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| classical guitar top and back radius http://luthiersforum.com/forum/viewtopic.php?f=10101&t=19214 |
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| Author: | Rond [ Thu Oct 16, 2008 12:55 pm ] |
| Post subject: | classical guitar top and back radius |
Hello, What is the typical radius of the top and back of traditional Spanish guitars? As for the top in the Bogdanovich book it mentions 25' giving a 4mm ramp where as in the Courtnall book it shows the Romanillos Solera with a 3mm ramp. Would this mean that the Romanillos radius is more shallow 20' or so? As far as the back I have no idea but I read somewhere that it is typically a smaller radius. Ronald Canada |
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| Author: | Jim Kirby [ Thu Oct 16, 2008 2:00 pm ] |
| Post subject: | Re: classical guitar top and back radius |
Ronald - Greetings to OLF! It's probably deceptive to think of the classical top as being radiused. Usually, the top is flat from the lower transverse brace (or general vicinity of the soundhole) forward, and flat around the perimeter of the lower bout as well. They are domed in the region of the bridge and central lower bout, and this dome is created by the hollowing of the solera in this region (see Courtnall). Variants include the Bogdanovich (Romanillos, other?) style where the doming in the top is created by having the lower bout perimeter fall away from the plane of the initial flat top, rather than by having the top project above this plane. Further variants would include the raised fingerboard where the top has to fall away drastically in the upper bout, relative to the initial flat plane. None of these are any sort of uniform radius. For the back, 15' or so is good, maybe flatter on a large bodied guitar. Jim |
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| Author: | Mike Collins [ Thu Oct 16, 2008 2:22 pm ] |
| Post subject: | Re: classical guitar top and back radius |
Hello Ron; As far as what the Sp. Makers use i do not know. I've seen many different back radii from different makers. Also I've seen flat backs!!  I use a 30' on all my fans & the # 2 brace-the one just below the s.hole. The upper brace under the fingerboard is flat! I use 25' for my backs! mike |
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| Author: | WaddyThomson [ Thu Oct 16, 2008 3:01 pm ] |
| Post subject: | Re: classical guitar top and back radius |
From the information I gathered, and what I used, regarding the Romanillos top, was that it was both lowered on the wings of the lower bout and as Jim said, flat around the edges of the lower bout but, then was domed at about 25' starting in about 15 - 20 mm from the edge. It makes for a very lively top. I used about 25' on the back, but it is tapered toward the heel by a good bit. |
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| Author: | Claire [ Thu Oct 16, 2008 5:05 pm ] |
| Post subject: | Re: classical guitar top and back radius |
Hi Ronald, Welcome to the OLF. Someone correct me if i'm wrong: What Waddy is describing about the Romanillos top sounds like something i saw on an old Conde. Although, when looking at the actual guitar, the conde actually dips in from the sides rather than being flat, and then domes outwards in the midlle As well as being domed from the lower harmonic bar to the end block. This gives the top sping tension in three directions rather than the usual two, making for a stiffer more lively top. As well as countering the production of wolf notes, theoretically. I just finished making the Bogdanovich solera yesterday. I like the idea of it for various reasons, AND i'm really liking the Romanillos solera description quite a bit. That will have to be a future project. Typical back radii is 15 ft for a classical. Flamenco guitars have a larger radii.....20- 25 ft. Cheers, Claire |
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| Author: | Robbie O'Brien [ Thu Oct 16, 2008 5:53 pm ] |
| Post subject: | Re: classical guitar top and back radius |
What Jim, Mike, Waddy and Claire said. ![[:Y:]](./images/smilies/smiley20.gif "Thumbs Up")
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| Author: | Rond [ Thu Oct 16, 2008 6:09 pm ] |
| Post subject: | Re: classical guitar top and back radius |
Hello and Thanks for the welcome About the Bogdanovich Solera. If the lower bout is lowered instead of raising the bridge area from the original plane doesn't this make the area adjacent to the lower bout remain flat . Why are Flamenco back more radius than Classicals; how does this extra doming affect the tone and volume. Ronald |
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| Author: | Mike Collins [ Thu Oct 16, 2008 6:19 pm ] |
| Post subject: | Re: classical guitar top and back radius |
If the back is very stiff-it helps to accentuate the trebles! Ala--Flamenco!! Ola!!  MIKE |
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| Author: | Mike Collins [ Thu Oct 16, 2008 6:21 pm ] |
| Post subject: | Re: classical guitar top and back radius |
[quote="Rond"]Hello and Thanks for the welcome About the Bogdanovich Solera. If the lower bout is lowered instead of raising the bridge area from the original plane doesn't this make the area adjacent to the lower bout remain flat . Wow! I can not follow your thinking on this! Can you re- word it ?? mike |
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| Author: | Rond [ Thu Oct 16, 2008 6:38 pm ] |
| Post subject: | Re: classical guitar top and back radius |
[quote][/quote] from Jim kirby Variants include the Bogdanovich style where the doming in the top is created by having the lower bout perimeter fall away from the plane of the initial flat top, rather than by having the top project above this plane. When trying to picture this mentally that's what I came up with; that the bridge area remains flat. Obviously this is all new to me . I am trying to understand some of it. Ronald |
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| Author: | Jim Kirby [ Thu Oct 16, 2008 6:54 pm ] |
| Post subject: | Re: classical guitar top and back radius |
Rond wrote: Quote: from Jim kirbyVariants include the Bogdanovich style where the doming in the top is created by having the lower bout perimeter fall away from the plane of the initial flat top, rather than by having the top project above this plane. When trying to picture this mentally that's what I came up with; that the bridge area remains flat. Obviously this is all new to me . I am trying to understand some of it. Ronald Ron - The flamenco back is flatter than the classical (according to Claire) look again. I think my Reyes flamencos are 18' radius, which is probably the same as the Rodriguez copies I've built. The original instruments probably didn't have spherical backs - I think we're projecting that on them from our steel string world. Bogdanovich - yes, the bridge area is basically in the plane of the upper bout, with the rest of the lower bout falling away from there to give a 4mm or so overall doming. Claire - for the Bogdanovich solera, try the Romanillos trick of putting the top inside the sides. You need to cut a 2mm trough between the form side and the raised wedge so the slide can slip in. Reason? The top edge of the side is flat and doesn't have to be tapered to sit down on the top as instructed in Bogdanovich. After I thought about this (thanks Waddy, David and others), I spent about 10 seconds deciding to go this way. It is so much easier conceptually. |
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| Author: | Martin Turner [ Fri Oct 17, 2008 2:01 am ] |
| Post subject: | Re: classical guitar top and back radius |
Doming on my classical tops starts just forward of the bridge and extends over the lower bout with a flat profile where sides meet the top. The bottom of my bridges need a little bit of profiling to fit the top. Radius of the top isd around 25' and my backs are shaped to a 15' radius. |
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| Author: | David LaPlante [ Fri Oct 17, 2008 6:34 am ] |
| Post subject: | Re: classical guitar top and back radius |
Attachment: fixtures 001.jpg This is basically the Romanillos Solera. I've added the shaped form as we just used right angle brackets at the course. Since this photo was taken, I've segmented the form and made the pieces a bit more adjustable in and out. As you can see, the area in front of the second harmonic bar is basically flat though a little relief is built into it to facilitate a smooth transition into the more pronounced dome at the back. The doming as well as the "drop" of the top starts just below the waist and tapers from zero up to 5mm at the end block. a subtle benefit of this is that there is a bit less of an angle at the neck/body join as the bridge height can be maintained at around 10mm despite the doming due to the corresponding drop. the neck "lift" is about 2mm. The back radius used (and actually the radius of the domed section) translate to about 25'. |
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| Author: | WaddyThomson [ Fri Oct 17, 2008 10:30 am ] |
| Post subject: | Re: classical guitar top and back radius |
Here is a picture of a Romanillos style solera showing how the sides are butted to the outside edge of the top. You can see the raised lower bout wedge on the right side where there is no side. Attachment: P1000415.JPG Here is what it looks like after attaching the sides. Now, just trim the sides down to the top. Any gaps will be covered with binding and purfling, and it leaves a larger amount of linings, or in this case, dentellones/tentellones, attached to the top. Attachment: P1000485 (Large).JPG Here you can see the raised lower bout and the scooped out area, which I had to fix with bondo, due to doing it wrong the first time. This was when I was trying my side bending on a test piece of Poplar the first time I bent anything on a pipe. Attachment: P1000289.JPG David's solera reminds me a lot of the Bogdanovich solera with the exception of the gap between the mold and the raised solera. Sure beats trying to tweak the sides to fit the slope of the top, if you ask me, and you didn't. |
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