----- 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? > > || ||| || ||| || ||| || ||| || ||| || ||| || ||| || ||| > jason kanter * piano tuning * piano teaching > bellevue, wa * 425 562 4127 * cell 425 831 1561 > orcas island * 360 376 2799 > || ||| || ||| || ||| || ||| || ||| || ||| || ||| || ||| 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
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