laminated ribs

[Erwinspiano@aol.com]

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In a message dated 2/18/2006 9:26:00 A.M. Pacific Standard Time,  
rnossaman@cox.net writes:


Dale wrote
>   Ok Now I,lm confused.   If were only trying to support only 400 to 600 
> lbs. of down bearing  force as Del inferred recently or whatever one 
> calculates this to  be,  then what's all the fuss about.  

My loading of new  boards these days is typically half again 
over 600  lbs.

Ron, so you are saying a 900 lb bearing load is  probably an in the ball park 
average plus or minus for various sizes of  pianos  & string scale tensions.
  Then  my comment a couple weeks ago about  bearing being 1000 lbs  or more 
depending on who you ask wasn't that far  off this figure even though Del 
disagreed with that as  being  "excessive."

>It's  not that 
> much of a load.  I've never seen ribs sheer, break or  explode under 
> bearing.  I've seen compression crowned boards  with fat crown & 
> bearing after 40 , 50 , 60 years or more that  sounded wonderful & the 
> ribs still intact & of course others  that didn't.

Ron Wrote------- No, the  ribs don't usually explode, but I have seen broken 
ribs in the high end  two or three times. In this part of the 
country,  it's rare to find old compression crowned boards with  
decent crown and bearing.
     Dale wrote---In our area we see it  fairly commonly up to about as old 
as 60 years.  But these survived in the  bay or on the coast where temperate 
climates are the rule.

The ribs  do other things in these boards like straighten out when the 
> crown  deflates but a stiff spruce crowned rib with nice tight straight 
>  grain & a laminated rib in my mind will do just about the same thing for  
> as long as we want them to if designed to handle the appropriate  loads. 
> And they will do it for a tremendously long time reliably. I  like the 
> whole laminated rib thing & all & there pretty in a  techno sense too but
>    I'm just throwing out the question  is it overkill?
>   Flame suit on & feelin onry  today
>    Dale

Could be. Laminating costs me time to  glue them up, but saves 
me time to cut them out. It uses spruce with  grain angles and 
color defects that would otherwise not be usable in belly  
work, so it's good conservation of materials. I like that part 
a  lot, but then I'm still laminating bridges from salvaged 
maple  racquetball court flooring.
  All that appeals to me as well.  Hey maple is  maple.  I'm still making 
bridge caps from an upright that was made from  solid beautiful maple ...every 
last piece

In fact,  at the cost of a 
little extra time, I can build up ribs over two or three  
clamping's, that use up the shorter cutoffs that would 
otherwise be  trash, on the rib bottoms where the feathering 
would cut away and waste  good wood anyway. See photo. I also 
found it bothersome to bend, clamp,  and try to rip ribs to 
depth accurately with solid ribs, especially the  tighter radii 
in the treble. With laminated, it's simple, accurate, and  more 
easily controllable.
  I admit it's tough to curve a 12 inch rib to a 20 ft.  radius & have 
thought about doing it differently



As far as performance goes once they're in the piano, I doubt  
there's much difference.
    Zzzzaaactly what I'm  thinking.
  Nice picture.  Says a lot
  Dale


Ron  N




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