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#1
10-11-2021, 04:48 PM
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Question for those who have voiced guitar tops
Hi every, first time posting, long time reader!
I just ordered a Recording King RO-328. I found a youtube video of the internal bracing, they look to all be pretty much just bandsaw cut and glued in, almost zero "peaked" or "pyramidal" shaping beyond the scalloping. I have an ibex finger plane and was thinking of just taking off a little of the extra material on some of the braces. Having watched a great many voicing videos, it seems the triangular or pyramidal shape retains the strength or stiffness of a square cut brace but allows for the top to move more due to the reduced weight. Im not trying to revoice the guitar, or reducing the brace height, or changing the scallop shapes or peak locations, I'm just wanting to reduce some of the weight to improve the efficiency of the strings vibrating the top. I have plenty of woodworking experience, but I've never voiced a guitar myself. Just looking for thoughts or opinions on this from more experienced builders. Thank you! Last edited by carabinerx; 10-11-2021 at 06:59 PM. 
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#2
10-11-2021, 06:24 PM
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Video is not working for me. I'm no expert by any means having only built 60 guitars but I try to do all the 'voicing' before the top is glued down to the body. And really that 'voicing' is really determining the optimal top thickness based on deflection testing and material properties of the wood.
Having said that I have indeed improved the tone of guitars I have built by reaching in and shaving braces. In fact once I determine the top thickness I always brace on the high side. That way if the guitar needs improvement I can make it. But I've only so far needed to do this on two guitars and it really did help. It's risky business though. On a factory produced guitar like that they have basically figured out what the mean average construction practice makes the best guitar. So if you have on of the ones that was built on the tighter side then shaving the braces would probably help, however; if it's on the light side then you might ruin it. So questions? What is it that you don't like about the guitar now? What is it that you hope to achieve?
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#3
10-11-2021, 07:11 PM
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Welcome to the forum!
Bryan Kimsey http://www.bryankimsey.com/music/lutherie.htm is the master of this art. He specializes in tweaking Martin guitars. Some years ago, on another forum, he was talking about the art and the very real potential of shaving too far and being left with a dead guitar. I have a Chinese made Guild GAD-30 which has a lot in common with the RK. However, the braces are scalloped. IMO, what is constricting my guitar (and yours) is the thick finish. If you could remove the finish (please don’t!), it might improve the sound. But I think that these guitars benefit from lots of playing which not only vibrates the wood, but vibrates the edges of the finish and frees you up the joints some. Also, Toneriting, in this case might help. (A Tonerite is basically a vibrator that works around the clock… there are many threads on AGF about them) This is all conjecture on my part. Bryan’s website has some further information and you may want to search other acoustic guitar forums for “shaving braces” . Good luck with this. Rick
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#4
10-11-2021, 07:16 PM
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This is from Bryan’s website:
Quote:
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”Lorem ipsum dolor sit amet” Last edited by srick; 10-11-2021 at 07:23 PM.
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#5
10-11-2021, 07:20 PM
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@redir
Thanks for the feedback! This is more exploratory and hypothetical. The guitar hasnt been delivered yet so I cant say. Im just speculating from all these builders, even martin and taylor, etc. who taper the tops of their braces. I fixed the videos, thanks for letting me know. In the second one, Dana Bourgeois shows how (in cross-section) a square brace and a domed/triangle shaped brace are the same in strength and stiffness for the top, but the triangle is almost 30% less weight, allowing the strings to vibrate the top more easily without sacrificing the integrity of the top. The first video just shows how blocky the braces are. This is a fairly inexpensive, Chinese-manufactured, brand so I don't know how much detail is being put into shaping the braces or voicing the tops (this company seems to sound and perform very well though! thats why I bought one). Im just building a connection that if rounding over the braces has little to no negative effect (according to these builders, and from my understanding) but a distinct positive one, that it may be worth it to gently reduce some of the excess material. Like I said, im not trying to revoice it, im not lowering the braces or. change nodal points, just taking off the seemingly useless extra material. Im mostly just hoping for some experienced feedback on that specific aspect of a brace's function. thanks @srick I did read that, thank you, but I assumed he was referring to scalloping along the length of the brace. Here's a diagram from taylor. I was thinking more in terms of the cross-sections on the right. Is that what he is referring to? I thought it was about the more impactful degree of scalloping on the left side of the page. https://www.yumpu.com/en/document/re...taylor-guitars Last edited by carabinerx; 10-11-2021 at 07:33 PM.
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#6
10-11-2021, 07:32 PM
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In case Dana B. didn’t mention it, before the braces are glued on, the top is very carefully thicknesses and thinned at the edges. This is a big part of the responsiveness of a guitar. When you get a bunch of luthiers together and ask them what provides the magic, it’s like a bunch of top chefs talking about their stew. One will swear by their bracing pattern, another will swear by Chladni vibration patterns, another by using certain varieties and patterns of wood; they all have their recipes. All the recipes are similar, but different, and the funny thing about it is that there’s more than a little magic involved.
I know the temptation to tinker around, I have that too. But the greatest improvements in tone will not come from the guitar, they will come from your fingers and your practice. Have fun with the new guitar and play it a lot! Rick PS - maybe it’s time for you to purchase a Martin kit and play around with some of your ideas from the ground up rather than risk damaging a new guitar?
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#7
10-11-2021, 07:37 PM
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Haha, youre probably right! I certainly have a bad habit of sticking my hands in everything when I dont necessarily need to!
Honestly, im just hoping to play it and be so moved I dont feel the urge to do a thing. Its getting a professional set up now and shipping out this week, which leaves me too much time twiddling my thumbs and watching youtube videos  This was more of a curiosity and a thought experiment, but I appreciate your input!
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#8
10-11-2021, 08:05 PM
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Quote:
But long ago, someone had leveled the frets leaving them really flat and low, especially from the fifth to the twelfth fret.. I am tempted to get some fretting tools and do my first refret, but the tools will cost several hundred dollars and the guitar is only worth that much. So I settled. It’s playable. Now that I got that out of my system, I’ll wait for my new guitar to be finished. And don’t feel sorry for me, I have a very nice Bourgeois 00 Country Boy which is my main guitar. But I do like having projects! Best, Rick
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#9
10-11-2021, 10:19 PM
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#10
10-12-2021, 06:58 AM
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Dont!
You'll get a really sore wrist and end up making not a tot of useful difference. The guitar is made to lie between a set of tolerances, those have been designed by the manufacturer to take account of the variation of stiffnesses in all of the woods they have selected. You have no way of knowing whether the core components were stiff or bendy, you may get a fantastic guitar, but if you don't you will never know whether it needs more adding (stiffer) or more wood shaving off.
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#11
10-12-2021, 07:32 AM
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My favourite fret hammer is a yardsale bodywork hammer that I double stick taped a piece of thick leather to the face, cost $2.50. I ground down $9 end nipper pliers to pull frets with. You can protect the fingerboard with masking tape. Clean out fret slots with a piece of hacksaw blade ground to a point. Glue or tape sandpaper to a flat board for levelling. There are $10-20 crowning files on amazon that work. In general look at tools you want then figure out how to improvise or make it. There are lots of tips on google and you tube.
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#12
10-12-2021, 09:59 AM
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Quote:
I have a cheap 70's Morris f15 that needs a refret to practice on. Last edited by carabinerx; 10-12-2021 at 10:25 AM.
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#13
10-12-2021, 10:33 AM
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Well I did find one answer!
"I drop different woods onto a steel table and listen to the sound they make, its a good indicator of which pieces will add brightness or other characteristics to the recipe you are creating in a specific guitar. The cross section of the finished brace does also seem to effect the tone quite a bit. A taller thinner brace, kind of fin shaped, will give a brilliant sound and a lower rounded or bullet shaped brace will be a warmer sound. So you can use those parameters to fine tune things regarding your tone bars. The stiffness is desirable not so much for tone, but for efficiency. The stiffer it is, the thinner I can make it and the lighter it becomes. The less mass there is, then it will take less string energy to set things in motions, thus resulting in a louder and more responsive guitar. I go into great detail about this important concept in the course about Guitar Physics. Let me know if you have any more questions, thanks! Tom (Bills)" Edit: this is exactly what I was looking for: "So in comparison with a rectangular brace of the same width and height, a triangular cross-section brace would need to be either three times as wide or ~ 1.44 times as high to obtain the same stiffness. Note that 1.44… is the cube root of 3. If you now have the same stiffness for both cross-sections, what have you gained or lost in terms of the triangular brace being heavier or lighter than the rectangular one? Since both cases use the same material, the weight per unit volume of brace is constant. The cross-sectional area of the rectangle is simply Ly*d, while that of the triangle is 1/2*Ly*d. If we make the base of the triangle 3 times wider than the rectangle to achieve equivalent stiffness, then the area of the triangle is 3*1/2*Ly*d, or larger than the rectangle by 50%. If we make the height of the triangle 1.44 times taller to achieve equivalent stiffness, then the area of the triangle is 1.44*1/2*Ly*d or 0.72*Ly*d. So it’s clearly more effective from a weight standpoint to make the triangular brace taller rather than wider to achieve the same stiffness. Making the triangle taller rather than wider achieves a reduction in the braces’ weight by ~28% while achieving the same stiffness as the rectangle. Now the builder needs to make a personal choice about whether it’s more difficult and/or important to" https://ukuleles.com/applying-techno...ations-part-i/ Okay so I will not mess the braces then! Thanks for everyone's input! Last edited by carabinerx; 10-12-2021 at 10:39 AM.
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#14
10-12-2021, 12:37 PM
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Braces make up a very small amount of the total weight of the guitar top but rounding them off could possibly make a difference I suppose. But mostly when you hear about luthiers shaving braces they are doing so to reduce the stiffness rather than weight.
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#15
10-12-2021, 03:46 PM
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Quote:
Rick
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