Crowning one rib at a time

[Richard Brekne]

Ah... so its not so much a matter of crowning the board itself  rib by 
rib as it is a matter of installing ribs one at a time due to space 
concerns and the ability to reposition ribs on the fly...  yes ??  I 
understand you dry your panels down quite a bit before installing the 
ribs. How much working time do you allow for in getting all ribs 
positioned and pressured after the panel comes out of the box ?

I'd love to see a picture of your basic setup. We've seen several 
variants posted here through the past few years.  The more the 
merrier... and the more enlightening as it were.

Thanks for the reply
RicB

Michael Spreeman wrote:
> Hi Ric,
>  
> No problem. Some factories have presses with a slotted perimeter to 
> position the ribs on the panel. They can do this because they are 
> producing numerous boards with the same rib scale and layout.  The 
> presses have a frame with pre-positioned arms that come down to the 
> ribs as a unit and are inflated all at the same time. Our press 
> consists of several indivual units that are positioned one at a time. 
> This allows us to enact changes in the rib layout from piano to piano 
> without having to reconfigure a large fixed press. We have limited 
> space in our shop, so another advantage to individual frames and 
> cauls is the ability to store the presses in a small area when not 
> being used. Also, our press frames have removable cauls which allows 
> us to remove one caul and replace it with another of a different 
> radius if desired.
>
> /                Michael Spreeman
> /http://www.spreemanpianoinnovations.com 
> <http://www.spreemanpianoinnovations.com/>
>
>
> ------------------------------------------------------------------------
> > Date: Mon, 4 Aug 2008 09:22:16 +0100
> > From: ricb at pianostemmer.no
> > To: pianotech at ptg.org; m_spreeman at hotmail.com
> > Subject: Crowning one rib at a time -- Spreeman
> >
> > Was reading about the Ravencroft instrument and have been curious about
> > many things since first hearing about it. On the website it says
> > somewhere that the soundboard is crowned "one rib at a time". I wonder
> > if you could be so kind as to expound on that a bit. Exactly how do you
> > crown a board one rib at a time ?
> >
> > Thanks if you can find the time to explain
> > Cheers
> > RicB
>
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