Re: [Harp-L] Re: Harp-L Digest, Vol 133, Issue 22

[Vern <jevern@xxxxxxx>]

Your reasoning is correct all the way down to your conclusion which is not:
Colder metal is stiffer.  Correct but you may have over-estimated the magnitude of the effect.
Stiffness resists movement. Correct.  Increasing the thickness of a reed near the rivet has the same effect.
However, a stiffer reed (e.g. thicker near the rivet) has a higher pitch.

Vern

On Sep 23, 2014, at 4:02 AM, Larry Sandy <slyou65@xxxxxxxxx> wrote:

> 
> Interesting Vern. Thanks for that good information. I had reasoned the colder metal got, the stiffer it became, thus more resistance to movement ( which I thought would lower its pitch). Kinda like truck springs in sub zero temps feel stiffer than in summer heat. 
> I think it was Richard Sleigh who explained to warm up the reeds while tuning so moisture build up on cold reeds doesn't influence the accuracy of the pitch. 
> I am feeling lower pitched these chilly early mornings. LOL
> 
> Lockjaw Larry
> 
> From: Vern <jevern@xxxxxxx>; 
> To: Larry Sandy <slyou65@xxxxxxxxx>; 
> Cc: patpowers@xxxxxxx <patpowers@xxxxxxx>; harp-l@xxxxxxxxxx <harp-l@xxxxxxxxxx>; 
> Subject: Re: [Harp-L] Re: Harp-L Digest, Vol 133, Issue 22 
> Sent: Tue, Sep 23, 2014 9:18:33 AM 
> 
> If you cooled a brass reed by 20 degF, its pitch would INCREASE by about 1 centâ.imperceptible among the other variables affecting pitch.  (derived from the chart at http://www.engineeringtoolbox.com/young-modulus-d_773.html ) Note that E (modulus of elasticity) decreases with increasing temperature and that pitch is proportional to the square root of E.  
> 
> If the pitch is decreased by moisture on the reed, the effects would tend to cancel.
> 
> Vern
> 
> On Sep 22, 2014, at 5:36 PM, Larry Sandy <slyou65@xxxxxxxxx> wrote:
> 
> > Pat, that's interesting.  I have never heard that cold reeds are less flexible. That must translate into them playing a LITTLE FLAT until they warm up. I know cold reeds collect breath moisture quickly though, which would also lower the pitch. Interesting parallel.  I wonder if cold, moist reeds are double flat?  ð<br/><br/>Lockjaw Larry
> 
>