D.H. Baldwin

[David C. Stanwood]

David Ilvedson wrote:

>I tuned a D.H. Baldwin 5'10" grand today.  The action felt 
>terrible and while servicing I noticed it had helper springs on 
>the wippens.  Then I noticed only one key lead in the bass up 
>to tenor then none.  Obviously the helper springs are a big 
>savings in manufacturing over weighing off the keys.  I didn't 
>take down/up weight but it was heavy with lots of up weight.  
>Can this be made to play with just the helper springs?  Of 
>course the hammers are big and heavy with little weight 
>removal done in the factory.  

Dear David and list,

To tell how hard the springs are working, measure up weight then disengage
the spring and remeasure upweight.  The difference in the two measures will
tell how much the spring is working down the UpWt/BalanceWt/DownWt.  Renner
makes three sizes of springs. 0.70mm, 0.60mm,  and 0.55mm.  The heaviest of
these shouldn't be asked to work down the touchweight by more than 25 grams.

To tell how heavy hammers are, the weight has to be measured and compared
to reference zones in order to make a judgment.  (Article on this coming in
the March Journal).  In the mean time you may refer to the set up for
measuring hammer weight on-the-shank using strike weight at: 

http://www.stanwoodpiano.com/swsetup.gif

and the reference zones at:

http://www.stanwoodpiano.com/swranges.jpg

Leverage is a big issue and levels vary a lot in today's pianos.  It is
often the culprit when it comes to heavy action.

Determination of sample strike weight ratios and computing the average is
one way to assess leverage.  If strike weight ratio level is above 6.0,
strike weights above mid medium zone are trouble. Lower than 6.0 is
recommended for strike weights above mid medium.  If strike weight ratio
levels is below 5.0, you'll be needing too much dip to regulate.  If ratio
is above 6.0 you have a green light to move the capstan line forward
towards the balance rail without fear of creating problems.  Don't move the
line so much that excessive dip is required and respect the rules of
geometry.  Consult a specialist on this if need be.
 
Helper springs won't fix a bad combination of hammer weight and overall
action ratio,
but they do "Help" and used properly they are a great resource which
lighten the action somewhat and improve repetition by reducing keystick mass.

I'll be teaching a full day seminar on this stuff at the CA State and other
seminars:

http://www.stanwoodpiano.com/PTG.htm

Hope to see you there.

David C. Stanwood