NY Steinway Ribs and MC

[Richard Brekne]

Hi Folks

Just got back from NY where I got the opportunity to do a long 
personalized tour of the factory.  As always one sees too much in too 
short a time to take it all in, but I had my eyes open for a couple 
special particulars.  When passing the rooms for soundboard and rib 
dry-down just prior to glue up I noted posted beside the doors the 
target MC for both.  So here is the absolute straight skinny.

Soundboards are dried to 3.8 to 4.5 % depending on the season. Ribs to 
8.6 %.  Both are put in their respective hotboxes for 3 days prior to 
glue up. The ribs are flat as we have been made to understand, and they 
glue them in shaped dish cauls (I saw glue up in the restoration room 
only f.o.s.) pressing the SB into shape and then ribs into resultant 
curves.  Bridges are cut to match the resultant curvature along its 
footprint by a computerized cutting machine.

This was very different from the Hamburg process. Hamburg did not use 
dished cauls do begin with, but individual cauls for each rib length.  
Nor did they have a dry down room for either prior to glue up.

I'm unsure of to what degree using dished cauls will affect the after 
glue up shape. Straining the panel in directions other then 
perpendicular to the grain before glue up ?? Have to think about that one :)

Anyways... this stands in contrast to the post I have referred to 
previously from John Patton I am unsure of why. It may be that they have 
some short waiting period between removing the panel and ribs from their 
respective hotboxes before actually gluing them together.  The rooms are 
quite warm and wood inside as well. Perhaps they need at least to let 
everything cool just a bit ?  The person guiding me was unsure of that 
answer and we didn't get the chance to confirm one way or the other.

Cheers
RicB