downbearing (was steinway D)

[Oleg Isaac]

Newton, Frans, 

I appreciate a lot all of your mail.

Regarding bearing, I wonder if there is a relatively accurate method to
mesure the crown of the sounboard ?

I've learned to put a typical 3 mm in the bass , going to 1.2 mm in the
extreme treble on the pianos whe where re-stringing 18 years ago.

The two last stringing job i've done (last year in fact, I computed the
bearing to have a 2° angle in the center, going to 1,5) at the extremes.

Is an excessive downbearing in the extreme bass and treble (without a
suspended bridge for the bass) susceptible of blocking a bit the ability
of the sounboard to amplify nicely the sound.

I have seen some grand pianos with a full 3 to 5 mm bearing on the
treble bridge STRUNG , and a harsh , non-singing sound in this section.
How can the sounboard get this big crown in the treble (there was) ,
only humidity ?

Something comes to my mind just now . I wander if the CAPO BAR on
BOSENDORFER, is regulation-nable, (strung) beacause of the many screws
wich seems to hold it ?

For the matching of the crown and downbearing, I always had put the
bearing approximately, try not to stress too much the sounboard, (of
corse if collapsed, or if too much crown) I heat the table a bit before
any stringing , trying to stabilize it.

Back to the first question. Is there a method to match
crown/downbearing. ?

If 3mm to 2,5 mm on the bass bridge, and 2,5 mm to 1,5 mm mm on the
large bridge, are not the bass strings taking too much pressure off the
middle strings when strung ? (causing a lack of power in the middle? )

Best regards, I hope all my questions are not too much...

IsaacFrans Sedee wrote:
> 
> Isaac,
> 
> The gauge you describe enables you to check if the string moves up to the bridge
> from the agraffe (or capo bar or whatever) and then back down again to the
> hinge pin
> in the frame.
> This is the information you need.
> I learned to take a piece of thin rope, lead it through the agraffe, let it
> touch the
> bridge, and at the end observe how high above the hinge pin the rope would end.
> This was done before any stringing. If there would be 3-5 mm "downbearing"
> in the bass
> section, decreasing untill about 1-2 mm in the treble, the instrument would
> be ready
> to string. Ofcourse this way the length of the string after the bridge was not
> considered. I think this method is not enough, but it is a result in mm.
> We should be able to measure the angles that the string is making with a
> straight line
> from agraffe to hinge pin, on both sides of the bridge, to really be able to
> speak of
> downbearing.
> 
> As far as American tools and lubricants are concerned; a lot of it is
> imported in Holland
> you can email me what you need. Say hello to monsieur Guillemenot for me if
> he can't help you.
> 
> Frans Sedee, stemvork@xs4all.nl