# Help me help someone help someone else with their homework!February 12, 2014 6:20 AM   Subscribe

Can anyone direct me to a formula/table that will tell me what length to cut a metal pipe to make a chime with a predetermined pitch? They need to make a set of chimes.

These chimes will be mounted and struck like orchestra chimes (these aren't wind chimes). I seem to find formulas to determine frequency of the internal air column but that would be more appropriate to a flute. They need to build one diatonic octave (C to C) with an added Bb.

I know how I personally would build such a thing, but the teacher would like a more structured approach.
posted by sourwookie to Science & Nature (7 answers total) 3 users marked this as a favorite

Something like this?
posted by supercres at 6:28 AM on February 12, 2014

Sorry, just saw the specific note about not being wind chimes, but the formulas should be roughly the same, no?
posted by supercres at 6:32 AM on February 12, 2014

I would think so, as the "struck" mechanic is employed. That looks to be a great resource. I'll see if I can find it in there.
posted by sourwookie at 6:35 AM on February 12, 2014

How much information do you have about the pipe to start with? I feel like you would need to experimentally figure out where C would be, then you could use a formula (like the one in this article about hollow-tube chimes) to find the remaining lengths.
posted by mskyle at 6:35 AM on February 12, 2014

Experimental Musical Instruments Magazine's Free-Bar Length Calculator
posted by moonmilk at 6:38 AM on February 12, 2014 [2 favorites]

This page ought to give you everything you need to know, including the effect of end corrections. Just plug in the frequencies of the notes you want, and away you go. I don't think you need to get any more complicated than that.
posted by pipeski at 7:10 AM on February 12, 2014

This page ought to give you everything you need to know, including the effect of end corrections. Just plug in the frequencies of the notes you want, and away you go. I don't think you need to get any more complicated than that.

You do need to get more complicated than that, actually. The sound generated by an orchestral chime is not generated by a column of air inside vibrating; it's generated by the metal itself vibrating. This means that the frequencies of vibration are different, and in particular the frequencies aren't in the 1:2:3:4:… ratio that you would expect from an air column. The scaling of the tone with length is also different for a transversely vibrating bar than it is for an air column.

The standard reference for this is Rossing's Science of Percussion Instruments. I'm pressed for time right now, so I can't dig up an online resource explaining this, but if I manage to find one later I'll stop back in and post it.
posted by Johnny Assay at 7:31 AM on February 12, 2014 [2 favorites]

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