( new Yamaha w/bobbling hammers)

[antares]

On 13-apr-04, at 21:50, Richard Brekne wrote:

> Hey there Andre'

Ricardo Mio,
>
> You illustrate one of the main points I was trying to make really well.

This is again proof of a vibrant and razor sharp intelligence,......... 
ta da ta da!!  (; >)) )) ))  (by the by, yours or mine?, I 
forgot....duh)

> Bobbling caused by hammer butt bouncing off the jack means really one 
> of three things is going on..
>
> 1.  The action is simply regulated wrong,
> 2.  There is a design flaw with the angle of the jack that makes is 
> borderline impossible to get it easily out from under the butt to 
> begin with.
> 3.  Something is impeding the jack travel at the bottom of the 
> keystroke.
>
> The first two are easy to address and rule out of the picture.  If you 
> do that first then all that remains is the 3rd,  so you look at things 
> that can slow down or resist jack travel at the bottom of the key 
> stroke.  Friction can definantly be an issue here for sure.  I like to 
> manually travel the jack with a capstan regulator to feel the contact 
> between the jack top and the hammer butt, and to check return spring 
> strength.  I can also check to see how stiff the jack feels pulling 
> out in general this way... and how far it actually is allowed to 
> travel.   I've never yet been totally stumped without the problem 
> being the second mentioned above.

I agree Ric, There err.. ah.. is a problem here ah, and maybe the techs 
at Yamaha are not aware of it.
However, I have noticed this problem a long time ago and that's how I 
came to my conclusions.
All we can do is work on the friction points, (very err.. ah.. 
important here), make a sharp and uniform 2 mm let off, and if 
necessary, make the striking distance somewhat smaller  to say 44 mm. 
Oh yes, and like you said... give the jacks some "Luft".. (The Luft 
Waffe) (; >))

André



>
> antares wrote:
>
>> Hi Gordon,
>>
>> I too have wrestled with this Yamaha upright problem.
>> According to me, the angle and position of the jack is such that it 
>> is hard for the jack to away get from under the butt.
>> I have tried several things myself in the past.
>> 1. I used a thicker cushion, which immediately helped but the hammers 
>> lost power, so no good.
>> 2. When encountered with this problem, I always take out all the 
>> keys, spray the balance and front rail pins with McLube, and make 
>> sure that the keys have very little friction.
>> Any friction before the jack movement may add to the problem. A more 
>> or less friction free start helps the jack to get out from under the 
>> hammer butt.
>> 3. I made the striking distance smaller by gluing some thick red felt 
>> on the hammer rail rest. Thus helped very much because the angle and 
>> position of the jack improves, but you lose some power because the 
>> striking distance gets smaller. A compromise may be the answer : 
>> raise the hammer rail just a bit and adjust the action.
>> 4. I have noticed this problem also, and in particular, with Schimmel 
>> uprights. Lubing the jack heads with McLube helps immediately and is 
>> extremely effective, especially in combination with a sharp 
>> regulation.
>> With plastic jacks however, you have to be very careful and not spray 
>> too long and too much, the plastic may turn into a candle.
>>
>
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friendly greetings
from
André Oorebeek

Amsterdam -
The Netherlands

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