post pitch-raise creep?

[Farrell]

Doesn't sound right. When doing the PR, are you using an ETD? Unisons as you go? 41% is very large percentage for overpull. Most ETDs recommend between 20% and 35%, depending on the area of the scale.

Immediately after the PR, do you check the middle section for pitch? If it is at or near target, there is no reason for it to creek up. How large a pitch gain are you talking about? I've never noticed such a phenomena.

Terry Farrell
  ----- Original Message ----- 

      I do many many many pitch raises -- almost every piano I tune, for the last 27 years.  (Almost everybody lets them go too long.)
      I've found that the ideal average overpull is halfway between 1/3 to 1/2 the amount sharp as it was flat.  In other words, a 41% overpull of the amount it was flat.  For an easy-figuring example, say the piano is 18 cents flat.  Half of that is 9 cents and a third of that is 6 cents.  Half-way between 6 and 9 is 7.5, so I pull it 7.5 cents sharp, and almost invariably A4 ends up right on 440 Hz, or very close.  
      However, if the piano is a half-step flat, I don't pull it 41 cents sharp.  That would be too much.  There's some degree of flatness where the usually-ideal 41% overpull has to taper off.  For a half-step pitch raise, I usually overpull so that A4 is beating about 5 beats sharp.  That's approximately 20 cents, I believe.  Sometimes more is required, sometimes less.  It varies.  That's here in Denver -- probably different elsewhere.  
      But what I often experience is:  even though after the pitch raise, A4 is at 440; after I've gone through the fine tuning and      pulled in unisons, when I go back to do the final check and touch up anything that has slipped, I find that the whole middle section is sharp!  Why?
      --David Nereson, RPT

-------------- next part --------------
An HTML attachment was scrubbed...
URL: https://www.moypiano.com/ptg/pianotech.php/attachments/20060707/75420af1/attachment.html