Re: [Harp-L] Life of narrow reeds.

[Vern <jevern@xxxxxxx>]

Theoretically, the stresses in a reed are not a function of width.  Thus the stresses in a narrow reed should be no more than those in a wider one.

Do the following mental experiment:

Imagine two identical side-by-side reeds vibrating at the same frequency, phase, and amplitude.  Viewed from the side, they would appear to be one reed. Then join them into one reed of twice the width. There are no forces between the halves either before or after they are joined.  This is why you can trim a reed to a narrower width without major changes in pitch.

Has Hohner changed the design of the reeds in other ways beside just making them narrower?  If this is the source of the problem, then your trimmed reeds should live as long as the older wide reeds.

It is possible that some secondary effect accounts for the observed shorter life of narrower reeds.  However, it is not predicted by the formulas for bending stress. The expression for metal stress in a reed does not include a width variable.

I can speculate about why they made the change.  They thought that the smaller orifice for air flow would make it easier to form a resonant embouchure and make the high notes easier to play.  Maybe Rick would know.

Whatever the reasons, they created a major problem for reed-replacing technicians.

Vern
  
On Nov 12, 2013, at 1:52 PM, diachrome@xxxxxxxxxxx wrote:

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> ----- Original Message -----
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> Message: 2 
> Date: Tue, 12 Nov 2013 08:32:29 -0800 (PST) 
> From: Winslow Yerxa <winslowyerxa@xxxxxxxxx> 
> Subject: Fw: [Harp-L] Polishing reeds 
> To: "harp-l@xxxxxxxxxx" <harp-l@xxxxxxxxxx> 
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> Mike -ï 
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> Any comment on the longevity of Hohner chromatic high reeds since the reed redesign circa 2005? 
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> Winslow 
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> <<Yes, Winslow. The problem occurs with all the X series plates including those prior to 2005. I don't know what Hohner was thinking when they narrowed almost half the reeds on their chromatics. 
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> Where the older model 270's and CX-12's seem to fatigue most is on holes 6 and 7. The newer reeds fail most on holes 6 to 12. The Tenor models seem to be the worse. They constantly fail for my customers on holes 9 to 12. 
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> I don't think it is the reed material because when it comes time to replace the narrow reeds I have to trim either newer reeds I've purchased from Hohner or use the NOS reeds I have. AFAIK HohnerUSA doesn't sell the narrow reeds. 
> The reeds I trim fail just as fast as the ones Hohner installs. 
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> I do think that while narrowing the reeds may make them respond with a little less effort the trade off are expensive repair bills over the life of the harmonica. I really wish they wouldn't have tried to fix something that wasn't broken. I strongly believe they should go back to the wider reeds>> 
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> ----- Forwarded Message ----- 
> From: "diachrome@xxxxxxxxxxx" <diachrome@xxxxxxxxxxx> 
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> I don't think or try to do anything special to the reed other then install it correctly and they generally last many years. The exception being on the upper narrower reeds on Hohner chromatics. 
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> Mike 
> www.harmonicarepair.com 
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