On Dec 4, 2010, at 3:29 PM, d. sacchrone wrote:
> Odds-
> I have an upcoming piece for balinese gangsa, and have just learned the instrument is no longer available. I am thinking of using copper tubing as a rough replacement.
and
On Dec 5, 2010, at 9:45 AM, RP Collier wrote:
> On Dec 4, 2010, at 3:29 PM, d. sacchrone wrote:
>
> > Most bar length calculators require a cut and tuned a sample bar
> > which I do not have. Any ideas or input?
>
> I think Greg B would be able to help with this.
i've just discovered that, to my surprise and alarm, my spam-catching service had blocked this entire discussion! i've just been through over 2000 emails, and discovered a few more false positives. it's hard to imaging that there are that many evil spammers attempting to sell illicit metallophone tuning solutions, but there it is.
it may be too late for useful comments, but here are a few anyway:
in my experience, copper tubing is a very poor idiophonic material, either pure or in the alloys used in commercial plumbing. in short, it goes clank more than ding, which is to say, it blows its energy budget on a large number of non-harmonic overtones while producing little or no clear fundamental. the problems with high-copper alloys is made worse by the relatively thin walls of hardware store copper pipe.
various bronze alloys (i.e. copper and tin, plus the odd bits of iron, nickel, etc.) seem to be the most successful alloys for bells and gongs. but bronze is relatively hard to find in your local hardware store, and can be difficult to work.
Banek & Scoville and -- as BobC pointed out -- Bart Hopkin recommend steel as being the best balance of cheap and easy (to find and work, that is). See Bart's brilliant "Making Simple Musical Instruments" -- a photo-filled companion to his more encyclopedic and just as brilliant "Musical Instrument Design -- which is out of print but available used on Amazon. And of course his more recent "Making Marimbas and Other Bar Percussion Instruments" and "Wind Chimes: Design and Construction" are available from his site:
http://windworld.com/products-page/books--cds/
Bart details the use of 3/4" EMT -- steel Electrical Metal Tubing, or steel conduit, which is available at most DYI/hardware stores. i've made a large number of bars out of this stuff. that's 3/4 inch internal diameter, usually in 20 foot lengths. it has a rough silvery surface -- Bart recommends avoiding pieces with heavy seams or overly-smooth finishes.
as BobC says, Bart recommends cutting the tubes a bit long with a hacksaw and then grinding down to the desired pitch. a grinding wheel is probably the right tool for the job here, but i use a belt sander with 80 grit paper. be warned, this produces a LOT of sparks that fly a surprising distance, and it makes a odd-and-LOUD-music while doing so. and it produces metal shavings and "sawdust". wear safety glasses and not-your-favorite shirt, and watch out for flammable items in the spark path. i prepare carefully, and then laugh maniacally while tuning these things. note: a spot of oil helps a lot with the hacksawing. and those rare earth magnets in woodworking and craft stores help clean up some of the resulting mess.
Bart gives some rough starting pitches -- these will be a bit flat, to allow tuning via grinding. I'll copy a few in here, but for goodness sake, buy Bart's books for the full scoop.
C5 -- 14-7/16"
A4 -- 15-3/4"
E4 -- 18-5/16"
all of the books mentioned discuss schemes for tuning overtones and resonances., e.g. wedging in foam as BobC mentions, drilling holes in the tubes, squishing the tubes, etc. as does this article:
http://windworld.com/features/tools-resources/making-self-resonating-chimes/
self-adhesive foam weather stripping stuck on 22% of the way from each end makes an easy, effective mount. and i've used little chunks of the same weatherstripping to kill unwanted tones and provide a bit of damping -- this may be a quick way to roughly match the timbre of the other metallophone bars.
Bart has also discussed making tuned aluminum gongs by hammering a boss. i have not (yet!) played with this approach, but i hope to at some point.
and don't forget the free bar calculator on the ExMI site:
http://windworld.com/features/tools-resources/exmis-free-bar-length-calculator/
and here's a new note on an even simpler mounting option:
http://windworld.com/tools-techniques-ideas/another-way-of-mounting-free-bars-and-other-percussion-objects/
-g
-- www.gregorynormanbossert.com --
-- www.suddensound.com --
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