[pianotech] beginner's calibration question

[Zoe Sandell]

Thanks John,

My room temp is 20 degrees.  I wondered about the specifics of temperature-
certainly the manufacturers could not mean that the fork itself is 20
degrees and not the room? As steel will always be colder than its
surroundings- cannot recall the exact science behind the difference in heat
conductors.  I guess the underarm trick simply adjusts the fork enough to be
accurate?

I wonder about the fork- I will take mine into a master tech- to do any
filing- but this will likely be necessary.

Zoe


-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of John Ross
Sent: December 28, 2009 12:12 PM
To: pianotech at ptg.org
Subject: Re: [pianotech] beginner's calibration question

If you are sure that the fork is off, remembering that temperature has an 
effect on it, some people put it under their arm for a predetermined time 
before measuring.

As a matter of interest, just how accurate should a fork be?        +/- 
what?

The fork frequency can be changed with a file.
I think I remember correctly, I am sure someone will correct me if I am 
wrong. :-)
Take some off the tips to raise the frequency, and some off the inner part 
of the leg to raise the frequency.

John Ross
Windsor, Nova Scotia.


----- Original Message ----- 
From: "Zoe Sandell" <yiddishtangofever at shaw.ca>
To: <pianotech at ptg.org>
Sent: Monday, December 28, 2009 4:01 PM
Subject: [pianotech] beginner's calibration question


Hello,

I have just completed calibrating my tuning device with NIST and the Tunelab
demo-.  When I call back the C5 500Hz marks as in tune- ie squares stay
still- but my tuning fork reads flat at A440

How then do I accurately tune the temperament octave to the tuning fork-
knowing this discrepancy?  Get a new/better tuning fork?

Thanks
Zoe