A top bracing pattern for your critique

[Kim]

Following the same philosophy applied to the back bracing of my guitar, insomuch that I am trying to inject some of those things that I have been chewing over for the last few years and ignore convention, I present my top bracing pattern.

Like the back, what I am seeking to achieve here has little to do with seeking out a particular tone. Rather, at this stage I am attempting, in my own way, to utilize as much area of the lower bout I can in order to amplify the strings energy as efficiently as possible, nothing new in that.

By doing away with the conventional angled tone bars, I seek to spread tension from the rotational force at the bridgeplate into the rear parabolic and fan braces.

It is my hope that this spreading of the tension will introduce the strings energy more evenly into the top and out across more of that area behind the bridge and the rear legs of the x brace. With what I hope to be a more balanced, less inhibited outlet for that energy, I theorize that it will be converted more efficiently to excite the diaphragm. We will see .

Everything at the lower bout tapers to nothing. The finger braces which angle in toward the parabolic running behind the maple bridge plate are thinner and lower than those angling toward the front of the bridgeplate. I have lightened these particular braces in an attempt to make the top just a tad more flexible in the waist in the hope that it will keep the lower legs of the X a bit looser and encourage the pump.

The top is currently 2.8mm at the soundhole/bridge area and feathers to 2.5mm at the linings. The X is 7.5mm wide at the lap joint and app 15mm tall. However after the first 20mm of each leg from the centre, the height of the X brace sweeps to taper inline with the dimensions you may expect in a parabolic tapered brace 13mm high at it's centre. The width of the X brace legs also taper evenly from 7.5mm at the centre to finish around 5.5mm near the linings.

The bracing is Adi and the top is a nice 2A Adi that was given to me by Paul Burns (ex Steve Roberson Colonial Tonewoods) as a thanks for some toggle clamps I sent him a while back. (Thanks Paul, here's to you M8 ) I chose this particular top because of the stiff compression grain in each plate that will run nicely under the wings of the bridge and offer support against rotation.

In that vein you will notice that the soundhole support braces have also been omitted and replaced with a full cross grain patch as you would find on one of Lowden's or a Dave White's fine guitars. Generally, I have found that a guitar ruined by a rotated bridge will display a larger belly or dome than normal in the soundboard behind the bridge. Naturally enough for that area to lift or dome the area between the bridge and soundhole must collapse giving a kind of a wave effect to the top when looking from one side to the other. With traditional braces around the soundhole, it is MHO that this becomes the weakest point of a guitar top and invites bridge rotation. I consider that if you wish to get away with lighter bracing in the lower bout for the long term, you must address that weakness and I think that the full soundhole patch goes a long way toward this goal.

Anyhow, enough of my "out trumped conjecture" (Thanks Dennis ), here is my top. Please, please feel free to express your true feelings about my design in this thread, if I could not take constructive criticism, I never would have posted this. Equally please, please do not be offended if I choose to not take your advice, but I must add, after reading some of the great input in my "back bracing pattern" thread, I have reevaluated and will be making some suggested changes. Ain't the ANZLF a great place




















Cheers all.

Kim

[Dave White]

Kim,

Interesting stuff. In essence I think that's what Rick Turner does - I've seen him post that he uses three fan braces instead of the two tone bars.

I agree with the soundhole patch - of course

"Like the back, what I am seeking to achieve here has little to do with seeking out a particular tone. Rather, at this stage I am attempting, in my own way, to utilize as much area of the lower bout I can in order to amplify the strings energy as efficiently as possible, nothing new in that."

That statement puzzles me a bit though. Ultimately it has to be about a certain sound. If you take your statement of intent and conventional interpretations of "efficiency" then you would be making a Smallman type top. In my mind it is about "effectiveness" as much as it is "efficency". Your bracing looks good to me in terms of my style of building and sound I would be looking for.

The proof of the pud though . . .

[Kim]

Kim,


That statement puzzles me a bit though. Ultimately it has to be about a certain sound. If you take your statement of intent and conventional interpretations of "efficiency" then you would be making a Smallman type top. In my mind it is about "effectiveness" as much as it is "efficency".

Dave, sorry for the confusion, I was sort of suggesting that as this is the first, I have no real direction or bench mark to head for other than to get as much sound as possible out of the guitar without it actually imploding. If I am happy with the outcome, I will then focus toward tonal improvements if not I will need to make some changes. At the same time, whilst I am hoping for a responsive guitar, I also want enough headway from it to withstand a firm dig of the pick without loosing too much clarity and separation.

Your bracing looks good to me in terms of my style of building and sound I would be looking for.

The proof of the pud though . . .

I am extremely happy to read that coming from you Dave. As I have said before, you have been an inspiration to me for a number of years now and remain one of the reasons I have maintained an interest in this craft for so long. Your workmanship is always first class, and your style refined and innovative. And yes, I agree the proof certainly is in the pud

Cheers

Kim

[Hesh1956]

Kim bro your top looks excellent!!!!



And how true your statement is that you wrote on the top.

Here are my impressions:

1) Unlike the vast majority of builders, me included, you did NOT over brace this top falling into the trap of thinking that you were building a bridge, building, etc. Your bracing is light enough that the top must ring pretty well as is.

2) The bracing pattern looks very cool to me and not just the pattern and shapes - I think that you are going to have a great sounding, balanced guitar.

3) I like the over-sized, curved, beveled bridge plate. You see over-sized bridge plates from many of the best known builders i.e. Somogyi and others who use thin tops.

4) I did the math and if I did it correctly your top is .110ish around the sound hole which should be fine. IMHO you could have gone thinner knowing that this is Adi but I don't think that .110 is going to be too thick either. Funny thing about thin tops is that a thinner top may be able to move and pump more but there is less material to resonate too...... The trick is the perfect balance and if any of us knew what that was for each particular top we wound not be on guitar building forums......

5) Neatness: Superb!

6) You have married a number of very good ideas, parabolic braces, fan pattern, double thick around the sound hole, over sized plate and you know what they say about good ingredients when cooking..... this is going to be a great sounding guitar.

Kim if I were to give you a grade for this top and your thoughtfulness and effort your grade would be a A+.

I have no suggestions for you as to something that I would do different. Instead I believe that you may have nailed it the very first time and I am very interest to hear how the guitar turns out now.

Way-to-go!!!!!!!!!!

[Dennis Leahy]

I don't know anything, so I can't say anything...


Oh, what the hell! First, I'm very pleased to hear Dave and Hesh giving you the thumbs up on this. As Hesh noted, most "first" guitar tops are overbraced as if they might also need to be used as the foundation for a skyscraper - and you did not fall into that trap. I like your logic about preventing the waveform distortion from taking place. If the lower bout bellies/bulges a little bit over the course of time, it should be very small (and easily assuaged by a crank on the lower bolt or setscrew of the adjustable neck I fully expect to see on this guitar. )

What wood species did you make the bridge plate from, and what is the grain orientation? (You see, I have learned by observation to ask quasi-intelligent questions that may provoke further discussion. Unfortunately, since I have no experience with bridge plate material or its grain orientation, I will be of no help - but I may learn something!)

If the prediction of a newbie is of any interest, I predict that once the Adirondack Spruce has a chance to relax a bit, you'll have a guitar with power, sustain, and better than average bass. I am still trying to wrap my head around the engineering/physics that will bolster trebles without sacrificing bass, as well as how to achieve tonal balance, so I don't have a sense of what you have in that regard. Who knows, this may be the pattern everyone will be copying!

Dennis

[Allen]

I've got nothin' to add other than top notch workmanship. It looks like you've removed anything that isn't going to help tone, and left it where strength is required.

In fact I think that this pattern has some really good features that are worth pursuing on one of my future guitars.

[Arnt]

I think the bracing looks fine, although personally I'm more of a 'Martin sound' guy so I use a variant of the slanted tone bar system. I have read that Larrivee (who now uses a different symetrical system) at one point tried a 'open' fan bracing behind the X, much like this, but he abandoned it in part because the top would ripple along the fan braces.

I taper everything behind the X in my system down to nothing too, but above the X I let the A-brace into the upper X brace arms at full height, I think this helps tremedously with the rigidity in this area.

[kiwigeo]

My first impression....an interesting marriage of of classical and steel string bracing.

My only comment, like Arnt I'd be watching for distortion of the lower bout.

[Craig]

Hi Kim,

Beautiful neat work mate,,,,,,,,,outstanding in fact.

I do wish you had built a more conventional bracing pattern for your first . A pattern proven to work .I only say this as you're a good mate and would hate to see you suffer disappointment from your No. 1 guitar.

The cross and finger bracing , transverse, bridge patch, sound hole area all look good to me, and of course I'm a big fan of the A Frame set-up. Those light fan braces concern me on a steel string, although I hope I'm dead wrong in that dept.

The real test will be after your've strung it up, it's all conjecture until then,and I'm hoping for it to be a killer of a guitar.

cheers , Craig

[Paul B]

I thought that top looked familiar, having looked at the pix before reading your post. You've certainly done it justice.

Nice clean work, the size of the bracing looks about right. I think it's going to sound great once that top opens up.

Oh, and those toggle clamps have been invaluable on my last couple of builds.

[Bob Connor]

Nice work Kim.

I guess you'll know in 6-12 months time whether the fan bracing is going to be adequate strengthwise.

What gauge strings are you planning to put on this?

The Mario brace should add quite a bit of stability to counter rotational bridge forces.

I'm sure from the look of it it'll sound fine. Certainly doesn't look overbraced.

Bob

[Kim]

Thanks for the kind words all,

Hesh, I need to thank you especially because I have picked up a lot from you over the last few years. For me it is not just what you have shared with us from your own shop, it has been those all so carefully posed questions that you present to others that have a special knack of extracting the all important detail so valuable for many newbies. In other words you concentrate more on not so much of the "what do you do" questions that are ask by someone who needs a fix, but more on the "why do you do" questions that are asked by one seeking to learn and avoid the need for a fix in the first place and because of this we have all learnt much together.

Dennis, the bridgeplate is hard maple about .90" the grain orientation is lateral and just off 1/4

Allen, thanks mate that is a huge compliment given the outstanding quality of your own work.

Arnt thank you, I was not aware that Jean Larrivee had done something similar, however I guess nothing is new. I would say that your method of in-letting the A-brace into the X would indeed stiffen up that area much more than the standard flat sticks.

Martin, I guess there is a bit of fusion between classical and SS going on there. This pattern relies more on that parabolic behind the bridgeplate as apposed to the V braces found at the back of the fingers of the fan on a standard classical guitar. It is my hope that the above-mentioned parabolic will act as a manifold presenting the tension to the fingers and the top in between over a greater area. I also hope that it will act as a buffer firming the top against excessive rotation in the first instance and thereby avoiding the rippling effect you and Arnt mention.

Thanks Craig, once again having you comment on neatness is a big pat on the back for me. After all, your our very own resident neat freak and the cleanest most meticulouse wood worker I have ever seen...well not you personally, your a Kiwi and probably have a woolly crouch for all I know, but your work I mean

I do wish you had built a more conventional bracing pattern for your first . A pattern proven to work .I only say this as you're a good mate and would hate to see you suffer disappointment from your No. 1 guitar.

Anyhow M8, this statement is precisely why I did not ask anyone here first and just went ahead and made my top the way I did. I really did not want to be talked out of this and the respect I hold for the opinions of the people on this list could easily have caused that to happen. If this top fails I really am fine with it because I would have found the bear and learnt from the experience.

I can always put another top on it and next time, maybe look at a light double X or an Ervin type lattice. What ever I do I remain at this stage completely unconvinced that the conventional angled tone bars are the best solution for, what I believe, is the single most important area for sound generation in a guitar top. I will never say never, in fact my next may indeed be to traditional plan, but I will continue to focus on this area until I am happy, which will no doubt be never

Paul, thanks for the support and the top buddy it was the perfect choice for this experiment, I am kind of counting on the stiff compression grain running either side of the bridge to cheat the piper so to speak. Glad to hear that the clamps came in handy.

Bob, I am working on 12's or lights as that is what I have lots of thanks to the OLF group buy. 6 to 12 months, why yes, I guess hibernation could last that long, but when they wake up, they wake up very hungry

Once again, thanks all for your input.

Cheers

Kim

[joel]

I like it. Love the look too. I have absolutely no practical experience either, but I hope it turns out like you want it to Kim. Really looking forward to hearing how it turns out.

[matthew]

Kim I too know nothing of guitar bracing ... but MY instinct would have told me to do the reverse of what you have done; bracing the top a bit like you did the back, with tapering braces radiating out from under the bridge, making the lower bout a "drum" with a heavier reinforced centre.

Then the back I would probably have done like you did the top; it looks stiffer and stronger, with the bracing going right through into the upper bout.

But then, I know little of guitar mechanics and the physics of the pull stresses from the bridge plate. I suppose my instinct would be more suited to a guitar style with strings anchored in the tailpiece.

Anyway its a good thing I'm not making guitars, I think. Then again, if you alway do what you've always done ...

[Dominic]

Kim, nice work. I think its great that you are happy to push things. I don't for one minute believe that guitar design is in some long-term equilibrium where there is no room for improvements or even total revolution. What worked for martin in 1930 was in part due to the materials they had access to. Times and access to materials change as does the type of music played.
There are a range of designs that all work at some level and this is what makes it so much fun. Copying is a great way to learn but for me trying new things is part of the challenge and that make it exciting.
There was a balsa wood violin in the GAL journal a few issues ago where the guy applied his boat building skills to the project. And from reports it blew away some of the pros. There is stuff out there to be discovered, lets go.
Dom

[Craig]

BRAVO ! Dom.


Cheers , Craig

[Allen]

Actually, I'm with you on trying something totally out of the norm Kim. If I had a bit more patience I would devote more time and energy in thinking something like a brace pattern out, rather than getting on with building something that is rather tried and proven, and well...safe. I've been more daring with tops and brace wood than most, so I guess thats were we have a similar "rebel" streak.

And at the end of the day, if you don't try, how will you ever know?

I'm still blown away by how neat and "finished" your work is. Good on ya!

[BillyT]

Yeah! That's looking well worked over! Very clean Kim!