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| "Cylindrical" top arching methodology/reasons? http://luthiersforum.com/forum/viewtopic.php?f=10101&t=18530 |
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| Author: | eugeniodilampp [ Mon Aug 25, 2008 8:56 am ] |
| Post subject: | "Cylindrical" top arching methodology/reasons? |
Dear my friends, Recently I am reading about the guitar builders who their tops arch only one direction. Is it possible for to make a comment how do they this? why they choose this way instead of the 15+ arching dome? has made anybody a "dish" arching one direction only? grazie, Eugenio |
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| Author: | Michael Dale Payne [ Mon Aug 25, 2008 9:03 am ] |
| Post subject: | Re: "Cylindrical" top arching methodology/reasons? |
It would seem to me that for this to happen the top would need to have braces profiled only to form a cylinder. That only leaves pretty much ladder style bracing. in my mind |
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| Author: | Dave White [ Mon Aug 25, 2008 9:26 am ] |
| Post subject: | Re: "Cylindrical" top arching methodology/reasons? |
Check out Howard Klepper's bracing. I'm sure he'll be along to explain it better. He reason's that you already have enough stiffness longitudinally and only need to arch laterally - he calls it a spline curve rather than a cylinder. He shows different top bracing patterns on his website, one of which is X braced one of which isn't. |
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| Author: | Howard Klepper [ Mon Aug 25, 2008 11:47 am ] |
| Post subject: | Re: "Cylindrical" top arching methodology/reasons? |
It's easy to make a spine curve workboard. I take a sheet of 1/4" tempered hardboard (Masonite), screw it down along its centerline, and support the edges with dowels. The amount of curvature can be controlled either by changing dowel size, or by moving the dowels in toward the centerline. Any style of bracing can be fit on this workboard--but you need to fit it to the place where it will go on the guitar, since unlike a radius dish, the curvature is not the same in all locations or all directions. And if you wanted to motorize sanding, you would need to make the board oscillate fore and aft. I don't motorize sanding, but I have gotten good at ballparking the braces with a small plane. See Jon Sevy's site for an explanation of spline curves. I have the link somewhere, but you can Google it. BTW, I have become unsure whether lateral arching adds more stiffness latitudinally or longitudinally. But I like the sound I'm getting. |
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| Author: | eugeniodilampp [ Mon Aug 25, 2008 10:16 pm ] |
| Post subject: | Re: "Cylindrical" top arching methodology/reasons? |
Dear Mr Howard, Much thanks for you take the time to explain your system. Is your board the size same of your width of guitar or larger? I am building the classical guitars and must shave bottom of the fretboard over the body to make it sit flat thanking angle of the neck, does your spline curve system need more shaving? much much thanks, Eugenio |
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| Author: | WaddyThomson [ Wed Aug 27, 2008 10:06 am ] |
| Post subject: | Re: "Cylindrical" top arching methodology/reasons? |
It is going to be different on a classical guitar Eugenio. On most classicals, the lower bout is domed a bit, but the upper bout is flat. Also the neck angle on a classical is different from the neck angle on a steel string. You are right that you will have to sand the underside of the fingerboard over the upper bout. I did that by sticking some sandpaper to the upper bout, sandy side up, and shimming the fingerboard on the neck with another piece of the same paper turned upside down so the board would slide around on it, then I just used small strokes from side to side the get the angle in the area over the upper bout. If you use self sticking sandpaper, I suggest that you stick it to some easy release tape first. The sandpaper sticky stuff is too sticky and will pull fibers off the top. The angle is small, and it does not take a lot of sanding. |
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| Author: | John Hale [ Wed Aug 27, 2008 11:05 am ] |
| Post subject: | Re: "Cylindrical" top arching methodology/reasons? |
Do different arching methods and radii affect the tone or is it more structural? |
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| Author: | Laurent Brondel [ Wed Aug 27, 2008 11:56 am ] |
| Post subject: | Re: "Cylindrical" top arching methodology/reasons? |
I can see how the section of a tube is stronger, longitudinally, than the section of a sphere. According to some, flexibility across the grain tends to increase bass response, I've verified this with various bracing patterns. I would be curious to hear Howard's comment on this, if his guitars built with a spline curve on the plates tend to be more focused, tonewise. |
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| Author: | Howard Klepper [ Wed Aug 27, 2008 1:14 pm ] |
| Post subject: | Re: "Cylindrical" top arching methodology/reasons? |
eugeniodilampp wrote: Dear Mr Howard, Much thanks for you take the time to explain your system. Is your board the size same of your width of guitar or larger? I am building the classical guitars and must shave bottom of the fretboard over the body to make it sit flat thanking angle of the neck, does your spline curve system need more shaving? much much thanks, Eugenio Eugenio, that is a hard question to answer; a lot depends on your construction method and neck angle. A short answer would be that with a spline or cylindrical top, more wood must be removed from under the board right at the edge of the body, but no more wood must be removed at the end of the board near the sound hole than with a spherical top. Another answer is that it is easier to shape the underside of the board with a top that is only curved laterally, because the edges of the board define straight lines, and the relief can be put in under the board with straight strokes of a curved scraper. Another answer is that you only need contact with the top near and at the edges of the board, and can be imprecise with the relief under the board toward the center of the board (this is true with any top arching system). The last answer is that I like to build classicals with an elevated fretboard extension in the style of an archtop guitar, with a joined neck; but this style of elevated board with a neck extension under it is difficult to execute using the traditional single piece neck and headblock with inset sides. |
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