Rib Crowned Hamburgs ?

[Farrell]

"...they resembled the setup Terry Farrell posted pictures of a while back."

Darn, I knew someone would copy them......should've done the copyright 
thing......

"...the same as pure rib crowning procedures so enthusiastically debated 
back and forth on this list..."

It may essentially be pure rib crowning they employ (much to my surprise, 
for sure), but there is more to designing a soundboard than crowning a rib. 
What is the taper design? What is the rib array? Rib dimensions? Rib 
radius/radii? Radius/radii of caul(s).

Not to mention the panel design.

It could also be the case where they machine a 60-foot radius arc into a rib 
and press it into a tighter caul - that would induce compression crowning.

Still many unanswered questions, but yes, definitely interesting. Thanks for 
sharing.

And besides, I didn't think hamburgers had any bones....?

Terry Farrell

> Just back from 2 weeks at the Hamburg Acadamy and just had to share with 
> one and all a most suprising experience I had whilst there.  As part of 
> the acadamy cirriculum trainees are given a 3-4 hour long tour of the 
> factory. Many fascinating elements of the Steinway Hamburg production 
> methods were shown, and there was absolutely no discernable attempt to 
> hide anything. We went through virtually every room in every production 
> building and saw every stage of the production.
> In the course of the questions and discussions that took place underways I 
> (true to all previous adventures) jumped at the opportunity to ask about 
> how Steinway soundboards are put together and I was told that in the 
> Hamburg factory the panel is only dried to somewhere between 6 and 7 
> percent EMC before ribs were glued in place. I immediatly double 
> questioned this and was assured this was, and always has been the case at 
> Hamburg. The ribs are machine crowned and the caul is curved. So you have 
> a mildly dried panel with machine crowned ribs pressed into a curved caul 
> ! After expressing my suprise I was told that we would be viewing the 
> soundboard assembly room in a little while.
>
> The room itself  was rather small really. No sign of a hotbox anywhere. 
> Curved ribs ready for installation were a plenty. Two glueing presses were 
> clearly visable and tho I only caught a quick glimpse of these they 
> resembled the setup Terry Farrel posted pictures of a while back.  I asked 
> once again about the panel EMC and lack of a hotbox and was told simply 
> that the buildings are all held at a low enough RH to insure 6-7 % EMC in 
> all woods used for all production elements.
>
> After the ribs were glued and dried for 6 hours, they trimmed (weakened) 
> the ends of the ribs which allowed the panel to curl up against the 
> lessened holding power of the ribs where trimmed. This was said to create 
> a kind of spring effect for the outer perimeter of the soundboard.
>
> There was a hotbox in another room for a much latter stage of production. 
> This was when the entire assembly was to be fitted to the rim and the 
> plate fitted in turn to both. The purpose for this hotbox was to insure 
> maximum stability for thesoundboard assembly (including bridge) during 
> this entire process.
>
> Anyways, as this whole proceedure is essentially the same as pure rib 
> crowning proceedures so enthusiastically debated back and forth on this 
> list, I thought it would be interesting for you all to hear about it.
>
> Cheers
> RicB