Compound Radius: Explained

Articulo de Stewmac:

On any fretboard, the tops of all the frets need to be aligned, either in a straight line or in a slight curve (called "relief"). Uneven fret heights are not acceptable, nor is too much curve, nor a reverse curve ("backbow"). All of these will cause playing problems. Any frets that sit above or below this ideal line will result in buzzing problems. Some fretboards are flat from side to side, and many more are radiused (rounded):
With a flat fretboard, the strings can run at any angle and always be at a consistent height above the fret tops.
A radiused board is uniformly curved its full length, as if it were the top of a cylinder. With a cylindrical fretboard surface, all the strings must be parallel to each other in order to keep a consistent height above the fret tops.
See what happens when a string is turned at an angle to the cylinder:
Typically, guitar strings are not parallel: they're closer together at the nut, and they spread wider apart at the bridge. For this reason, a fretboard should not be a cylinder. The strings would rise too far off the fretboard at some points. For comfortable playing, the fretboard needs to taper along with the strings, starting wide at the bridge and converging toward the nut.
When you combine this idea of converging strings with a radiused fretboard surface, you get a cone shape:
Straight lines (strings) following a cone's surface will not be parallel. They'll be tapered (converging to the point of the cone), the way we want our guitar strings to be. If they follow any other line, they'll create playing problems or string buzz too: We refer to these conical fretboards as "compound radius" fretboards.
Now that we see that the fretboard needs to be conical for lowest action, we can also see that the spread of the strings and the changing radius of the surface are interconnected. Once you determine the radius at the nut and the spread of the strings, the radius at the bridge is determined by those values. These photos show exaggerated radii, of course, to show the principle. A guitar string that's just a few thousandths of an inch too high or low will make a big difference in playing action and fret buzz.
How to determine a radius at any point on a fretboard
1. Using the spacing of the two E-strings at the nut and the 12th fret, extend the lines until they converge. Measure from the point of convergence to the nut and you will have "X" or the focal length. X is then used in the remaining formulas. X = Distance from the nut to the Origin (focal point) Rn = Fingerboard radius at the nut Rd = Fingerboard radius at "D" (a certain distance from nut) D = Arbitrary distance from the nut 2. The second formula assumes that you have already determined X, the location of the Origin of the cone. This solves for the radius at any point along the fingerboard represented by the value D. 3. The third formula, to find the point D where the radius equals a known value, is written as #3.

Neck Profiles: Fender Guitars

Un articulo de por ahi:

Fender Neck Profiles

As I stated in my article on Gibson neck profiles I think most guitar players look for a particular “feel” about the neck when trying to choose a guitar. Obviously that doesn’t just apply to Gibsons. In this article we’ll discuss Fender neck profiles, shapes, and variations.

Gibson guitar necks are generally categorized into two types, or profiles, with slight variations while Fender has had a long tradition of either three or five basic neck shapes depending on who you ask. I’ll try to address the discrepancy and let you decide for yourself.

The Basic 3

First: The “3” basic shapes as explained by Fender today and published on the Fender website. Fender defines “neck shape” and a “neck profile” as the “back shape” of the neck when cut into cross section as illustrated below. Neck width, neck depth, and fingerboard radius are not to be used to compound or complicate the basic neck shape/profile of Fender guitars.

“Fender uses variations of the “C“, “V“, and “U” designation for their necks. The illustration above shows from top to bottom “C“, “V“, and “U“.

C-shaped neck profile: The most common modern neck profile. C-shaped necks have an oval profile that works well for most playing styles.

V-shaped neck profile: Two versions are popular. A more rounded “soft” V and a more pointed “hard” V.

U-shaped neck profile: Chunky and rounded, with high shoulders. Some consider to be “baseball bat” necks.

There are also further subdivisions of each type, usually denoted by a design year or era (i.e., ’50s V shape, ’61 C shape, ’70s C shape), in which subtle period-specific variations in one of the basic neck profiles is recreated precisely.

There is occasional confusion about C, U and V neck profile designations and A, B, C and D neck width designations. From the early ’60s to the early ’70s, Fender referred specifically to the nut width of its instrument necks using the letters A (1 ½”), B (1 5/8″), C (1 ¾”) and D (1 7/8″). These letters were stamped on the butt-end of the necks and had nothing to do with neck profile.“

— Source: Jeff Owens, Fender Musical Instruments Corporation. Nov 20, 2009.

http://www.fender.com/news/fender-neck-profiles/

Read on for more …

Now let’s address the “5” basic shapes some use to describe Fender necks using the image below from fretboard.com.

The Basic 5

Some recognize the shapes “U”, “Soft V”, “Oval”, “Hard V”, and “Flat Oval” as the 5 basic Fender neck shapes/profiles choosing to not designate a “C” shape/profile. While this is contraindicated by Fender in the article citation earlier in this article it is an interesting point. That point was addressed earlier in the Fender citation:

“There is occasional confusion about C, U and V neck profile designations and A, B, C and D neck width designations. From the early ’60s to the early ’70s, Fender referred specifically to the nut width of its instrument necks using the letters A (1 ½”), B (1 5/8″), C (1 ¾”) and D (1 7/8″). These letters were stamped on the butt-end of the necks and had nothing to do with neck profile.”

— Source: Jeff Owens, Fender Musical Instruments Corporation. Nov 20, 2009.

http://www.fender.com/news/fender-neck-profiles/

Fretboard.com once published:

Here are the basic neck shapes Fender uses:

• No. 1 – Essentially a round, chunky, ’53 Tele shape – the “U” shape, with lots of shoulder
• No. 2 – Also called the “54” or “soft V”; it has some shoulder, but less than No. 1
• No. 3 – The 1960 and ’62 “oval” shape; thinner, front to back, at the 1st fret than at the 12th
• No. 4 – Different from the large, soft No. 2, this is a “hard V” that’s .030″ thinner front to back, generally found on Strats from ’56 and ’57
• No. 5 – The contemporary “heavy metal” style neck; similar to the ’80s neck on Jackson, Charvel, Ibanez and other models; much flatter
• No. 1056 – Patterned from a 10-56 neck (10 = October, 56 = 1956), it’s a very big V neck. You could call this a good example of the ‘boatneck’

Any one of these patterns can be altered slightly to differentiate between one model guitar and another.

As to fret board radius dimensions, the vintage radius for early Strats and Teles was 7¼”. These days the typical radius is 9½”, which is nice for Blues bending and is used on the Eric Clapton model. There are a few differences, though. The SRV and Eric Johnson models have a 12″ radius, which makes for easier bends and less fretting out of the strings.

—- Source: Fretboard.com

http://www.fretboard.com/fenderneckclarity.html

Further confusing the issue with Fender neck shapes/profiles I ran across a number of images I’ve found that I’ll share with you here:

The 6 shapes:

The 7 Shapes:

The Granddaddy of Fender Neck Shapes/Profiles:

Conclusion:

As you can see Fender neck shapes/profiles are all over the map with slight variations due to year of manufacture, physical shape, and heavily dependent on variations to command a specific “named shape”. As usual there is no right or wrong and I imagine there are plenty more out there that I may not have covered here.

Neck Carving / Fretboard Radius Jig

Encontré este Jig para hacer formas bastante exactas y controladas para el brazo de cualquier instrumento. Es fácilmente modificable y se me ocurre que con solo cambiar un par de cosas o 3 se puede usar también para hacer radios compuestos (o no compuestos) en el diapasón.

Conversión a resonador - Parte 5

Hace ya varios meses que di por terminada esta guitarra, por lo menos la fase un poco mas seria de construcción. Esta parte en especial fue sobre todo de ensamblaje. El mismo día que llegaron las partes que estaba esperando pude tocarla y oír como sonaba la invención. Como ya estaba todo bastante listo fue de montar el cono con el puente, hacer mediciones y ajustar la altura de las cuerdas en el puente junto con el radio. Después fue de hacer los ajustes para que entraran los cobertores de las bocas de la guitarra y terminar montando la tapa del resonador y así fue como quedo:

En la cabeza también estuve trabajando. Rebaje uno de los lados para que fuera mas fácil doblarla y coincidiera mejor con la forma. Hice un par de pruebas de como encolarla y luego con varios sargentos y cuerda la deje que la cola se secara toda la noche.

Acá la parte entretenida fue volver a hacer los canales del clavijero. Lija, formón, y mas lija... Un poco disparejos, yo se, pero así fue como quedo:

Estoy pensando en cambiarle las clavijas por otras que compre nuevas pero no calzan, así que tendría que rellenar los huequitos y volverlos a hacer. También falta la parte del acabado. Paciencia.....

Primeras guitarras - Planeacion

He decidido, después de un arrebato de creatividad/locura empezar a construir 3 guitarras eléctricas sin mucho mas que las herramientas que tengo y algunas que iré comprando de camino. No se como saldrán al final ni cuanto tardare pero ahí voy.

Porque 3? Fácil. Compre un tablón de pino de 2" x 8" x 3.20m que me alcanzo para 3 cuerpos. Porque pino? Por dos razones: 1. desde hace ya un buen tiempo vengo viendo las telecaster de pino de Stewmac y me gustan un montón, y 2. se me hace muy fácil de conseguir, es barato, viene en buenas dimensiones y seco, perfecto para empezar a jugar de luthier.

Entonces, las 3 guitarras son: una tipo telecaster de pino con nudos, un bajo de 6 cuerdas sin trastes y otra que no estoy seguro todavía. Entre las opciones para esta 3era están una stratocaster, una explorer, una SG o alguna otra cosa que se me ocurra de camino.

Para la telecaster tengo una estética bastante definida. La idea es que se vean bien los nudos y las vetas. El acabado va a ser en aceite, Tung oil, tru-oil, aceite linaza o algo parecido, que se aplique fácil, sin pistola, ni mucho lijado ni nada muy complicado. Esta foto se acerca bastante a lo que ando buscando.

El bajo, como ya dije, va a ser de 6 cuerdas. Inicialmente pensé en un jazz bass de 4 cuerdas pero ya tenia unas pastillas y un peamp que había comprado hace unos a;os para 6 cuerdas y nunca use entonces van a ir en este. Siempre me han gustado los singlecut así que este va a ser singlecut. la madera del cuerpo no es muy llamativa que digamos entonces pensaba pintarlo de negro y el brazo de arce pintarlo transparente.

La 3era guitarra no la he pensado demasiado. Inicialmente iba a ser una Strat, pero últimamente no estoy tan seguro. La telecaster va a llevar pastillas de strat entonces seria como tener, en cuanto a sonido, dos guitarras iguales y por eso estaba yéndome mas por una con humbuckers, de ahí lo de la SG o explorer. Me gustaría una Les paul pero no tengo las herramientas para hacer la tapa arqueada y no se que tan confiables sean mis habilidades para hacer un encastre "set neck". Por otro lado me gustaría que fuera escala 27", en plan barítona. Vamos a ver en que termina todo este asunto.

Las 3 las estoy haciendo como si fueran para mi, no estoy pensando en venderlas por ahora, aunque si sale comprador es probable que las venda. La idea sobre todo es aprender, desarrollar habilidades, y sacarme las ganas de hacer yo mis propios instrumentos.

El proceso ya lo empece hace unas 3 semanas y tengo unas cosas ya hechas. Poco a poco en posts separados por instrumento iré subiendo las fotos y explicando un poco los métodos, las desgracias y lo que ha ido aprendiendo.