Top thickness taper question... (Full Version)

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TANúñez -> Top thickness taper question... (Apr. 5 2013 21:32:41)

Curious to know how far in from the edge do you all begin to taper your tops if you leave them thicker in the center and taper to a thinner thickness along the edge. For me it varies but generally mine around 40 to 50mm's around. Sometimes more, sometimes less.




estebanana -> RE: Top thickness taper question... (Apr. 6 2013 4:14:26)

Is this a religious question?




Anders Eliasson -> RE: Top thickness taper question... (Apr. 6 2013 7:30:48)

I dont taper before assembly.
And my finished guitars have little taper. some 0,2mm towards the edge.

You always end up taking some thickness of the edges when you scrape or sand the bindings. Thats why i dont thickness before assembly. After scraping/sanding bindings, I control the thickness of the soundboard with a Hacklinger guide and if necessary, I take of a bit here and there.
In general, the tapering starts some 5 - 6 cm from the edge of the guitar.

I hope this give you some kind of answer. I dont find it to be a religious theme, but yes, a pretty important one.




TANúñez -> RE: Top thickness taper question... (Apr. 6 2013 13:42:26)

I don't recall if we've ever discussed this here before or not so thought I'd bring it up. Usually, I thickness the underside of the top, before glueing the fans. Never have tried tapering it from the top side. Even though you are right Anders, that some thickness comes off when scraping the bindings.




Tom Blackshear -> RE: Top thickness taper question... (Apr. 6 2013 17:00:00)

it really depends on what top design you are using and what type of tone you are going for. Not all guitar tops are graduated the same way. But the basic technique is to sand around the outer edges for a higher frequency and in the center of the top for a more bold sound. Sanding around the edges will lower the top's key to some extent, usually enough to get right at the proper key for that design.

But top graduation in general is a learned process that can have interesting results, depending of the style you are building. Most guitars graduated in the center usually have better projection in their mid range, so it is really a matter of balancing the two together or one or the other, depending on your style of building.




TANúñez -> RE: Top thickness taper question... (Apr. 6 2013 18:57:45)

Right now I'm buildiing a classical. The Romanillos design, for a friends Father's birthday gift. I've never built off of this plan before. The edges are thinner but I'm not sure if Romanillos took it off from the underside or the top of the soundboard. So far, I really like this design and I'm planning on building more of them.




Andy Culpepper -> RE: Top thickness taper question... (Apr. 7 2013 1:15:19)

I don't taper before assembly either and these days I don't taper much at all. I taper more on a classical. IIRC Torres had some pretty drastic tapers like 1 mm difference between edge and center.
On a flamenco I usually take the top down to just about 2 mm so there's not a lot of room to taper without taking the edges too thin.
I brace the top at about 2.25 mm and do all my graduation and thinning from the outside once the box is assembled and before I glue the bridge on. Then I may take more off the edges while I'm playing it in the white.

Another variable is how much to taper to the sides of the bridge, or in front and behind the bridge, etc.
On a classical I'm coming to the idea that you want a more even stiffness gradient radiating from the bridge than you do on a flamenco. On a flamenco I loosen up the end-to-end flapping of the bridge a little more across the grain.




Tom Blackshear -> RE: Top thickness taper question... (Apr. 7 2013 4:39:32)

quote:


Right now I'm building a classical. The Romanillos design,


I wish you well, as Jose approaches it more with a esoteric vision than a specific thickness in mind. There is a way to determine the thickness but with a difference in fan brace size, etc. The first copy I built was different but very good with my changes made in the top's thickness and brace sizes.

Richard Todd bought that guitar and played it for years. It was a cedar top and Brazilian rosewood classical. Call me and we'll talk about it.




Anders Eliasson -> RE: Top thickness taper question... (Apr. 7 2013 7:32:36)

TANuñez

One thing about the Romanillos design:
Be carefull with the pressure you put on the 7 fan braces when you glue.
They are 3,5mm wide and 6mm high if i remember right.
This means that the down pressure you put on the braces (using clamps or go bar) gets very concentrated and therefor the braces easily gets imprint on the other/outer side of the soundboard.
Compare to a Torres/Hauser design, which has fan braces 3mm high and 7mm wide.

Thats one of the reasons the soundboard is very thin on the original. In order to not make a guitar which is to stiff. Its a design that very easily gets to stiff and tough to play. So its actually a complicated and very advanced design, where you need to know how to work to the limits. Since the stiffness of the bracing is so high and the top thin, on this design, I taper very little. Just some 0,1mm.

Its also a very good guitar to learn from. Small and potent and VERY different from a flamenco guitar.




britguy -> RE: Top thickness taper question... (Apr. 7 2013 13:17:57)

quote:

Richard Todd bought that guitar


You mean, Richard Todd, the British actor?

Didn't know he played guitar. . .

Interesting. Amazing what one learns in this site. . .




Tom Blackshear -> RE: Top thickness taper question... (Apr. 7 2013 13:58:03)

No, Richard Todd, one of Robert Guthrie's graduate students in Dallas Texas, who has gained a fairly good reputation as a classical guitarist.........

A Tennessee State University faculty member since the fall of 2000, Richard Todd received the B.M., summa cum laude, in Guitar Performance from the University of Cincinnati College-Conservatory of Music, the M.M. in Guitar Performance from Southern Methodist University, and the D.M.A. in Guitar Performance from the University of North Texas. He also studied extensively with world-renowned guitarist Matteo Mela in Cremona, Italy. In his formative years he earned a number of awards, including First Prize in both the Music Teachers’ National Association Competition and the National Federation of Music Clubs Competition.

Dr. Todd teaches guitar, music history and music theory courses. He also serves as Strings Area Coordinator. In addition to his teaching duties, he maintains an active performing career. Soundboard Magazine has described his playing as “subtly brilliant,” displaying “rich tone, effortless phrasing and a masterful use of silence.” Since 2009, he has been regularly performing in duo with Atlanta-based guitarist John Huston (www.hustontodd.com). The Fort Worth Star-Telegram described the duo as displaying “considerable energy and impressive virtuosity.” Their debut recording, Pura Vida (www.soundset.com), features a wide range of Latin American works for two guitars. Recent duo performance highlights include the Fort Worth Guitar Guild Music Festival, the Festival Mediterraneo della Chitarra in Cervo, Italy, and the University of Louisville Classical Guitar Festival. Dr. Todd also directs both the annual Tennessee State University Classical Guitar Seminar and the Virtuoso Showcase Classical Guitar Series, which takes place at the Nashville Main Public Library. The series features great guitarists from around the world.




TANúñez -> RE: Top thickness taper question... (Apr. 7 2013 16:22:19)

Thank you guys for your input. This will help me a lot with this build. I'm excited to be doing something completely different.




estebanana -> RE: Top thickness taper question... (Apr. 7 2013 21:46:00)

And now for something completely different....




constructordeguitarras -> RE: Top thickness taper question... (Apr. 8 2013 3:43:57)

I mark the bridge location on the inside and taper out from there.




El Burdo -> RE: Top thickness taper question... (Apr. 8 2013 8:44:25)

Thank you Mr. Blackshear for a clear explanation of what tapering does that I've seen. It's all too much!! I wonder if someone could do some Chladni pictures of tops that have been tapered. I'd guess that worrying about taper on guitar #3 is premature. I'm more worried that it doesn't look like it was made with an axe.

Later...just read this "As the torque falls off near the edges of the top less wood is needed, and the top can be tapered in thickness. This reduces the weight and frees up the main top mode. The bracing also can be tapered toward the edge to balance the top thickness and stiffness." from http://www.alcarruthluthier.com/Downloads/Acoustic1.pdf - I guess you all knew this anyway...




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