Metal working question

Hello all,

Through a friend I have access to a metal working shop that mostly deals
with aluminum - especially chunks of it. While I do have Cris Foster's
Musical Mathematics I have been scouring the internet without success so
far for guidance on shaping metal to produce interesting sounds. The
closest I get is the manufacture of cymbals and gongs which yields some
great information though I'm thinking not too applicable working in
aluminum. Does anyone know of a resource beyond what I have access to
already?

Thanks for your time,

Chris

--- In tuning@yahoogroups.com, Chris Vaisvil <chrisvaisvil@...> wrote:
>
> Hello all,
>
>
> Through a friend I have access to a metal working shop that mostly deals
> with aluminum - especially chunks of it. While I do have Cris Foster's
> Musical Mathematics I have been scouring the internet without success so
> far for guidance on shaping metal to produce interesting sounds. The
> closest I get is the manufacture of cymbals and gongs which yields some
> great information though I'm thinking not too applicable working in
> aluminum. Does anyone know of a resource beyond what I have access to
> already?

Chris, talk to me. I've become an expert in the theory and practice of carving marimba keys, and also I've been helping Daniel Schmidt make American-style gamelan keys out of aluminum. With just a mill and a band saw you can completely control several of the lowest-frequency relevant modes of the spectrum (which is basically four modes - the fundamental, two overtones, and the first lateral mode). If you want to make other wacky shapes besides rectangular bars I can help you tune their modes as well.

I wouldn't recommend reading a book with lots of math if all you want to do is tune the modes. The math is beautiful and nice to understand, but pretty irrelevant for actually making keys. When you make a key you don't spend a bunch of time doing calculations (which would be hopelessly inaccurate anyway unless you're using sophisticated software); instead you spend the time measuring the frequencies of the different modes and then removing material in a feedback process.

Here's the best description I've found of the modes of a key that are relevant to its sound, and how to tune them: http://www.lafavre.us/tuning-marimba.htm It's written with wooden keys in mind, but it applies equally well to aluminum. The different stiffness and density will change the absolute frequencies for a given shape and size of key, but the mode shapes and how to tune them are no different.

Keenan

Hi Keenan - that is a very interesting reference.

Let me post pictures tomorrow of my DOA piece of aluminum and see if it can
be saved.

Chris

On Tue, Aug 21, 2012 at 7:32 PM, Keenan Pepper <keenanpepper@...>wrote:

> **
>
>
> --- In tuning@yahoogroups.com, Chris Vaisvil <chrisvaisvil@...> wrote:
> >
> > Hello all,
> >
> >
> > Through a friend I have access to a metal working shop that mostly deals
> > with aluminum - especially chunks of it. While I do have Cris Foster's
> > Musical Mathematics I have been scouring the internet without success so
> > far for guidance on shaping metal to produce interesting sounds. The
> > closest I get is the manufacture of cymbals and gongs which yields some
> > great information though I'm thinking not too applicable working in
> > aluminum. Does anyone know of a resource beyond what I have access to
> > already?
>
> Chris, talk to me. I've become an expert in the theory and practice of
> carving marimba keys, and also I've been helping Daniel Schmidt make
> American-style gamelan keys out of aluminum. With just a mill and a band
> saw you can completely control several of the lowest-frequency relevant
> modes of the spectrum (which is basically four modes - the fundamental, two
> overtones, and the first lateral mode). If you want to make other wacky
> shapes besides rectangular bars I can help you tune their modes as well.
>
> I wouldn't recommend reading a book with lots of math if all you want to
> do is tune the modes. The math is beautiful and nice to understand, but
> pretty irrelevant for actually making keys. When you make a key you don't
> spend a bunch of time doing calculations (which would be hopelessly
> inaccurate anyway unless you're using sophisticated software); instead you
> spend the time measuring the frequencies of the different modes and then
> removing material in a feedback process.
>
> Here's the best description I've found of the modes of a key that are
> relevant to its sound, and how to tune them:
> http://www.lafavre.us/tuning-marimba.htm It's written with wooden keys in
> mind, but it applies equally well to aluminum. The different stiffness and
> density will change the absolute frequencies for a given shape and size of
> key, but the mode shapes and how to tune them are no different.
>
> Keenan
>
>
>

It sounds to me like you want a computer program, not a book. Something that can do lots of calculations of sound bouncing around in different shapes. I don't really know what the best software for that is, though.

Andrew

--- In tuning@yahoogroups.com, Chris Vaisvil <chrisvaisvil@...> wrote:
>
> Hello all,
>
>
> Through a friend I have access to a metal working shop that mostly deals
> with aluminum - especially chunks of it. While I do have Cris Foster's
> Musical Mathematics I have been scouring the internet without success so
> far for guidance on shaping metal to produce interesting sounds. The
> closest I get is the manufacture of cymbals and gongs which yields some
> great information though I'm thinking not too applicable working in
> aluminum. Does anyone know of a resource beyond what I have access to
> already?
>
> Thanks for your time,
>
> Chris
>

--- In tuning@yahoogroups.com, "bigAndrewM" <bigandrewm@...> wrote:
>
> It sounds to me like you want a computer program, not a book. Something that can do lots of calculations of sound bouncing around in different shapes. I don't really know what the best software for that is, though.

I know COMSOL works really well for this - the only problem is it costs many thousands of dollars. There is free finite element analysis software (I've heard of Elmer and FreeFEM), but I haven't tried it out yet. See http://en.wikipedia.org/wiki/List_of_finite_element_software_packages

Keenan