Downbearing

[Daniel Lindholm]

Hi!

First of all, thanks for taking the time to answer my post. 
I didnt think I would come online before monday, but I 
did :)

I was expecting to have to straighten some things out, 
since english isnt my mother tounge, so here are some more 
questions and some explainations.

>   More information would be helpful in diagnosing your 
dilemma 
> but I suspect there is an error perhaps in the way you 
are measuring bearing. 
> How was that done?
We usually use those simple tools sold by all pianotech 
companies that you put over the bridge, measuring the angle 
of the string right over the bridge. So we could not have 
misstaken zero downbearing for positive downbearing. When 
the strings where off we used a strong thread through the 
agraffes and down over the bridge.

That the downbearing decreases noticable is something we 
all have noticed at school. It always happends. Sometimes 
little, sometimes alot as in this case. Thats why I wanted 
to discuss it.

So, it didnt have zero downbearing anywhere. Thats why we 
can exclude the idea of the strings actually lifting the 
soundboard upwards when the strings were there.

>  You did not mention crown. Did you check it before and 
then after it was 
> unstrung  with a string across the bottom of the board. 
I've been fooled by 
We only measured the crown after the strings were removed. 
It had some crown, but it wasnt much (I really dont know 
how to define much crown though)

> > Then I formed a second theory about the dissapearing 
> > downbearing. Could it be that the strings actually 
> > compresses the cast iron and the cast iron compresses 
the 
> > whole soundboard giving it a part of its crown in that 
way? 
> 
> >>>>>>>>>>Are you using crown and bearing as 
innerchangeable concepts? 
What I meant was that when the strings are in place, with 
that incredible tension the whole cast iron was compressed 
from the pins to the bottom bolts where its hold firmly 
together with the frame all around the pianos rim. This is 
just a theory, but perhaps the crown of the soundboard then 
increases as the whole piano is clamped together of the 
stringtension, giving the soundboard a slightly bigger 
crown of the soundboard.

What do you think about that? 

I cant find any other solution to why the downbearing 
decreases alot when you remove the strings.


> >>>I usually don't because if it has ehough when the 
strings come off I can 
> reuse the board and if not it gets a new one. I honestly 
put more stock in 
> the way the piano sounds before it's torn down than any 
physical 
> measurements. For example I've had some amazing sounds 
come from boards with 
> no crown and minor amounts of bearing so what do I care 
what the measurements 
> are. I've also had fully crowned 9 ft kawai piano les 
than ten years old with 
> 10 mm of crown strung and no bearing. I hated the sound. 
Both in this case 
> were verifiable with measurements.
>  Hope this helps
Yeah, I totally agree. If it sounds good, why bother. :)

Thanks,
Daniel Lindholm