[pianotech] FW: laminated ribs again

[Euphonious Thumpe]

Not at all meaning to "pick on you", Del, but my 1899 Knabe has laminated ribs. I doubt they're anywhere nearly as scientifically designed as yours, but it's nice to know someone also "came up" with this idea, "way back when".  Has anyone here pursued laminating ribs on old soundboards "in situ" to improve lost crown? ( With a thin strip added to the spine of the old rib, in a compressed caul? ) I'm considering experimenting with this method, on a really crummy old upright, strings in place, with a  collapsed board. 

Euphonious Thumpe


> I've probably been using laminated ribs longer than
> anyone else in the business.
> One of the reasons I became interested in laminated ribs
> was the inconsistency
> of ribs cut from solid stock. Both the mass and stiffness
> of conventional ribs
> varies widely depending on the physical characteristics of
> the wood from which
> they are cut. By building up the ribs using thin strips of
> wood of varying grain
> characteristics both the mass and stiffness of the
> laminated ribs tends to be
> more predictable and consistent.
> 
>  
> 
> Back when I was experimenting with the process I did do
> some testing to
> establish a basis on which I could calculate rib stiffness.
> The primary impetus
> for developing laminated rib technology was to be able to
> predict the acoustical
> performance of a rib-crowned soundboard system so I needed
> to know how they
> would react under load. I would suggest anyone switching to
> laminated ribs do
> the same. I've always thought it a good idea to have a
> thorough personal
> understanding of the systems and materials with which I
> work. 
> 
>  
> 
> Yes, I do follow a criteria for scalloping ribs. The
> description of what I do
> and the explanation of why I do it is rather more involved
> than I care to go
> into on this list but it is something I cover in several of
> my all-day seminars.
> Others probably do as well. You might check the line up of
> classes being offered
> at the Annual PTG Convention this year. I don't know
> just what is being offered
> but there might well be something on this topic. 
> 
>  
> 
> ddf