laminated ribs

[Overs Pianos]

Hi Ron, Terry and all,

>>I'm with you on ease of crowning, accuracy and more uniform 
>>statistical average MOE from batch to batch. But why would a 
>>laminated beam have a higher average MOE than a similar solid beam?
>>
>>Terry Farrell
>
>
>I'm not sure, but they seem to. I tested this once and recall 
>finding that to be the case, but it's been a while so I might be 
>mistaken. Memory leaks, and such.  Maybe it's time to do it again.
>
>Ron N


No Ron you're not mistaken. Laminated beams have a higher MOE. 
Relative to a solid beam, the internal stresses which occur naturally 
in the growing tree are largely dissipated when the individual layers 
are joined back to form a whole.

One only has to watch sawn strips warping all over the place as they 
come off the saw to realise what must be going on inside the full 
piece prior to resawing.

Think a tug-of-war analogy. With five strong people of nearly of 
equal strength, at either end of a rope, it will only take a small 
addition plus or minus to topple the balance in one direction. If 
those five strong people were all working together holding a bar 
firm, for example, it would take much more than a small force to move 
the bar.

Similarly, the various sectors of wood in a solid beam are not acting 
to support a given load. Some will be trying to move with the load 
while other sectors will be supporting it. If a similarly dimensioned 
laminated beam was used to resist a load a much higher proportion of 
the beam will be working to support the load. Hence the higher MOE in 
the laminated beam. Hope that makes sense.

Ron O.

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OVERS PIANOS - SYDNEY
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