Crowning one rib at a time

[Farrell]

Richard - that's basically how your Bluthner laminated board was ribbed.

Terry Farrell

----- Original Message ----- 
From: "Richard Brekne" <ricb at pianostemmer.no>
To: "Michael Spreeman" <m_spreeman at hotmail.com>; "Pianotech List" 
<pianotech at ptg.org>
Sent: Monday, August 04, 2008 2:56 PM
Subject: Re: Crowning one rib at a time


> 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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