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Folks, I'm a bit stumped over this one. For a while now I've been making "cylinder top" guitars, based on the old Howe Orme design. But the tops are a bit more complex than a plain old cylinder. On the outside, they're flat, and in the middle they're curved. On top of all this the central cylinder section is tapered, the radius is larger at the tail end that the neck.

Those of you with a mathematical or engineering background - do any of you know what this type of shape might be called?

Here's an image of the tail.

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nigel

http://www.theluthierblog.com

How about edge flared conical?

The instruments I build with what I call "cylindrical tops" actually use more of a spline curve, but they don't have the recurve on the edges that your's is showing. "Cylinder top" probably came about because it was easy to say once people knew what you were talking about. Easier than say... variably recurved spline cross sectioned top....

Hey Nigel, we wouldn't want you getting all mathematical on us! .

How about The Manta Ray top?

(Otherwise something like a compound tapered reverse hyperbolic paraboloid)

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Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

http://www.goreguitars.com.au

Ha! Yes Trevor, you've had a terrible influence on me this last year. I've invested in an abacus.

One chap I talked to used the term "faircurve" which I believe is a boat building term for one shape blending smoothly into another. That seems ok, but not specific enough. "Compound tapered reverse hyperbolic parabaloid" it is then!

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nigel

http://www.theluthierblog.com

I always find your builds have an nice aesthetic touch to them Nigel.
You should post more pictures.
May I ask, do you find an advantage of some kind in a build like this, over domed tops and backs?

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

Normal probability distribution top.


Sent from my iPhone using Tapatalk

Looks like a cycloid.
http://www.cgl.uwaterloo.ca/~smann/ccycloid/

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Dave
Milton, ON

That's nice to know. Yes, I think it's a great way to build. Very logical. I'm in the process of putting a new ebook together about the design, that's when it occurred to me that "cylinder top" doesn't really cover it.

This is one of the first ones I made:

http://youtu.be/YN16lL5lDE4

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nigel

http://www.theluthierblog.com

I like manta ray, it is descriptive of the shape. Beautiful shape it is too. T

That's cool. I've never seen anything like that. I vote for manta ray!

Being from Tampa, I like the manta ray name (Rays is the name of our baseball team), but I think Dave is right. After downloading the file that Dave pointed to, I agree, it looks like a cycloid. Nigel, enjoyed your utube video, and like the shape of your top; it's very pleasing to the eye as well as to the ear.

A lump?

My first thought was "recurved lateral arch top", but since the method of construction is so different than a carved arch top, which is probably what most people would think of when hearing that, maybe just "lateral recurve top"? Unless it sounds more like a carved arch top than a flat top, and then maybe the association would be a good thing.


Bell curve did come to mind. But then you get ambiguity with the church bell type shape, being music related...

Certainly is a cool shape

call it the "Forster Curve", take out a patent, and the money will roll right in.

Interesting, I concur with Manta Ray.

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久保
美智え

Sloped serpentine?

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wah
Wah-wah-wah-wah
Wah

Stealth Bomber? Or to be more specific, SR-71.

Pat

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formerly known around here as burbank
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http://www.patfosterguitars.com

Puckered butt?

Think the term you are looking for is parabolic.

If it tappers back down in the middle (saddle like shape) you can go with hyperbolic paraboloid! which face it is just plain nerd cool.

Nate

Complicated?

Compound-round?

Alex

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"Indecision is the key to flexibility" .... Bumper sticker

You know, like the carve on a LP top.

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wah
Wah-wah-wah-wah
Wah

Well, it kind of looks like Robin Hood's bow to me and being that Nigel is from England maybe he can call it that or a Sherwood Curve or sumthin like that?

Nigel,
Whatever you choose to call it, your detail shot shows beautiful craftsmanship as far as I can see, and I salute you on the accomplishment. You've stated that you've built a few of these "cylindrical" tops and it appears to me that you have all of the geometry mastered. Now...as to a name..... Hmmmmm..... I can't help you in a serious way that respects your question. I am not a mathematician. When I'm stuck in a situation like this and someone asks me what I call such a thing, I say: "Phyllis", because I can't think of a better answer.
Having admitted that to my own embarrassment, I will add that I think "Manta Ray" is perfect. Repeat it and post the results often enough, and pretty soon other people who emulate the shape will be referring to it as the "manta ray".
Soon after, I expect a fair number of people will be trying to make one similar to it.
Patrick