Grand Touch

[Roger Jolly]

Hi Ric,
               You have good down and up weight, so friction does not seem 
to be a problem.   Excessive after touch can lead to this kind of problem. 
Two causes:  1.  The height of the balance rail hole is too tall. It needs 
to be 4mm on a spruce key, or 3mm if the key has a maple shoe at the base 
of the  BR hole.  ( My bet on the cause)    2. Very soft or springy FR 
cloth punching's

1.    When the hole is too tall your fingers start to feel the key binding 
as the wall of the hole starts to jam against the balance rail pin, at the 
bottom of the key stroke. It will make refined after touch all but 
impossible to achieve. Forte supply sells a reaming tool so you can ream 
the  BR.  The tip is 4mm in length. (A pic was post on the list about 2 
months ago. I'm on the road and the pics are on my desk top)
Hold your finger firmly on the bottom of the hole and ream away until you 
just feel the tip touch your finger.

The balance rail holes may have been over eased with a Yamaha style reamer 
to solve the problem.   As such the hole may be over sized to mask the 
problem.  This leads to a  tendency to chuck.
Lay a damp cloth over the holes and iron the cloth with a hot iron to swell 
them up. Ideally leave them out of the piano for 24hrs.
Refit keys to action and size holes as required.

You most certainly will have to reset the dip. 9.5mm to 10mm is where I 
would expect to see it. The piano should  regulate well with about 0.020" 
after touch, and the key sitting in good contact with the FR punching.

2.  Installing Crescendo punching's from Forte supply will make the after 
touch very well defined and will enable you to shorten the dip a 
little.  Well worth the money on this quality of piano.
I have recently returned from the Petrof factory and voiced my concern, 
that both these items were a problem. They are now looking to make changes.

Hope this helps.
Regards Roger





At 08:12 AM 7/11/2006, you wrote:
>Hello List,
>I am now looking after a 12 year old Petrof concert grand which has been 
>aquired by a church for recital use etc.  It is a super piano tonally and 
>in great condition, but it looks as though I will have to attend to the 
>touch in the near future.  I have played it extensively myself and had a 
>top rate professional pianist try it out and the basic problem appears to 
>be that it becomes tiring to play because the touch 'appears' heavy.  On 
>measuring the touch weight weight however, it comes out at an average of 
>48g (easy) downwight and 28g up. Present regulation is very good.  It is 
>Renner action with smallish Renner hammers which I am sure are original. 
>The action ratio is in the 5.5 range.  It has to be said that I 
>intend  taking the action apart and check out all the centering and any 
>key friction, and I expect this to make the touch more even.  That 
>said,  I still appear to have a fundamental problem which I will need to 
>be addressed, and I am asking for comments and ideas on how to approach this.
>Don't hold back!
>
>ric
-------------- next part --------------
An HTML attachment was scrubbed...
URL: https://www.moypiano.com/ptg/pianotech.php/attachments/20060711/b7d20c9e/attachment.html