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I want to try to make my own musicbox. The picture below shows what I mean: enter image description here

I was wondering how to determine the length of the metal tone generating plates (shown in dark grey). I assume it is a function of the length and thickness, I just don't know the exact relationship.

Could someone please provide me with a formula relating the plate dimensions with the frequency?

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I am not sure if this is the right SE to ask this, feel free to move it to a more suitable SE site. –  Bart Arondson Dec 4 '12 at 18:16

1 Answer 1

up vote 3 down vote accepted

The tuned teeth (or lamellae) of the steel comb is typically set to a chromatic scale. To change the tuning would require adding or subtracting material to an individual tooth with some trial and error and a good ear. Changing the length would cancel the action of the pins on the revolving cylinder so that is not a good idea.

If you think the scale you have meets your tuning definition then it would be far easier to make a new scroll to change to the melodic and harmonic content you desire. If you are starting from scratch and have the tools you should make a system to be able to change the scrolls so you have a diversity of songs.

Here is a reference to tuning the reeds on a harmonica since this is adding and subtracting material related:

http://www.angelfire.com/music/harmonica/mikesretuning.html

Information on how to tune lamellae as used in a Karimba:

http://www.nscottrobinson.com/mbiratunings.php

Here's a place where you can make your own music box tunes by using punchable paper strip musical movement:

http://www.deanorgans.co.uk/order_musicalmovements_mbm30hp.htm

Math part:

http://en.wikipedia.org/wiki/Tuning_fork#Calculation_of_frequency

UPDATE:

I am not entirely certain that using tuning fork math is the right place for a series of metal bars as found in a music box comb so I have done some more searches and found a reference that covers much more here:

http://windworld.com/features/tools-resources/exmis-free-bar-length-calculator/

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I was planning on doing it from scratch, I hadn't thought about changing the roll... I'll look into that, thanks. –  Bart Arondson Dec 4 '12 at 20:06
    
I would buy a cheap movement for like under $10 and experiment with it to gain experience before you start your design and first prototype. –  filzilla Dec 4 '12 at 22:39

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