Fork temp (was C fork/A fork)

[Dave Nereson]

----- Original Message -----
From: Jason Kanter <jkanter@rollingball.com>
To: <pianotech@ptg.org>
Sent: Sunday, April 28, 2002 10:27 AM
Subject: Fork temp (was C fork/A fork)


> Tommy Black says:
> > I use C fork 523.3....always. I must be "right on" A440.
>
> You must be right on 440 if there is zero stretch in the piano (not on
this
> planet). The tuning fork sets  your "zero" point for stretch, and if that
> zero point is C, the A is going to be sharp.
>
> Not by much, though.
>
> Personally I think a bigger source of variation is the temperature of the
> tuning fork. I recently bought a C 523.25 fork, chunky aluminum type, and
> calibrated it using the Tunelab/NIST procedure that is so easy to do using
> Tunelab's instructions. I found that the difference between having the
fork
> in the toolbox on a cold day, vs. having it under my waistband for 5
> minutes, made a difference of just over 10 cents. There was easily a 50-60
> degree F temperature difference between those two readings. My waistband
> tends to be consistent within a degree, whereas the temperature of the
day,
> the car, the piano room all may vary a lot. This variation would cause far
> more deviation at A than would the degree of stretch.
>
> Spoken without measurements at hand, but someone must have measured the
> effect of temperature on a tuning fork. Ron?
>
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> jason kanter * piano tuning * piano teaching
> bellevue, wa * 425 562 4127 * cell 425 831 1561
> orcas island * 360 376 2799
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    I used to have one of those chunky aluminum C forks.  Used it for years,
then accidentally dropped it on concrete one day and it went quite flat.
The steel Deagan ones are more stable and less subject to variation.  If I
stick it in my waistband on cold days, it's warm by the time I have my tools
out, felts in, the SAT set up, wrist brace on, earplugs in, etc.  --David
Nereson, RPT, Denver