Re: [Harp-L] Fatigue and reed life

[Joe and Cass Leone <leone@xxxxxxxx>]

On Apr 17, 2008, at 7:16 PM, Aongus MacCana wrote:

> Hi Vern,
> I guess it would and as soon as you took any retuning cuts on the  
> reed you
> would undo any possible benefits.

Aongus, you have been right on the money all along. The idea is to  
not CUT. The tuning should be done by BUFFING. Anyone with half a  
brain knows that you never take sharp cuts to anything. Even the tiny  
parts of watches aren't cut sharply. ALL edges are 'broken'.  (eased  
or rounded off). Inside and outside edges are radiussed. Any Italian  
can tell you that not rounding is a big mistake with cement/concrete.  
Any boat builder can tell you that not rounding is a big mistake with  
fiberglass or carbon reinforced plastic resins.

> My instinct (like yours) is that work on the root of the reed, (in  
> other
> words tuning down) would be more detrimental because that is where the
> maximum bending moment and maximum stress would occur.

Absolutely, no question about it. I see the manufacturers 'step-down'  
the brass at the rivet pad. Sometimes it is very sharp. Big mistake.  
If I were making a long bow, I would never step down anywhere near  
the holding point (fulcrum), It has to be 'eased' down to spread the  
stress. That is why I voiced some concern the other day over SS  
reeds. My feeling was that they would almost HAVE to be thinner than  
brass in order to 'sing' with the pressure of the human breath. Maybe  
they have a way to soften the steel. But then, maybe there wouldn't  
have to BE a step down in the reeds profile. (or at least not as great).

> At the tip of the
> reed it would be relatively stress free.

Yeah, same as a tuning fork.

> Beannachtaí
> Aongus
>
> -----Original Message-----
> From: Vern Smith [mailto:jevern@xxxxxxx]
> Sent: 17 April 2008 22:33
> To: Aongus MacCana; Harp-L List
> Subject: Re: [Harp-L] Fatigue and reed life
>
>
> ----- Original Message -----
> From: "Aongus MacCana" <amaccana@xxxxxxxxxx>
> To: "Harp-L List" <harp-l@xxxxxxxxxx>
> Sent: Thursday, April 17, 2008 11:18 AM
> Subject: [Harp-L] Fatigue and reed life
>
>
> > ..................They also compress
> > the outer surface of such components by shot peening them  
> > (bombarding them
> > with steel shot)but this does not look like a feasible strategy for
> > harmonica reeds.
> > Aongus Mac Cana
>
> Bead-blasting, the same peening process but with very small glass  
> beads,
> might be feasible on reeds.  Tuning to lower pitch would spoil the  
> effect,
> if any.  Do you think that peening might alter pitch?
>
> Vern
> Visit my harmonica website www.Hands-Free-Chromatic.7p.com
>
>
>
>
>
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