drop adjustment

[Newton Hunt]

What Ed has written is right and very good.  Level the keys, set
hammer blow distance at 48 mm, the let-off at 2 mm and drop 1 mm below
that.  Dip must be 10 mm +.5 mm -0.0 mm or 0.394" measured just behind
the key lip.  Repetition lever must be set so the jack just barely
brushes the knuckle when the toe is pushed down with a finger and the
back edge of the jack is aligned perfectly with the back edge of the
knuckle insert.  Checking is 15 mm or 5/8".  Spring tension should
raise the hammer firmly but not so it bounces on top of the rep.
lever.

Take a micrometer and measure the thickness of your dip block at each
front corner and sand it until each measurement is within 0.001". 
Write this number on the  bottom of the block so yo won't forget it. 
If it is different than 0.397" then you can add or subtract a paper
from each key to get the exact dip you want.  After finishing the dip
on the white keys then depress three keys together and run you finger
back and forth to try to determine if one is lower or higher than the
other.  Go up one white key and repeat.  Do the entire keyboard this
way.  

Procedure:

Level keys
Set jacks to knuckles
Set repetition lever height
Dip naturals
Hammer height
Let-off
Drop
Dip on sharps (to make the safety factor the same as on the naturals)
Sprint tension
backchecks.

Safety factor is defined as the distance from the point the jack
leaves contact with the knuckle to the point where the key stops. 
Varying your touch pressure can effect the safety factor.  Change dip
to change safety factor but only after all the other procedures are
done.  Drop has to be checked after changing the dip, always.

Safety factor is from 0.040" to 0.050" or about the thickness of a
penny.  Add 0.040" under the key and check for let-off.  If there is
let-off AND drop there is too much dip.  If there is no let-off the
dip is too shallow.  COrrect safety factor is let-off but no dropping
of the hammer.

Make sure the hammers are off the rest cushions, the action is screwed
down securely, the spread action has not been changed and that the
rails are as straight as a fine thread can be.  If it is a really old
G-2 with the Schwander style action (wooden action rails) then make
sure the hammer rest rail has not been improperly set.  It should be
3-5 mm below the shank when the blow distance is set at 48 mm or 1
7/8".

Yamaha action setup in the factory is superb so there should be now
problem there unless you suspect someone as messed with the spread
action measurement.  I don't have those numbers with me here but you
can get someone to post them is you need them.

Lots of luck and if you still cannot get it to work right just holler.

		Newton


> Greetings, 
>    I set drop at the same distance from the string as I do let-off.  They are 
> both dependant on the string excursion zone to set the limit on powered 
> hammer travel.  
> The springs need be set to lift the hammers from check as fast as possible 
> without being felt in the key.  
>   The aftertouch is dependant on three things:   hammer blow, let-off, and 
> keydip.  It is inversely proportional to the first and proportional to the 
> second and third.  Finding the optimum setting for the three requires that 
> you start from somewhere, and usually for the Yamaha, 1 3/4" blow is a good 
> place.  Set 1/16" let-off and 3/8" keydip and see what you have for 
> aftertouch.  If you need more,  lower the keydip first to .395 or so.  After 
> that, you may need to raise your hammerline,  but .020" of aftertouch is 
> enough for most of these pianos.  
> Regards, 
> Ed Foote RPT