Shopping for a Belly

[Ron Nossaman]

>You need to replace the soundboard in piano X. We either know it 
>originally had a compression crowned board or we simply do not know about 
>the original crowning method. But we know we want a rib crowned board.

We certainly do.


>So what do we do. Most folks will either make a new board themselves by 
>copying the original dimensions or perhaps they will order a "board in a 
>box" from one of several sources. These also will be "copies" of the 
>original board dimensions (panel thickness, rib cross sections, rib 
>array). To the best of my knowledge at least several (if not all) of these 
>"board in a box" sources rib crown (at least partially) their boards.

Don't know.


>Now I'm no soundboard designer, but it seems plain as day to me that as 
>soon as you cut a radius into those ribs, you are changing the design of 
>the soundboard.

Yup.


>  You are changing the load capacity of those ribs.

Yes, but from what - to what?


>The amount of panel compression should also affect things. If the ribs can 
>support more load, maybe we want smaller ribs.

And different rib cross sections, and different lengths and feathering, and 
maybe more of them, and maybe at different angles than the original ones.


>Maybe we want a thinner panel. Maybe, maybe, maybe. Who knows? Yet we are 
>maintaining the original rib dimensions. Is it just done that way because 
>we don't know what else to do?

Yes, and it's considerably faster than more extensive redesign. Easier too. 
It's not necessary to try to work out what those ribs are actually doing, 
and make decisions on what you want them to do, and why.


>It seems to me this approach is a shot in the dark. Perhaps with a few 
>pianos, such as Steinways and Mason & Hamlins, this approach has been 
>tried enough times and one can have some reasonable expectations about the 
>results. But what happens when you replace the board in an old Weber, or 
>an old Decker Bros., or an old A. B. Chase or many others? Take a shot in 
>the dark?

Essentially. You try to turn on as many lights as possible beforehand with 
what education you can find, buy, soak up from someone else, and generate 
for yourself by application and expenditure of large quantities of time, 
effort, cash, and sacrificial brain cells. It's not a shot in the dark, but 
it's still a series of judgement calls.


>Someday, if my soundboard building thing smoothes out, I would really like 
>to start providing some belly services to other local techs/rebuilders who 
>do not do soundboards. Great! But I know someone (likely with a Steinway) 
>will tell me that they don't want to change the belly design - just 
>reproduce the original. Well, I can't for the life of me imagine building 
>a compression-crowned board (I won't do it!). And I'm not going to just 
>reproduce the original dimensions and arbitrarily crown the ribs - who 
>knows what will result. So what does one do in this case?

It hasn't come up for me yet, but I'd either get to at least adjust some 
rib depths and crown them, or they could take it elsewhere. I did the 
reproduce the original with 60' crown addition thing when I first started 
out, and wasn't awfully happy with the results, but I wasn't rescaling, and 
didn't know much of anything else then either, so I don't really know where 
the worst of the problems came from.


>That leads me to another thing that bugs me. (Like you really want to hear 
>this?) I have run across several apparently highly respected, obviously 
>very skilled, very experienced, etc., etc., rebuilders who go to great 
>lengths to "reproduce the original piano exactly". They don't even want to 
>rescale the darn thing (not picking on anyone in particular - I have heard 
>this philosophy many times). But, they go right ahead and replace the 
>original compression crowned soundboard with a rib crowned soundboard. 
>They change the very heart of the piano. I don't get it.

But don't they then dry the panel down to near 4% and compression crown the 
rib crown? Doing that, they'd get a better supported compression crowned 
board than using flat ribs. What we say we do is inevitably different than 
what we think we do is different from what we actually do is different than 
what we think we did differs from what the customer thinks we did is 
different than what another tech sees and is sure that we have done - 
whether we did it or not. First you think, then you try to do what you 
think is right, by your thinking, and everyone else will think, or feel, 
what they will think, or feel, regardless of what you think, feel, or do. 
It's a zero sum game. For every truth you establish for yourself, someone 
else's will be outraged.


>I'll go to bed now. Grrrrrrrrrrr.   ;-)
>
>Terry Farrell


Rest up. It'll still be there tomorrow.

Ron N