Musical Metal

[Quick Change]

I built a wooden music machine run by finger power a few years ago. The drum and pins, gears, crank, flywheel are all wood. The only metal on it is lengths of bronze tubing tuned to a pentatonic scale. These don't sound as good as they could but are better than regular copper tubing. Does anyone out there know what to look for in the way of metals used for their "musical" properties. Most past advice I've received has been just to get the hardest alloy possible, but this principle alone doesn't always make for good music. Quality of the sound has a lot to do with the overtones generated at a given pitch. After all, regular old steel drums make pretty decent caribbean music when crafted the right way. I can find no books on the subject.

What kinds of alloys are used in ships bells? church bells? glockenspiels? xylophones?, wind chimes? tuning forks?

Is tubing better than solid? What ratio of wall thickness to length is best?

What grade of metal do I ask a supplier for?

Any tricks about forming or heating the metal?

[Al Messer]

Bells are usually case of Bronze Alloy, but I haven't the slighest idea as to the alloy composition.

[Oso]

Well, for resonance, you want a material with low energy loss when vibrating.

That does usually mean hardness, as the hardness imparts a springy rigidity as opposed to a lead-like dullness. Then the energy is lost mainly from moving air and making sound.

I have seen aluminum (hard alloys), bronzes, brasses, steel, etc used in wind chimes, even hard drawn copper tubing.

The steel drums you mention have a pitch, but don't have much sustain. They lose energy very fast and tend to make a short "boink" noise on pitch, not a longer "boinnnnnggggg".

Circular forms work best, as they have fewer vibrational modes. Cow bells are square, don't make as pure a tone, and they also lose energy fast.
Bells are round, and have fewer non-harmonic overtones.

Thicker walls damp overtones faster, leaving purer tones. Too thick don't really vibrate at all, though. It will depend on the metal.

Look up "bell-metal" and I bet you find a range of alloys.

Striking clock bells are often made of straight round bars, or thick spiral coil springs. I have clocks with both.

[This message has been edited by Oso (edited 09-07-2002).]

[Uncle Dunc]

I saw an interesting bell at a gun show one time. It was ugly, but I thought it had a nice tone and a good sustain. It was made from the top third of an oxygen cylinder. Ever since then I've been trying to figure out how to adapt a grandfather clock movement to use a bell like that for its chimes.

[Thrud]

Quick Change:

Like Oso I have seen many wind chimes with aluminum tubing. Triangles are solid steel or brass and resonate like they do partially because of how they are hung. A Tubular bell (Triangles made from tubing) have exquisite tones - Mike Oldfield has four albums out with these instruments - Tubular Bells, Tubular Bells 2 & 3, and Orchestral Tubular Bells. In the first album he goes through the twenty or so different instruments he played on the track at the end - sold me forever on them. Sounds gorgeous on my electrostic panels.

I seen a show the other day that had a gentleman that was a master glass blower - they build ($20K each) a reconstructed "glass harmonium" invented by Ben Franklin. I guess even glass could be used - experiment with different materials. Generally anything that is light will vibrate well - reeds, drum skins. Surface hardness will also have bearing on the tones. Also very hard wood is used in xylophones and their ilk.

You have some fun experimenting to do - get the kids to help (they like making noise)!

[SGW]

I assume you'd want seamless (as opposed to welded) tubing. If you look inside the tubing, welded will have a slight ridge running down the length of it.

There is a "bell brass" alloy, I think, but how you'd go about getting tubing made of it I have no idea.

As far as aluminum tubing is concerned, you might try calling Kaiser Aluminum or Alcoa or such, getting one of their "application specialists," and asking them. The information you seek must be known, somewhere, but it may be hard to dig up.

[Quick Change]

Uncle Dunc,
Next time your traveling along the rugged coast of California's Highway 1, stop at Nepenthe. It's a restaurant / art store on the Big Sur coast that has a bunch of welding tank chimes hung in various artsy type frameworks. The were pretty high priced, but this area caters to the carriage trade.

Thrud,
I also saw a show on the Ben Frankiln harmonium. Also saw another show years ago about a company that made modern church "bells". The unit consisted of carefully crafted hard glass tubes which were struck and amplified electronically. The output was then fed to speakers in the church tower. It sounded just like a Euoropean cathedral but the "bells" existed in a unit about the size of a stereo receiver. Much less maintenance and easier to operate for the churches.

[Rich Carlstedt]

Bell Metal is a closly guarded secret it seems. Guess the foundries keep it close to the vest. Did some research a few years back for a friend of mine and the only formula I could come up with was 75% Copper and 25% Tin Alloy. I assume that if a foundry found out that adding a small amount of other elements helped, they kept it close to the vest and didn't tell.

[Rich Carlstedt]

Forgot to mention..Shape is important to any vibrating body. The waves of enegy must keep moving within the body to keep it resonateing.
Think of a swimming pool (square)
If you start a huge wave , in will bounce back and forth between the opposing parallel walls ...for quite a long time (resonation)but the same thing in a triangular pool will cancel itself out quickly

[Uncle Dunc]

>> Bell Metal is a closly guarded secret it seems.

Guarding the composition of an alloy that is used to make many thousands of more or less easily accessible artifacts would be a pretty good trick.

A Google search turned up quite a few references. I stopped looking after six or seven. Most of them say 80% copper and 20% tin. One said the tin content ranged between 20% and 24%. One said 13 parts copper to 4 parts tin. One source specifically said there were no other elements intentionally in the alloy, just pure copper and tin. (There would obviously be traces of other elements.)

This site http://www.hibberts.co.uk/meneely.htm says, "The development of the alloy was concluded many years ago. Some of the oldest bells that we have records of were made from a mixture of copper and tin such as is used today. And in spite of certain statements that one hears as to the use of silver, the 'bell metal' that is defined in texts is a definite alloy that is used by practically all the modern founders." Another source specified that "many years ago" means more than 300 years.


[This message has been edited by Uncle Dunc (edited 09-07-2002).]