Cane springyness revisited

[rorybbellows]

As you are all aware, I invented a method to determine cane springyness that is now used by millions of reedmakers around the world. But after making and testing many reeds of different springyness ,I am now in two minds if cane springyness is that important.
First of all what is the point of establishing a desired amount of spring if as soon as you tie up the reed and start the scrape and that spring is changed by removing cane with the knife.
Secondly if different cane springyness equals different cane thickness,then when the reed is scraped the difference is compensated for by adjusting the scrape.Thicker cane would mean you take a bit more off the scrape and with thinner cane less would be removed.

Good reeds are made or ruined by the scrape. Would you agree?

RORY

[billh]

What you say is true to a point. However it ignores the important issue of tail springiness, for one.

OK, then assuming that the tail springiness needs to be dealt with separately (and that's a topic in itself); the blade springiness can partly be compensated for with the scrape. But the scrape doesn't cover the whole reed head, and if the blades are overly stiff, the scrape will have to be extremely U-shaped in order to compensate - leaving the sides of the reed still very rigid. In this last scenario there is a tendance to produce reeds that close in the center first, in a figure-of-8 shape, which is bad.

Conversely, a reed that is too soft before scraping may lack sufficient stiffness on the sides, leading to other problems even if the lips are left thick - the lips will have too much mass and it may be hard to keep the crow pitch high enough.

At least that's my understanding of why the scrape can't always produce a working reed even if the geometry looks right and the gouging was done carefully (but without regard for stiffness issues).

Bill

[patsky]

Rory,
What is the "Scientific Test" ?


Pat Sky

[Buckeye]

Pat,

I believe he was refering to this thread a few months back but now the photos are gone.


viewtopic.php?f=6&t=63580&hilit=springyness


Sean

[rorybbellows]

I’m sorry, but on advice of the copyright office and my solicitor I had to take those photo’s down.
But here’s the jumping elephant instead.



Getting back to the topic, has any research been done on how much of the reed actually vibrates when the reed is working ? Some home trails can be done by sucking on a reed while lightly touching the scrape with your finger you can easily feel the scrape vibrating and it doesn’t take much pressure on the scrape to completely dampen the sound. If you then while sucking the reed touch the sides of the reed you can only feel some slight vibrations and in the area below the scrape and above the binding there are no vibrations felt at all. Does this mean that these area’s are not vibrating ? If you think of the part of the reed head that is not the scrape, it could be described as a kind of frame that is holding the scraped cane and as it is with all vibrating membranes if the frame holding them is firm and stable they vibrate better.
I think I have found this to be the case in a reed I made from a very thin slip which would result in a “weak frame”, the tone of the reed was weak and very low in volume, where a reed made with a thicker slip with a “strong frame” sounded very strong and lively .

This puts the whole idea of tail springyness in to question.

RORY

[billh]

Tail springiness is important not because of vibration directly, but because of the effect on the reed geometry.

You can feel the vibrations more near the edges because the amplitude is greater; that doesn't make the smaller amplitude parts unimportant. Consider a simple clamped bar: near the clamping point the motions are smaller, but adding rigidity there still has a strong effect on the overall motion (frequency and amplitude).