Touchweight Metrology Question

[Farrell]

Hello Roger! I just regulated notes #28&29 and 40&41 - 28 & 40 are naturals and 29 & 41 are sharps. I set the blow distance at 47.5 mm, and let off at 1/16", or about 1.6 mm. Action spread is exactly at 112.5 mm. I have after touch right at about 0.025". Dip on the both naturals is between 10 and 10.5 mm, and dip on the sharps is right close to 10 mm exactly. 

I don't really know how much the natural KR of 0.50 and the sharp KR of 0.48 should affect the dip. I hope these numbers don't relfect my poor measurement techniques (eyeballing with a small ruler).

Waddayathink?

Oops - I'll go out and look at the majic line thing.

Terry Farrell
  
----- Original Message ----- 
From: "Roger Jolly" <baldyam@sk.sympatico.ca>
To: <pianotech@ptg.org>
Sent: Thursday, May 16, 2002 8:46 PM
Subject: Re: Touchweight Metrology Question


> Hi David,
>           I think I would agree with you. My thoughts is that the stack is
> mis located, or the rail needs re locating. But I would like to see the
> friction more even, and have the dip measurement with .010- .015" after
> touch, before making some kind of judgement.  I would bet this action works
> with 9mm or less dip.
> Dip spec is 10mm.
> I have found that dip gives all kinds of clues, along with the status of
> the magic line. I have fixed far too many troublesome actions, just working
> with these two parameters.
> Yamaha over the years have been remarkably accurate with the sizing of
> their components. The way they install key leads, and capstans, is also
> consistent, and almost fool proof.
> Rail installation is the most common variable that I have found.
> The key pins on this vintage are brass, and are prone to tarnish, hence my
> concern about cleaning up friction issues first.
> At this point I would like a little more imformation.
> Regards roger
> 
> 
> At 10:57 PM 5/16/02 -0700, you wrote:
> >Bill:
> >
> >I'm not sure I would agree with your assessment of putting 18mm shanks on
> >this piano.  The SWR for the naturals is already 5.5 on average (some are
> >even lower if the measurements are correct).  If he puts on an 18 mm shank
> >it will lower the ratio to under 5.  That's too low and will create some
> >regulation problems.   The BW's are erratic because the KR is different
> >between the sharps and the naturals (.50 and .48 respectively).  This has
> >created a different ratio between the sharps and naturals and has resulted
> >in erratic balance weights even with a relatively smooth SW pattern.
> >
> >David Love
> >
> Roger Jolly
> Balwin Yamaha Piano Centres.
> Saskatoon/Regina.
> Canada.
>