Official Luthiers Forum!

Just wanted to post a quick note to say hello. I have been checking out the OLF for a while, and note a bunch of superb luthiers hanging out here, sharing ideas.

I'm no luthier (yet) but I have a history of fine woodworking, architectural millwork, and had a tiny company (years ago) specializing in tropical lumber that was certified as Rainforest Alliance Smartwood. I just mention those things to say that I'm not a stranger to wood or woodworking, but I don't have any real luthier experience yet.

I started an acoustic steel string about 25 years ago, and never finished it. (Bent a set of sides with an S cutaway, started a neck, etc.) I have started fresh, and I am going to get one done this time! I have collected a few tools, drawn (on CAD) a set of plans, and have made male and female molds. I have some wood, parts for a heat blanket bending system, radius dishes, lots of clamps, and spray equipment.

Well anyhow, nice to be here. I'll try to be quiet and sit in the corner, watching and listening.

Dennis

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Dennis Leahy
Duluth, MN, USA
7th Sense Multimedia

Ahh yes another one crazy enough to jump into the world of guitar building.

Welcome aboard!

Josh

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Josh House

Canadian Luthier Supply
http://www.canadianluthiersupply.com
https://www.facebook.com/canadianluthiersupply?ref=hl
House Guitars - Custom Built Acoustic Instruments.
http://www.houseguitars.com

hi dennis

glad you've decided to join us.

Hey Dennis, welcome.

We can always use another person with lots of woodworking/wood experience and knowledge. Let's see those plans you drew up!

Jeff

Welcome to the OLF, Dennis. Whatever you do, don't sit quiet. I'd like to hear more about the Smartwood.

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Don Atwood
Arlington, VA

[QUOTE=Jeff Doty] Hey Dennis, welcome.
Let's see those plans you drew up!
Jeff[/QUOTE]

OK, I've been here an hour, and already someone at the poker table said "I call." Dang, I thought I could hang in the corner for a while before unveiling my insanity...

Well, I have been thinking about this for a looooong time (maybe too long.) One thing that stuck in my head was that the X-brace that was the brilliant brainchild of Martin might also be somewhat limiting, when it comes to allowing the top to produce sound. The "problem", as I see it, is that the X-brace is trying to perform two tasks simultaneously: keep the top from deforming due to string tension, and act as tone bars. So, I wondered what would happen if I included two sets of braces, each one optimized to do one task. One set of braces that are structural, and another set of braces that promote tone and allow the maximum amount of string vibration to affect the top. I knew I couldn't just drop the X-brace down into the body cavity and away from restricting the top movement, (sort of a "flying X"), because the strings anchored at the bridge still require bracing to resist both the shear and torque forces. So, I knew I needed to work with a tailpiece to reduce the shear and torque on the top.

As a matter of personal preference, I prefer the sound of a "flattop" acoustic to an archtop. I am convinced that the typical moveable bridge, with the typical relatively shallow break angle, cannot deliver the "punch" that I enjoy in flattop instruments. So, I came up with the idea of making a bridge that incorporates some features of both. The bridge is basically a pinless bridge (which has a 15° break angle over the saddle), but rather than stop the ball ends at the bridge, I decided to drill tunnels and allow the strings to pass through the bridge. The strings then connect at the tail. I decided to play with form and function at the tail, and use a "tail-less tail." Commercially available string length and an appreciation of the female form molded the overall shape, including the tail.

With no shear force on the bridge (but still having a torque force), I was now able to rethink the bracing. I sketched a set of structural braces to deal with the force of the string pull from the tail. These structural braces float or fly beneath the top, making very slight contact with the soundboard only at their ends.

That left the tone ("sonic") braces. After several earlier sketches creating a piston-like set of sonic braces, I read Siminoff's book. I became convinced that the bridge, though unorthodox, will still act a lot more like a pin/pinless bridge than a moveable bridge. In other words, it will rock more than pump. So, I started over on the sonic bracing, and drew a set of radial braces with a single fulcrum-like brace beneath the bridge. The bridge and braces are rotated to fall in line with the compensated saddle line.

So, there's my train of thought, and here's my drawing:



In the top section/sketch, the structural braces are shown in red, and the sonic braces are shown in blue.

Dennis

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Dennis Leahy
Duluth, MN, USA
7th Sense Multimedia

Well Dennis I see everybody is speechless. I'd love to hear it one of these days. you've jumped right in the deep end. Go for it.

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Tickle your guitar daily, and it'll tickle you back.

I see that you've changed almost everything about the bracing on the guitar. If it sounds great, then you're OK. If, however, there are problems with the sound, then which particular design element is the problem. It is going to be very difficult to analyze and make corrections.

I can't tell from the drawing but are your structural braces in full contact with the soundboard or are they "flying" and only connected at the ends? If they ary in full contact, how are you dealing with the intersections of with the tone bars?

I like the looks of the guitar. It has a nice modern feel.

With your bridge design, there really is no structural reason to run the strings all the way to the tail. There might be a sonic effect with the strings behind the bridge resonating.

welcome onboard Dennis. I will be nice to have you with us

[Quote][Josh H
Ahh yes another one crazy enough to jump into the world of guitar building.
Welcome aboard!
Josh[/QUOTE]

Hi Josh,
I'm passionate, but not crazy enough to think I will ever sell one. I could never afford a harem of guitars, (and maybe an acoustic bass or two), so my only chance is to build them.

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[Quote]crazymanmichael
hi dennis
glad you've decided to join us. [/QUOTE]

Thanks Michael,
Seeing you here was one of the things that convinced me to join. I'm actually not convinced that you're crazy!

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[Quote]Jeff Doty
Hey Dennis, welcome.
We can always use another person with lots of woodworking/wood experience and knowledge. Let's see those plans you drew up!
Jeff[/QUOTE]

Hi Jeff,
If I chime in with much of anything, it might be to answer newbie questions about grain orientation or something like that. I'm also likely to offer applause when I see the quality of work that I have been viewing here.

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[Quote]Don A
Welcome to the OLF, Dennis. Whatever you do, don't sit quiet. I'd like to hear more about the Smartwood.[/QUOTE]

Thanks, Don
I'll offer some info in a post about Smartwood at some point, including my observations of a few lesser-known species that I believe are superb candidates for tonewoods. I don't have the money to pursue starting back up with an exotic lumber business, but if I did, I would find out who in the world is currently producing Smartwood, or FSC certified wood.

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[Quote]John How
Well Dennis I see everybody is speechless. I'd love to hear it one of these days. you've jumped right in the deep end. Go for it.[/QUOTE]

Hi John,
The deep end indeed, and wearing a weight belt! Honestly, this is an itch I just have to scratch. If it proves to be folly, I will probably try copying a well known instrument. When it's done, I will give my honest assessment of the sound. If it is at least "good", I will pass it around to a few musicians to get more feedback. I'll even try to record an MP3 or a WAV file of the sound, and post a link to it (if anyone is interested.)

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[Quote]Mike Mahar
I see that you've changed almost everything about the bracing on the guitar. If it sounds great, then you're OK. If, however, there are problems with the sound, then which particular design element is the problem. It is going to be very difficult to analyze and make corrections.[/QUOTE]

Point well taken. Everything is conjecture at this point. I will not have the experienced help of hundreds of willing luthiers if I say "the treble is missing" or "the mids are muddy." Those same luthiers would immediately know by experience what advice to give me if I was copying a Martin dred. One thing I have considered is to make a unit where I can clamp on and remove tops. I could at least experiment with different sonic bracing patterns, or variations (thickness and width of braces, scalloping, etc.) that way.

[Quote]I can't tell from the drawing but are your structural braces in full contact with the soundboard or are they "flying" and only connected at the ends? If they ary in full contact, how are you dealing with the intersections of with the tone bars?[/QUOTE]

The structural braces are "flying" below the top by 1/2". There is almost no contact with the top. The only points of contact are at the extreme ends of the structural braces (waist, neck block. and tail block.) So, the last 3/8" or so of each brace will contact the top, and all of the sonic braces will have no contact with the structural braces. I'll post another drawing that might show it better.

[Quote]I like the looks of the guitar. It has a nice modern feel. [/QUOTE]

Thanks, I appreciate that. I am pleased with the body shape, the bridge is "function over form" all the way, and the headstock is likely to evolve from what I've shown. I fought with the notion that the bass string end of the bridge should be wider (a la Kasha), but could find no information to "prove" it. I gave the bridge an elongated almond shape to facilitate pivoting/rocking. I also suspect that with this rather large body, bass production will not be lacking. (I'm more worried about treble production, and dreaming of a balanced amplitude across the sonic capabilities of the strings.)

[Quote]With your bridge design, there really is no structural reason to run the strings all the way to the tail. There might be a sonic effect with the strings behind the bridge resonating.[/QUOTE]

My sonic braces will be light (1/4" wide by 3/8" tall, and scalloped at both ends. They would not be strong enough to withstand the shear force if I use a pin or pinless bridge. My idea is to allow the top to really respond to the string vibrations, and let the structural braces handle that shear force. I expect to need a small felt shim near the tail, beneath the strings, to stop unwanted (inharmonious) string resonance.

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[Quote]MichaelP
welcome onboard Dennis. I will be nice to have you with us [/QUOTE]

Thanks for the welcome, Michael.

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Dennis Leahy
Duluth, MN, USA
7th Sense Multimedia

[QUOTE=Mike Mahar]I can't tell from the drawing but are your structural braces in full contact with the soundboard or are they "flying" and only connected at the ends? [/QUOTE]

Mike, here is a larger sketch of the bracing, which may show up better. The small "dots" are just markers for me to use on the lexan template to drill some 1/16" holes, so I can make location dots with a pencil.

Again, the red lines indicate flying/floating structural braces (about 1/2" down from the top.) You may see some tiny lines that indicate where the braces do make contact with the top, near their ends only.

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Dennis Leahy
Duluth, MN, USA
7th Sense Multimedia

Dennis,
I’m happy you have brought these ideas to discuss here. Some of your ideas are familiar to me having many simmilar “what if” moments myself during my resent acoustic builds. I am curious if these changes from the norm will produce some new and useful information. I think the only way we will know is to build.
My teacher has told me that with a flattop, the bridges movements from the string vibration “float like a boat in water” (for lack of a better analogy) in many directions and if the strings are “anchored” somewhere other than the bridge, you could loose some of the punch your looking for. Maybe with the torque at the bridge, you still may get away with it.
Please build it, and we would love to hear your findings.

Wade

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Wade
Nashua, NH
http://www.wadefx.com

Dennis,

Glad to have you aboard.

[Quote=Wade S.]Dennis,
I’m happy you have brought these ideas to discuss here. Some of your ideas are familiar to me having many simmilar “what if” moments myself during my resent acoustic builds. I am curious if these changes from the norm will produce some new and useful information. I think the only way we will know is to build.
My teacher has told me that with a flattop, the bridges movements from the string vibration “float like a boat in water” (for lack of a better analogy) in many directions and if the strings are “anchored” somewhere other than the bridge, you could loose some of the punch your looking for. Maybe with the torque at the bridge, you still may get away with it.
Please build it, and we would love to hear your findings.

Wade [/QUOTE]
Hi Wade,

I agree that the only way to know if the ideas have merit is to build one. I promise everyone I'll be honest, even if the result is a complete flop. My intuition tells me that by taking the shear force away from the bridge, yet keeping the break angle, that a number of different bracing patterns may "work". My gut instinct is that this may actually be easier to voice than an X-braced guitar. (You can only shave the X-braces so much before the top fails, and the point of structural failure may still not be the optimal brace shape for tone.)

I take some comfort in knowing that radially braced guitars have been successful, as an example, here's a link to A J Lucas' radially braced steel string. (There is an MP3 file link on that page as well, just above the "specifications" section near the bottom.) A J Lucas Radial Guitar However, note that his bracing pattern is actually an X with radial tonebars, as seen here: Lucas bracing

My understanding of the bridge movement for pin/pinless bridges is mainly longitudinal rocking, with some side-to-side, pumping, and other complex motions thrown is as well. (I like the boat analogy.) I'm assuming that since 4 of my 6 strings will be wound, they will grip the saddle and the leading and trailing edges of the bridge "tunnels" well enough that this will act more like a pin/pinless bridge than a moveable/archtop bridge. I think one of the challenges will be to make sure I have enough strength in the sonic bracing to withstand the torque force on the bridge.

Should be an interesting experiment!

[Quote=Ronn Coates]Dennis,

Glad to have you aboard.[/QUOTE]
Thanks, Ronn! I have enjoyed and learned from watching your build on the Bubinga cutaway you just completed. Glad to see you here!

Dennis

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Dennis Leahy
Duluth, MN, USA
7th Sense Multimedia