Reeds: Length vs Internal Volume

[PJ]

What is the relationship between length and internal volume? For instance, if length is constant, but internal volume is reduced, will this give a sharper or flatter pitch?

I've made a batch of reeds which are all sharp (5 to 10 cents). Would it help if I used a sanding block of a larger diameter (eg. 2 inches instead of 1 5/8). This would give a smaller "dip" in the slip and so the internal volume would be reduced. Should this produce a flatter reed?

[AlanB]

The most efficient way to enlarge the volume of the reed, is to alter the cavity above the staple eye. Do this by having a wider shoulder area (or shorter tail, depending which way you look at it), or by introducing a cavity in the slip above the eye. This is akin to the '2nd gouge' that is often used, but, if you run the 2nd gouge to the tail, it has less of a pronounced effect, so you really want the cavity to exist above the staple eye. I suppose a wider head has some flattening effect, but I think introducing cavities in to the reed has a less erratic effect on tuning, though it is said that the cavity/gouge can alter/improve the relationship between your E's.....

I'd do the cavity by using a one size smaller gouge than initially used (i.e do slip with #4, do gouge with number 3), just run the gouge in to the slip where you want to start (say 15mm from lips, run it down 5mm), then reverse slip and do the same to lift out the piece od pith you want removed. Guess you can smooth it with a little sandpaper on your finger?

This way you don't have to radically alter your staple volume to achieve the same....

[PJ]

Thanks Alan. I've been adding a tone chamber to the reeds, trying to increase the internal volume, but I was removing the pith to the end of the tails. I'll try what you suggest.

[AlanB]

Hope it helps... And apologies, that should have read 'run it down 15mm' not 5mm.... though it never harms to mix it a bit, I guess you can achieve a result with the small numbers. Maybe just gouge a bit deeper if you do? ...