My most heartfelt thanks, BUT........( new Yamaha w/bobbling hammers)

[Richard Brekne]

Hey there Andre'

You illustrate one of the main points I was trying to make really well.  
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.

RicB

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.
>