod hole seems large in diameter through what has become the thinnest section of the transverse brace. From a constructional point of view this would be considered a no no. Would it not be better to make say the very centre section of the brace thicker over the centre section to improve structural strength over the area thats been weakened by drilling a hole through it, in a not too disimilar way to the ends of the brace?. The tiny additional weight of this slight thickening would most probably have no effect on tone as the idea is to get the bit of soundboard below this brace to vibrate freely not above it?. Just thoughts...
@ Alex Ryder: Martin guitars use the same 1/2" thick transverse, with a hole in it for truss rod access. By making the 1/2" span shorter, he has made it stronger.
I don't get it - if the transverse bar is not about sound/vibration, and instead about strength and support, what are you still using Spruce? Why not make it rosewood or ebony? Hell, ironwood, purpleheart, Padauk?
Hi! Enjoying the series. From an engineering standpoint, radiusing the top of the transverse brace would distribute load better then a flat surface. Or is the parabolic radiusing you mentioned? Ever think about an I beam or T beam cross section?
Let me start by saying I have not built a guitar yet (I'm watching this series as part of my due diligence before I even buy materials and tools). So this question is coming from someone who has zero hands on experience. If the purpose of the transverse brace is to add structural stability/strength to the soundboard beneath the neck, have you experimented with using materials besides wood? Perhaps the wood is simply strong enough and this would just complicate the building process unnecessarily, but I feel like reinforcing it with carbon fiber or even a light metal (e.g. aluminum) could add significant strength to it. I have no intuition for how this might affect the acoustics, but again, it seems like that shouldn't matter so much for the transverse brace. Interested to hear anyone's thoughts about this :)
Great theory and funny at the same time ,every time I get to that stage I pause thinking there is a better way. This will go into my next build,thanks !
Based on the rationale (which sounds right) Why not just use rosewood for the whole brace and leave it rectangular. By reducing the thickness in the centre you’re just recreating the same issue that was at the sides and putting it right where the neck is going to put all of the load.
Not really, the bending strength comes from the outer faces of a beam and penetrations usually get placed within the middle third. Just giving my knowledge as a structural engineer
The bending moments of the beam are so neutral in the center of the beam as to have no affect. That's why we're able to put lightening holes in wing spars and other aircraft structures with no penalty - on the contrary, we give up weight without giving up strength.
The Martin transverse piece does not touch the sides, to me that helps the sound sides vibrations, if your gluing it to the sides to me that helps ground out the sides from vibrating, however it will strengthen that area.....IMO
I laminate my sides in the belief that you don’t want the sides to vibrate at all. Doing so was the single largest advancement in my guitars tone. By containing the vibrations to the top and back, you get a WAY more responsive guitar. It has more punch, volume, and tone than with the sides taking energy away from the top and back. So yes, I think this technique is best. But I totally get why you’d do it another way. This is just what has worked best for me in experimenting with ways to make a better sounding guitar. Many hand builders are laminating their sides now as well.
i have a question in regard to the brace that goes behind the bridge of ab acoustic guitar and what it is called . because i have a guitar that was made without it and how can i fix that problem
In my opinion that’s snake oil. It doesn’t matter because every little bit of bracing to shape will change that note, and as soon as you glue it to the sides it’ll change again, then you apply finish and it changes again, then you glue on a bridge and it changes again. Lastly you add string tension and it changes again.
I've always heard that the areas above the transverse brace contribute to the treble end of the guitar. Do you have reason to believe it doesn't or is it just experience telling you that it doesn't make a significant difference?
It’s my experience really. Thanks believe you’re better off concentrating the vibrational area of the top to the area below the transverse brace. I have made many guitars in the past that I call my “Da Vinci” model, and it removed the sound hole and moves it to the side. Therefore making the soundboard twice as large, and it also eliminates the transverse brace in an attempt to use the entire soundboard from top to bottom. It made for more Bass response, but at as serious loss in volume and projection. Once I started laminating my sides, and making my transverse brace tie in better with the sides, it completely changed my tone for the better. This is all based on Ervin Simogi’s books on how to build a better guitar.
@@DriftwoodGuitars I've seen them on your website, I would love to try one. I've heard some amazing guitars that ditch the sound hole, I can't only imagine how your DaVincis must sound
would you put a transverse in a ukulele as well? since they usually only have nylon strings the load isnt as heavy. also have you tried stringing a ukulele with steel strings?
I do put transverse braces on my Ukes, but the lack of tension doesn’t really require this technique. I would only put Steele strings on one if it was braces to handle the tension.
If it's purely for strength. Then a laminated piece would be far superior to anything else you could use. Same with building. A laminated beam can be smaller, but is still far stronger than a piece of solid wood.
I totally agree. I did the color adjustments on a laptop with a lot of sunlight in the room, so I couldn’t really see the results very well. Are there websites I can download good LUTs packs from? I tried this by hand, and clearly missed the mark haha
@@DriftwoodGuitars then just a little color correction might do it. Since LUTs are usually used to get a certain look over the whole piece, it's not needed in every case. I use Davinci Resolve. It comes with several LUTs.
Not really. A well drilled hole shouldn’t affect strength. In fact the ribs and struts of an aircraft wing have holes in the to reduce weight, while maintaining the original strength.
I accidentally 1 - 5 whilst drinking beer. It's been a wild ride. A great insight into why they work like they do and how to make them better. I'm heading back to like the previous four burpy stomach grumbly episodes right now and waiting for the completion of the huge fart in the next video.
Well, with the brace against the sides (and the larger contact) the top will definitely be stiffer and stronger. I can't tell you he's right, but a stiffer brace is likely to stop more vibrations from propagating further up the top in a similar manner to how a finger restricts vibrations from propagating further along a string. The theory doesn't seem outrageous. I wonder how much is done because 'that's how it's done'.
PE Here. Spent 45 years doing exactly this. If the tie-in to the sides is complete, it will be very strong. The example Martin scallops the ends to 1)save weight, and 2) prevent a Stress Riser at the end. This forces the Stress to be distributed fairly equally all along the Transverse brace/top joint, with the neck loads going in to the top It does change the mode shapes (frequency response) of the top somewhat--I would expect these guitars to have a "Brighter" tone (Better high frequency response) than the Martin, with somewhat reduced low-end loudness--but not a hell of a lot.
Sorry, I’m a retired civil/ structural engineer and I disagree with the general premise. The biggest bending force (flexural stress) on a simply supported beam, is in the middle. The key here, is “simply supported,” with means it is allowed to rotate at the end supports. You can prove this for yourself, pretty easily, by cutting two short 2x4s to mimc the two different brace profiles, then supporting them at both ends on a block of wood or a saw horse. Push down in the middle and you will see what I mean. Now, by gluing the ends of the braces to the sides of the guitar, you no longer have a simple support; you have a “fixed support.” Without getting into all the Statics/Physics, you are basically transferring a tremendous twisting force (bending moment) into the sides of the body. If you don’t account for that, by increasing the side stiffeners at or near the ends of the trans brace, the sides of the guitar will eventually pull inward and crack. I know this is difficult t explain with words - and wish I could attach a couple sketches to this comment - but suffice it to say, it is complicated.
I think I understand what you’re saying, and it makes sense. With that said, you’ll see that I laminate my sides, and use solid merging, as I believe the sides should be extremely strong and not vibrate at all. The transverse brace is locked into my sides and it makes for an extremely strong joint.
@@DriftwoodGuitars makes sense. Why not keep the transverse brace the same thickness along it’s entire length? If it’s only purpose is structural (which I agree with), other than losings a few ounces of wood, there is no benefit from “scalloping” the middle of it. You’re building a 3000 year old guitar. I would just hate to see it experience a major failure because unforeseen internal stresses.
That’s a solid idea as well. I’m actually not making my middle area thinner than I did before I started this technique though. It’s the same height as when I scalloped the ends, I just make the ends twice as tall now to allow for more contact area with the sides. Maybe that’s a better explanation?
@@bldallas: By making the center portion, of standard thickness, shorter in length, he has made it stronger, without showing extra wood, through the sound hole. Think floor joists and span length.
This was a very interesting video and sparked some intriguing thoughts about the forces on a guitar. Been a guitar player for years and one day I hope to build one (or more). I also have a background in structural engineering and this foray into the transverse brace theory got me thinking "what, exactly, are the forces on an acoustic guitar and how, exactly, are they distributed in the instrument?" I watched the video on the Driftwood DaVinci guitar (with the 'floating' fretboard extension) and was wondering if you've measured the 'downward' deflection of the floating fretboard extension when the guitar is strung up to concert pitch. EDIT: here's an interesting video of a finite element analysis of an acoustic guitar. th-cam.com/video/otH6XGBu6Ig/w-d-xo.html
I think the engineering of your beam idea is flawed. Sure, it's tied to the sides well, but why not just make it the same thickness the full length, the added weight will be negligible. The anchor points adds no strength to supporting the fret board extension, the middle of the beam does. I too, put the TR access hole in the upper transverse brace, but I use a taller brace then you have here.
That is a "yes and no". His brace is, in the center, ~1/2" tall (vertical thickness) the standard size, for that brace. Being, the length, at that thickness has been shortened, it is now stronger. It's the same as building a house. The longer the span, of the floor joists, the taller (vertically thicker) they need to be. If a house, with a span of (just throwing out numbers) 30ft, requires joists 8" thick, a house with a span of 10ft may be able to use joists only 6" thick, for the same load. His brace is now stronger, without showing thicker wood, through the sound hole.
Hi Chris, really enjoy your videos. My thoughts as a structural engineer... it looks like what you are trying to achieve is getting the transverse brace to work as a fixed end beam rather than a simply supported beam (engineering jargon) which restricts rotation at the supporting ends rather than the ends just being pin supports. This will work provided that you get a solid glue join from the end grain (hard) of the braces to the sides, otherwise it doesn't add any bending strength and just adds weight to the brace. Think about how bridges are built where they are tallest in the centre and not so at the ends/supports, Sydney harbour bridge is a good example (note this is a completely different structural method than suspension bridges which do not relate to how a transverse brace works). It is far more effective to add depth to the centre of the brace and rely on the ends as simple supports which do not need to be thick as they act only in shear not bending. I'd be happy to elaborate further if you are interested. Kind regards, Dave
David, I agree,I was going to write a similar comment. Removing moment of inertia (area) by scalloping the center is directionally worse structurally.
@David Sutherland. Mahalo for those insights. What is the engineering term for a "beam" that is not supported at its ends and instead is just attached (glued) to a plate (soundboard). This is the opposite of what Driftwood Guitars does. Many guitar builders do not "tuck" their bracing into the sides/kerfing. It is my understanding that such an unsupported beam would not exhibit the same properties as a simply supported beam whereby the load is a function of the cube of the height of the beam.
I agree, I was thinking the same thing
Engineer here too. I immediately had the same thoughts. Structurally, the solution to scallop the brace in the middle does exactly the opposite that it is supposed to do. It reduces the moment of inertia of the brace in the section with the highest stresses and therefore weakens it. That’s the reason why you give your guitar tops and x-braces a radius, because it increases the moment of inertia in the middle of top and therefore makes it stiffer and capable to carry more load.
Glad to read this as I was thinking it as it was being mentioned in the video. I wonder if this design has been adjusted since.
Really look forward to watching these videos every week even though I have absolutely no business building guitars. You really make it accessible to a guitar player with zero background in lutherie. Just wanted to say thanks!
I appreciate you giving up your design secrets so the rest of us have the chance of being more successful. Mighty fine of ya!
My pleasure! I’m tired of all the secret squirrel stuff
I really like the fact that the inside look of your guitars is just about as important as the outside look. Amazing work. Thanks for sharing.
Thanks a lot!
I'm not a builder, just a guitar player, but this is fascinating to me. I just wanted to reach out and tell you how much I appreciate your knowledge and willingness to share what you have learned.
Maybe I will learn something that will make me a better guitar buyer. Lol
I can't wait to see how you tie that in with the sides. Makes total sense.
Whoever picks the background music is a stud. Love it!
Chris I did your mod to my bridge by cutting the slots in the Bridge. Sorry I'm responding in this video, but I'm here now. It WORKED! I believed your explanation, and I had to make my own saw because StewMac is out of the nice ones you recommended. I did my Epiphone Hummingbird which looks great and costs less than 400. It was a bit thick and dull before. It's braces I can see in the sound hole are huge and not scalloped . It was a nice looking but poor playing guitar. Now it sounds like a $600 guitar which is a huge improvement... Thanks from your new fan boy....
Damnit Chris… feed Matt. All camera, no food, makes Matt a noisy boy. Lol. Love the video guys.
You guys are upping your production with each of the videos. It's looking so good!
Thanks so much! We’re pretty proud of how far we’ve come in a short time. A lot of people complaining because it’s not perfect, but we’re trying our best.
@@DriftwoodGuitars I will never understand people who get on TH-cam and complain about someone else's work or art. They are not on TH-cam presenting their work
Hey guys, I second the props for your video quality upgrade. I love the nice close-ups, slow-mo, depth-of-field, and varied angles. Keep it up Matt!
In regard to the allen wrench hole in the cross brace and it's strength. Many years ago a friend was a forestry student at Oregon State Univ. They did stress testing on fir beams that showed that the greatest part of the stress was handled by the top and bottom surfaces of the beams. Putting holes in the middle did not affect the strength of the beams any significant amount. :)
Completely addicted to studying this build process…as in watched the first 4 episodes last night finishing around 1AM with a looming 5:30AM alarm for my workday. Great stuff and thanks for sharing so much of your process!
Oh no! Sorry we kept you up!
A number of classical guitar builders shape both (above and below the soundhole on a classical) transverse bars similarly, though more lightly. I hadn't reasoned why, but you make it clear. Thanks! Also, some classical builders use a slight arc but at the ends glue "pillars," which might have a similar reason. I have an early Martin D12-20 that was retrofitted with an adjustable truss rod. The transverse brace had been cut away almost entirely for access, leaving the unglued side open. I added a plug, a strap across the filled gap, laminated both sides of the brace, and redrilled the hole. It still needed a neck reset but not so badly. I hadn't thought about regularly sistering that brace, but it makes a great deal of sense. Thanks.
You gave me lots of food for thought. I never really put much thought into that part. I just copy what everybody else does. Can't wait to see how you bring it together with the sides. Good job with the videos.
Perfect timing for this video! I'm laying out the top bracing for my first acoustic build and will be using your ideas.
Having said that, if it is tied really firmly to the sides, it would acutally need to pull the sides in in order to deflect...hmmm. And just seen that the addition of the rosewood makes it the same as a composite beam and will strengthen the brace. Nice...not just decorative.
Correct. I didn’t do Avery good job of explaining it appears!
Love the coffee mug at the end ;)
I see a lot of the comments worried about the hole in the brace. If I am not mistaken the top will also be glued to the neck extension and fretboard right over this hole. That is usually 2 different woods (3 if there is binding) added to the top and the brace and the side laminate on the brace for a total of 5 to 7 different pieces of wood in 5 different orientations around that hole. Probably pretty strong.
Hi Chris, your analogy about the roof beam isn't correct from a structural integrity viewpoint. The ends of a beam only need to resist shear forces, whilst it is the middle of any beam that rely on sufficient depth to resist deflection. It is the centre of the beam that has the most work to do. (You may wish to read Structures : Or Why Things Don't Fall Down by J.E. Gordon). I'm extremely curious about your conclusion and how this may effect the longevity of this amazing guitar build. Loving your vids BTW.
Nice camera work, thanks! You thoughts about the transverse brace are really interesting. My first reaction was negative, but it does makes sense. And, I radiused my transverse brace. Grrr. I see a number of ways forward. On I go!
Great quality video. And yeah why do we scallop the transverse bar. Lol. I think I would leave a hump above the truss hole to retain some strength, but maybe the rosewood is enough.
New rig looks sweet! The slowmo is a nice add as well. As an architect, I can see why you would scallop the transverse brace as the bending stress would be greatest at the center. However, the sheer stress would be greatest at the ends. With scalloped ends, the top would be able to allow flexture at the edges and would therefore it would allow a wave across that section of the guitar over time. If your plan is to lock the top down at that point, the tall edges would def be a better move... My question is whether the radius on the body sides above that brace creates an odd geometry that is flat across the brace and radiused around edges... I suspect its marginal.
Your work is an incredible source of joy...don't stop!
I appreciate that!
Awesome! Finally got to be the 1000th person to like one of your vids. Just starting out on my luthier journey and your channel is gold. When can I come for an apprenticeship? I kid. Keep em coming!
Very enjoyable, always nice to watch someone who knows what they are doing! Thanks for sharing! KANSAS
Learning so much! And.. having fun watching your videos.
Enjoying this series quite a bit, the transverse brace arguments aren't clicking though. I'll wait until things come together, see if it makes more sense or I can ask some reasonably informed questions.
How to Build an Acoustic Guitar. Episode 5
Hi Chris, thanks for the video. Please kindly clarify the topic in regards to avoiding stress in the top-plate. At 7:50 (on the runtime) you show how once the 35° braces have been glued in-place, it forces a 35° radius on the top-plate as shown at 7:50 when you rock the top back and forth.
In a perfect world, (aside from the braces being sanded to conform to a 35° radius) wouldn't the top-plate also have to be radiused to 35° as well before gluing on the braces? I understand this would be a daunting task.
The way you explained earlier is that you don't want any stresses in the top because it can inhibite the vibrations. If the top-plate is 'essentially' being "forced" (stressed) into a 35° radius as a result of gluing down the braces, isn't that introducing stress into the top? My understanding is that the top-plate will always want to return to a flat position (0° radius) causing stress. I do hope I explained this clearly. Thank you Chris.
Some food for thought for those commenting about the transverse brace, part of the somogyi style (the book mentioned) is to also butt a 'fretboard' extension into the transverse brace. Basically distributing the load of the neck block intro the transverse brace that is buttressed against the sides/kerfed linings..Also great video, and content
I do that at a later point in the build. I forgot to mention it in the video
@@DriftwoodGuitars Nice, Don't know why people are getting so worked up over it!
That’s guitar enthusiast for ya haha
The brace will only be as strong as it's smallest cross-section therefore the truss rod hole will weaken it where it's drilled (this might be why others shape it wider at this point and down at the edges). The lower portion of the brace below the truss rod hole will be in tension when the neck is under load. An unshaped brace would be stronger. It should be pretty easy to model the stresses using CAD to see the differences in the designs.
Not correct, the ends work in shear which do not need to be as big, the centre works in bending where the depth and the outer faces has greater effect than overall cross section and centre penetrations are permissible. This is routinely utilised in many engineering applications
@@davidsutherland1825 That was kind of my point, slimming the brace down in the middle and then drilling a hole is, in my mind, going to create a weaker brace not stronger that a traditional one. An unshaped one will be stronger (even if the strength is not needed). I might model it up in CAD and do some stress analysis.
Doesn't that hole for the truss rod access compromise the structural integrity of the transverse brace now that its that short in the middle? With the string tension pulling the neck, there is a significant amount of pressure from the neck onto that part of the top, that it my thought about it. Looking forward for your explanation.
That’s some sweet B-roll 🎥
Nice video and the new camera is awesome. The colors were very cool - almost green - though
I'm a want to be guitar builder and I watch you and the big guy from Canada....I love your projects would love to try one of your guitars
I'm not a builder (yet). I jam with a builder who made my OM-28k to pre-war spec (he's a devout traditionalist). This instrument can stand right up to his well-maintained prewar Martin collection...
However.... he has inspired me to build. I've been acquiring tools.
The engineer in me disagrees with your transverse brace design. In industry, I've seen welded support beams made like the traditional transverse, tapered at the ends. The buildings are still standing.
Given that the brace is glued to the top (which now becomes a structural co-brace), tapered ends just make more sense to me.
But hey, if your design works... go for it. The beauty of all the builders out there is innovation (my friend not included, he wouldn't dare waver from tradition)... I would...
I've made electric guitars... but what is a solid body guitar but a plank, with a nice neck.
Looks much better overall vs the old rig. Slow motion and panning shots look so professional! Perhaps there could be less grey/green in the colour grade and something could be done to the autofocus when you do the headshots - it's rather jumpy and noticeable in the background. Great work! And thank you so much for the incredibly useful and educational content!
Yeah I’m still trying to fissure out how to color grade correctly, and missed the mark on this one haha. We’ll get it all sorted in time!
@@DriftwoodGuitars I think you guys did great! Love your work!!!
Coming from a photographer, I appreciate that
@@DriftwoodGuitars I think you are too modest, sir! I know your dad is a photographer and filmmaker so I am sure you are as least as good as me)
Thanks guys. I would think that if you're looking for the strongest, lightest beam, the trusty old I beam would do the trick. Maybe laminated with multiple pieces of wood.
What? Now you are Video Producers? Looks good great info and insight.
With all the extra efficiency you have put into your building, I am surprised you haven't put a taper on the hole to make it easier to find while having the taper guide the wrench to the right location.
That’s a solid idea actually!
@@DriftwoodGuitars I'm glad you liked it, just thinking along the process :-)
Loving the content man! You should do a vid showing your spray booth setup/ guns/ techniques. Would def be interested. I just started using nitro about a week ago.I used water based before, due to lack of a proper booth. Now I finally gave the proper facilities for nitro. Man it's so much better than water based! Never going back haha
We now sell hand selected and resawn Tonewoods on our website! Each piece was found by Chris Alvarado, and almost always has a story to go along with it. Go check out the selection at www.driftwoodguitars.com/tonewood
Just look at the shape of a bridge. The road support is thicker on the outside and thinner in the center.
Loving this series! Very thought provoking video, “Why is it shaped like that?” This is why I love lutherie because of the multiple variables in play at the same time and having to account for them.
Correct me if I’m wrong, but your braces (measured in the center) seem to be very similarly sized to the Martin in the video. Is the ½ inch height at the center of the brace about “standard”? If so, your brace is effectively the same strength as a “traditionally shaped” transverse brace with the additional surface area in the ends.
This begs the question, if this brace is purely structural as mentioned, why do we bother to “shape” this brace at all? Borrowing from the A-frame roof analogy, those beams are not shaped and are just full sized rectangles. Is it because every other brace is “shaped” that this brace also has to be “shaped”? If maximum strength is our goal and weight is not a consideration, because this bar is the effective boundary of the moving top, then why not just leave this brace unshaped? If we want our sides to be as stiff as possible (laminated sides) and use solid linings for their stiffness. It would seem that a stiff perimeter is the goal. If the transverse brace is effectively part of the “perimeter” of the soundboard then why not make it as stiff as possible = no shaping/reduction of material? Why is this brace shaped at all? lol. Or is an unshaped brace synonymous with “cheap” construction?
If your brace height at the center is the same as a “normal” transverse brace it seems like you have a solution which fulfills both the form (shaping for aesthetics) and function (strength) of a "traditional" transverse brace with the minimal drawback of adding minimal weight to the "perimeter".
As I was following your thought process on making that transverse much stronger, it seemed odd to then drill a hole in the middle of the beam which would weaken it? Is it not the middle that needs to be the strongest part but rather more so your explanation of just tying it to the sides that is more important? Love following the build and aspire to build an acoustic someday!
I believe that the extra material to tie it into the sides is the most important factor here.
If you think about a road bridge, it doesn't really matter : the "arch" is making it strong, not the amount of material. Well, on the principle at least ! One suggestion though : what about linking your transverse brace to the side braces ? then you would have a complete Eiffel road bridge !!!
@@jean-yvescabon2892 but the transverse brace isn’t an arch, it’s a beam. And as such, it will be the flexiest where it’s the thinnest. Many steel beam bridges are shaped in a similar fashion to the traditional transverse brace.
@@migrantfamily Keep in mind the brace is glued to the top all along it's length. Steel beams usually just have support at the ends.
A hole in the center is not an issue. Strength comes from depth of section, not the amount of material. As long as the hole is not in the outer 1/3 s and is centered top-to-bottom (on tje neutral axis or very nearly so) its not an issue
I WOULD LOVE TO LEARN FROM YOU HOW TO DO THIS
Hi, physicist here)
Main problem with fretboard over soundboard is soundboard's bending, not moving whole soundboard to backside. Thus, in this place height of the transverse bar is much more important then how one glues to the sides. To be more precise, height and length of those height - to have substantial brace outreach from each side of the fretboard.
Nevertheless, this profile provides incredibly rigid structure in those area the affects sound for sure. I think it (could be) good for steel-string guitar, but its too rigid for nylon-string guitar...
Also, you could look for train-bridges frames - almost always they have narrow ends and tall middle part. Exactly because those bending supremacy over other movements.
Congrats!
yay 1st' also you should write a book on how to build guitars, cheers from Sydney Australia!
You should etch your company name on the rosewood that you put on the transverse at the truss rod hole
That’s a solid idea right there
@@DriftwoodGuitars you're welcome! I am not a builder. Just a player but I have been playing for about 60 years and made a point of understanding build methods so I can know what I'm buying and what to look for. Your are an impressive builder and you remind me of David Furch of Furch guitars in the way you approach tone and strength in your guitars.
Thanks for sharing.... I apreciate that 👍
Based on your explanation of the purpose of the transverse brace, I don''t understand why you carve out the center. Why not leave it at maximum thickness all the way across in order to increase its strength in the center? This would also make the upper part of the top less resonant, I would think.
I think both things , carbon fiber, and dog bone joint make sense and I think you are on to something. Check out against the grain instruments here on youtube he has a unique neck joint also and a sort of acoustic /electric hybrid. I tried to post this on your video of Rhett Shull's guitar but it wouldn't let me
Interesting. First make your brace stronger than drill a large hole through the center and make it substantially weaker. Question: Have you tested your brace's strength? First as a solid brace, then with the hole and no lamination, next with hole and laminated support (one side only) and finally with the hole and two sides laminated? The test results would be very informative and enlightening.
The ribs on an aircraft wing as well as many of the support beams on a bridge have holes in them for weight reduction. A properly drilled hole, should insignificantly reduce strength. I hate Trussrod covers, and the hole is required to access it from the sound hole. The main strength added comes from the extra material on the sides that can now be glued to, and jointed with the sides.
My Laravee got around this by not allowing access through the transverse brace or through the headstock, there's a special, big, curved Allen wrench that they give you with the guitar to reach it, it's a real pain in the ass. I had to get a mirror down in there to finally get it in properly
@@DriftwoodGuitars Aluminum wing frame not a good analogy due to the number of trusses (struts) and material used. Holes in wood are another story altogether. See: building codes re house beams (floor-ceiling joist) and holes cut through. You did not answer my question re testing of your truss in different forms. Just seems counterintuitive to design a thicker brace then defeat the purpose by drilling a large hole through it. (See Gabriel's comment below)
@@0whitestone So you recognize the issue of drilling large holes in small wood braces! Adding the lamination helps but is it sufficient to offset that huge hole in the center? That was my question. I suspect the brace's proximity to the headstock likely offsets flex issues there above the sound hole. Maybe a moot issue?
@@patrickleary2389 My point was actually how inconvenient it is to not have the hole. Every other guitar I own that has access through the sound hole has a hole in the transverse brace, this includes Martin's and 40-year-old Takamine. I don't think it's going to cause any issues because it hasn't on any of my other instruments. I'm going to trust Chris on this, besides, if there's any issues with a guitar you purchase from him, I'm sure he'll honor his workmanship on it.
Why not make it 14-15mm all the way across? Maybe taper it or make it parabolic on the frontside and flat so the neck support can butt up against it. Wouldn't that make that whole area more stable? I see most acoustics have a gap in that area. I build Bajoquintos and always butt the neck extensión to the upper transverse brace. Never understood why they dont do that with acoustics. Those templates are DOPE by the way. Do you have a vid on how you make them?
Interesting transverse bracing. Wondering if drilling the truce rod hole, which looks like it removes about 70% of the material in the middle of that brace, is countering what you’re trying to do here. The rosewood piece adds some strength back, but just wondering..
Oops. Truss rod….
The book you reference, is it Ervin Somogyi's book? I'm reading that one right now.
Yes it is
Transverse brace. I wonder have you ever tried to narrow it down at the top and then it Like a Knife Edge and maybe lose a little weight? Just curious
Another thing you never see in house construction are beams with holes in the middle. If you really want the transverse brace to strong you need headstock truss rod adjustment. But I don’t like that either.
The ribs on an aircraft wing as well as many of the support beams on a bridge have holes in them for weight reduction. A properly drilled hole, should insignificantly reduce strength. I hate Trussrod covers, and the hole is required to access it from the sound hole. The main strength added comes from the extra material on the sides that can now be glued to, and jointed with the sides.
@Dane Nichols:
Yes, you do. Go into the basement of a residential construction.
You will see this principle being applied:
"Code says that you may not staple wires to the bottom of a floor joist unless the wire is 6-2, 8-3, or larger. Smaller wires must be run through bored holes or be attached to a running board.:
Plumbing is, also, run through floor joists. Notching is bad, centered drilling is OK.
@@zapa1pnt we were talking about a structural beam not floor joists. You can't drill any size hole through a structural beam. Agreed notching is bad, that is in essence what Chris is avoiding by making the brace thicker at the ends.
@@DriftwoodGuitars, Engineered trusses are made to have space. You have made a truss of sorts by adding the rosewood but the is it would be stronger with no hole at all. Which I agree is hard to do if you don't want to weaken the headstock with truss rod access. Maybe a bridge truss style traverse brace would check all the boxes.
Hi, I'm a structural engineer, penetrations through the centre third of a beam centre are commonplace as the bending strength comes mainly from the outer (top and bottom) faces. Consider an I-beam which has large top and bottom plates with a tiny web in the middle
🤣🤣🤣 LOVE the coffee cup! 🤣🤣🤣
Always great to watch your content
That music 0:20 to 0:42 🤩
Can someone specify its source ?
I’d love to read symogi’s book but at around £200 I’ll have to just go with your expert advice :).
great video! just a tip, I think you might want to take some time getting your white balance right for the shop on the new camera-it looks like a lot of the blues have been washed out a bit
100%! The struggle is real haha
Looks more like they posted it in S-Log without doing color timing.
@@DriftwoodGuitars no worries haha it’s a process
Hello Chris. Awesome videos!! I'm not a guitar builder but I'm absolutely fascinated. I have a question. I would like to buy a new Bourgeois Soloist. Madagascar back and sides and Sunburst Carpathian spruce top. I can get it for 7K. Any thoughts?
I know this is an older video, but how would you go about making a transvers bar for a guitar with a corner soundhole? Something along the lines of your DaVinci models.
Chris, it takes you 250 - 300 hours to build perfect guitar. What would be minimum in terms of hours for you to build good basic acoustic with no beautiful, but time consuming details ( inlays, binding, purfling, bevels )? Would such approach generate much lower price for still high quality instrument? I have seen video about US guitar maker, stated that they produce one acoustic weekly per luthier.
I wonder if you would answer a question for me, I have some purple heart, some island mahogany, and some black walnut, which would be best for the bridge of an acoustic?
I like the concept in your version of the upper transverse brace. Having been in Construction for the last 40 years it makes complete sense. However there is one aspect that bugs me about it. Your trussrod hole seems large in diameter through what has become the thinnest section of the transverse brace. From a constructional point of view this would be considered a no no. Would it not be better to make say the very centre section of the brace thicker over the centre section to improve structural strength over the area thats been weakened by drilling a hole through it, in a not too disimilar way to the ends of the brace?. The tiny additional weight of this slight thickening would most probably have no effect on tone as the idea is to get the bit of soundboard below this brace to vibrate freely not above it?. Just thoughts...
I believe you’re right!
@ Alex Ryder:
Martin guitars use the same 1/2" thick transverse, with a hole in it for truss rod access.
By making the 1/2" span shorter, he has made it stronger.
I don't get it - if the transverse bar is not about sound/vibration, and instead about strength and support, what are you still using Spruce? Why not make it rosewood or ebony? Hell, ironwood, purpleheart, Padauk?
Hi! Enjoying the series. From an engineering standpoint, radiusing the top of the transverse brace would distribute load better then a flat surface. Or is the parabolic radiusing you mentioned? Ever think about an I beam or T beam cross section?
It would make it strong, but would cause issues with the neck joint and playability on the high frets.
Muito top o conteúdo
Let me start by saying I have not built a guitar yet (I'm watching this series as part of my due diligence before I even buy materials and tools). So this question is coming from someone who has zero hands on experience.
If the purpose of the transverse brace is to add structural stability/strength to the soundboard beneath the neck, have you experimented with using materials besides wood? Perhaps the wood is simply strong enough and this would just complicate the building process unnecessarily, but I feel like reinforcing it with carbon fiber or even a light metal (e.g. aluminum) could add significant strength to it. I have no intuition for how this might affect the acoustics, but again, it seems like that shouldn't matter so much for the transverse brace.
Interested to hear anyone's thoughts about this :)
Great theory and funny at the same time ,every time I get to that stage I pause thinking there is a better way. This will go into my next build,thanks !
Is there any sense in making the transverse brace an I-beam? Would the ends need to be glued to the sides?
Great chicken foot mug!
Based on the rationale (which sounds right) Why not just use rosewood for the whole brace and leave it rectangular. By reducing the thickness in the centre you’re just recreating the same issue that was at the sides and putting it right where the neck is going to put all of the load.
I don’t reduce the thickness in the center at all, I keep it at its full height, and just make it even taller on the ends.
Doesn’t that truss rod access hole weaken the transverse brace?
Not really, the bending strength comes from the outer faces of a beam and penetrations usually get placed within the middle third. Just giving my knowledge as a structural engineer
I'm curious how the strength/stiffness of the brace changes after putting s such a relatively large hole through the middle.
The bending moments of the beam are so neutral in the center of the beam as to have no affect. That's why we're able to put lightening holes in wing spars and other aircraft structures with no penalty - on the contrary, we give up weight without giving up strength.
The Martin transverse piece does not touch the sides, to me that helps the sound sides vibrations, if your gluing it to the sides to me that helps ground out the sides from vibrating, however it will strengthen that area.....IMO
I laminate my sides in the belief that you don’t want the sides to vibrate at all. Doing so was the single largest advancement in my guitars tone. By containing the vibrations to the top and back, you get a WAY more responsive guitar. It has more punch, volume, and tone than with the sides taking energy away from the top and back. So yes, I think this technique is best. But I totally get why you’d do it another way. This is just what has worked best for me in experimenting with ways to make a better sounding guitar. Many hand builders are laminating their sides now as well.
Lighting is a little off compared to GoPro. Seems less bright. Camera adjustment?
Yeah I messed up the color grading, I’ll do better on the next one!
i have a question in regard to the brace that goes behind the bridge of ab acoustic guitar and what it is called . because i have a guitar that was made without it and how can i fix that problem
I can see the logic of the transverse brace
What? No transverse brace rosewood piece acrylic gluing template? JK.I do love your templates.
That’s a good idea!
What is the book you mention?
At which note the guitar top should be tap tunned...I saw some people doing this stuff by using tunner...but don't know at which note..
In my opinion that’s snake oil. It doesn’t matter because every little bit of bracing to shape will change that note, and as soon as you glue it to the sides it’ll change again, then you apply finish and it changes again, then you glue on a bridge and it changes again. Lastly you add string tension and it changes again.
@@DriftwoodGuitars thank you sir..👍
I've always heard that the areas above the transverse brace contribute to the treble end of the guitar. Do you have reason to believe it doesn't or is it just experience telling you that it doesn't make a significant difference?
It’s my experience really. Thanks believe you’re better off concentrating the vibrational area of the top to the area below the transverse brace. I have made many guitars in the past that I call my “Da Vinci” model, and it removed the sound hole and moves it to the side. Therefore making the soundboard twice as large, and it also eliminates the transverse brace in an attempt to use the entire soundboard from top to bottom. It made for more Bass response, but at as serious loss in volume and projection. Once I started laminating my sides, and making my transverse brace tie in better with the sides, it completely changed my tone for the better. This is all based on Ervin Simogi’s books on how to build a better guitar.
@@DriftwoodGuitars I've seen them on your website, I would love to try one. I've heard some amazing guitars that ditch the sound hole, I can't only imagine how your DaVincis must sound
I have a bunch of 20 year old IPE flooring 5 inches wide solid wood. Is it worth anything. Most of the boards are 4 to 5 ft long.
It’s certainly worth something! It’s not very useful for acoustic guitars but it’s very valuable as an exterior wood for furniture or decking.
would you put a transverse in a ukulele as well? since they usually only have nylon strings the load isnt as heavy. also have you tried stringing a ukulele with steel strings?
I do put transverse braces on my Ukes, but the lack of tension doesn’t really require this technique. I would only put Steele strings on one if it was braces to handle the tension.
I don't think steel strings, on a ukulele, is a good idea.
The extra bracing needed, on such a small structure, would
deaden the resonance terribly.
Is that the new camera?
Looks sharper than ever
But the colors does not look right, a bit washed or something
Yeah I’m still trying to sort out the color grading haha. Missed the mark on this one.
Just curious. How do you deal with squeeze out under the template?
It’s reduced by not applying too much glue, but then I just remove it once it’s dry with a chisel.
@@DriftwoodGuitars
I think he means, how do you manage to get the template off, without damage?
@@zapa1pnt wood glue won’t cure to whatever material he made it from. Intelligent design.
If it's purely for strength. Then a laminated piece would be far superior to anything else you could use. Same with building. A laminated beam can be smaller, but is still far stronger than a piece of solid wood.
he color has changed what , whit the new camera , more Yellow-ish , but nice , can’t wait to see the next video
Yeah the old camera didn’t have a natural look to the colors.
Plus we’re still learning how to color grade the new videos to look natural. In time!
Good luck too you , iff it gets as good as the guitarbuilding , there will be no problem .
Maybe you should look into some LUTs, because your skin actually looks green with the new camera IMHO.
I totally agree. I did the color adjustments on a laptop with a lot of sunlight in the room, so I couldn’t really see the results very well. Are there websites I can download good LUTs packs from? I tried this by hand, and clearly missed the mark haha
@@DriftwoodGuitars
Here's a start:
www.rocketstock.com/free-after-effects-templates/35-free-luts-for-color-grading-videos/
@@DriftwoodGuitars then just a little color correction might do it. Since LUTs are usually used to get a certain look over the whole piece, it's not needed in every case.
I use Davinci Resolve. It comes with several LUTs.
Ok I get the purpose of the transverse brace.....but then you drill a rather large hole in it, thus, vastly reducing the load carrying ability.
Not really. A well drilled hole shouldn’t affect strength. In fact the ribs and struts of an aircraft wing have holes in the to reduce weight, while maintaining the original strength.
Actually, it just needs to be perfectly centered, vertically.
I accidentally 1 - 5 whilst drinking beer. It's been a wild ride. A great insight into why they work like they do and how to make them better. I'm heading back to like the previous four burpy stomach grumbly episodes right now and waiting for the completion of the huge fart in the next video.
Hahahaha stay tuned.
Hi, has that theory actually been tested from an engineering perspective?
Well, with the brace against the sides (and the larger contact) the top will definitely be stiffer and stronger. I can't tell you he's right, but a stiffer brace is likely to stop more vibrations from propagating further up the top in a similar manner to how a finger restricts vibrations from propagating further along a string. The theory doesn't seem outrageous. I wonder how much is done because 'that's how it's done'.
It's, pretty, simple. Just think floor joists and span length.
PE Here. Spent 45 years doing exactly this. If the tie-in to the sides is complete, it will be very strong.
The example Martin scallops the ends to 1)save weight, and 2) prevent a Stress Riser at the end. This forces the Stress to be distributed fairly equally all along the Transverse brace/top joint, with the neck loads going in to the top
It does change the mode shapes (frequency response) of the top somewhat--I would expect these guitars to have a "Brighter" tone (Better high frequency response) than the Martin, with somewhat reduced low-end loudness--but not a hell of a lot.
Smooth movement but the colors are bit of and dull with the new camera
Yeah I’m still learning how to color grade correctly, bare with us. Can’t master videography in one month.
Transverse brace theory into glue porn... unexpected but well played. I'm spent.
Sorry, I’m a retired civil/ structural engineer and I disagree with the general premise. The biggest bending force (flexural stress) on a simply supported beam, is in the middle. The key here, is “simply supported,” with means it is allowed to rotate at the end supports.
You can prove this for yourself, pretty easily, by cutting two short 2x4s to mimc the two different brace profiles, then supporting them at both ends on a block of wood or a saw horse. Push down in the middle and you will see what I mean.
Now, by gluing the ends of the braces to the sides of the guitar, you no longer have a simple support; you have a “fixed support.” Without getting into all the Statics/Physics, you are basically transferring a tremendous twisting force (bending moment) into the sides of the body. If you don’t account for that, by increasing the side stiffeners at or near the ends of the trans brace, the sides of the guitar will eventually pull inward and crack.
I know this is difficult t explain with words - and wish I could attach a couple sketches to this comment - but suffice it to say, it is complicated.
I think I understand what you’re saying, and it makes sense. With that said, you’ll see that I laminate my sides, and use solid merging, as I believe the sides should be extremely strong and not vibrate at all. The transverse brace is locked into my sides and it makes for an extremely strong joint.
@@DriftwoodGuitars makes sense. Why not keep the transverse brace the same thickness along it’s entire length? If it’s only purpose is structural (which I agree with), other than losings a few ounces of wood, there is no benefit from “scalloping” the middle of it.
You’re building a 3000 year old guitar. I would just hate to see it experience a major failure because unforeseen internal stresses.
That’s a solid idea as well. I’m actually not making my middle area thinner than I did before I started this technique though. It’s the same height as when I scalloped the ends, I just make the ends twice as tall now to allow for more contact area with the sides. Maybe that’s a better explanation?
@@DriftwoodGuitars ahhh. Good call! Thanks for your replies; I really enjoy your videos.
@@bldallas:
By making the center portion, of standard
thickness, shorter in length, he has made it
stronger, without showing extra wood, through
the sound hole.
Think floor joists and span length.
This was a very interesting video and sparked some intriguing thoughts about the forces on a guitar. Been a guitar player for years and one day I hope to build one (or more). I also have a background in structural engineering and this foray into the transverse brace theory got me thinking "what, exactly, are the forces on an acoustic guitar and how, exactly, are they distributed in the instrument?" I watched the video on the Driftwood DaVinci guitar (with the 'floating' fretboard extension) and was wondering if you've measured the 'downward' deflection of the floating fretboard extension when the guitar is strung up to concert pitch.
EDIT: here's an interesting video of a finite element analysis of an acoustic guitar. th-cam.com/video/otH6XGBu6Ig/w-d-xo.html
I think the engineering of your beam idea is flawed. Sure, it's tied to the sides well, but why not just make it the same thickness the full length, the added weight will be negligible. The anchor points adds no strength to supporting the fret board extension, the middle of the beam does. I too, put the TR access hole in the upper transverse brace, but I use a taller brace then you have here.
A valid argument for sure. I think everyone will have a better understanding of my reason for doing this once we get further into the build.
That is a "yes and no".
His brace is, in the center, ~1/2" tall (vertical thickness) the standard size, for that brace.
Being, the length, at that thickness has been shortened, it is now stronger.
It's the same as building a house. The longer the span, of the floor joists, the taller (vertically thicker)
they need to be. If a house, with a span of (just throwing out numbers) 30ft, requires joists 8" thick,
a house with a span of 10ft may be able to use joists only 6" thick, for the same load.
His brace is now stronger, without showing thicker wood, through the sound hole.
There it is! You said it batter than I could. Maybe I’ll design some experiments and do a video on it.