[pianotech] Bobbling hammers and jack spring pressure?

[CALANDE Luc]

Perhaps you could have to look on the jack-stop rail (see here under from the list) that could be too close ?

Luc

----- Original Message ----- 
From: <pianoguru at cox.net>
To: "Pianotech List" <pianotech at ptg.org>; "Mark Wisner" 
<markwisner at earthlink.net>
Sent: Friday, August 22, 2008 2:49 PM
Subject: [Norton AntiSpam] Re: Yamaha U1


> The jack rail is effective in improving repetition..  Julia, you'll notice 
> that in other upright actions there may be felt on the back side of the 
> let-off rail to serve the same purpose, or a felt block on the jack near 
> the top, or a smaller felt block on the back of the catcher, all serving 
> the same purpose. The difference is that the rail is adjustable, to 
> achieve the absolute minimum of necessary movement away from the hammer 
> butt.  The same screw that mounts the rail is the adjusting screw.  If the 
> threads of the screw were the same along its length, turning it would 
> affect no change in the rail position, but the threads through the rail 
> are "faster" threads than at the tip where it enters the main rail, 
> allowing for the tiny bit of movement to finely control its adjustment.
>
> Frank Emerson
>
>
> ---- Mark Wisner <markwisner at earthlink.net> wrote:
>> It's a jack-stop rail, and supposed to keep the jack from whipping too 
>> far on back on a very hard blow.
>>
>> -----Original Message-----
>> >From: KeyKat88 at aol.com
>> >Sent: Aug 21, 2008 6:15 PM
>> >To: pianotech at ptg.org
>> >Subject: Yamaha U1 "extra" rail
>> >
>> >Greetings,
>> >
>> >     What's with the extra rail in the front of the  Yamaha U1 action? I 
>> > have
>> >never seen this before. Its down in front near the  letoff rail
>> >
>> >
>> >Julia Gottshall
>> >Reading, PA
>> >
>> >

  ----- Original Message ----- 
  From: 
  To: 
  Sent: Wednesday, January 21, 2009 5:22 PM
  Subject: [pianotech] Bobbling hammers and jack spring pressure?


  List,

  is there a way to ease the jack spring? I have problems with a Yamaha P121N upright that has bobbling hammers. The hammer butt is dancing on the jack tip. All regulation measures are okay and there is enough aftertouch. I suspect the jack spring being too strong. Any thoughts how to get it right? 

  There is no lost motion, check is about 15 mm, aftertouch is okay and I gave some talkum powder to the jack tip and the let off button. The only thing that helped was to set the let off to 10 mm, but that´s not a satisfying solution. The strange thing is that one could play without bobbling hammers but something makes the player stop pressing down the key before the let off point. A very subtile resistance gives the player a hint that the key is pressed down now, but that´s not right. The player could and should press further on. The strange thing is that this problem is new for a few days. I should mention that we had very dry air last weeks and the customer has a floor heating. Therefore I suspect a connection between this problem and the dry air.

  Any comments?

  Gregor


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