Do you dry the ribs, along with the board, prior to gluing ?

[Richard Brekne]

Rib extenders are simply additions to the height of the existing ribs.  
They can be made with some degree of machined crown so that when glued 
they exert an upwards force on the existing assembly.  One can also put 
them in a high humidity hotbox and glue them on in a state of very high 
MC so as to attempt to take advantage of  their shrinkage as they loose 
MC... kind of the reverse of gluing a dried panel on the board.  That 
last came to me from Ron Overs recently.  I suppose you could press the 
assembly upwards as well and glue on extenders match the surface of the 
existing ribs... also a way of increasing crown.

The point with extenders as I understand it is that they increase 
existing rib height... which does a lot more for stiffness without 
adding as much mass as adding extra ribs will.  Of course you have to 
have room to place them... and if you are dealing with very high ribs to 
begin with then perhaps this is not such a good idea.  But for shallow 
and wide ribs that have lost their gumption.... seems like a good idea.

Cheers
RicB

    "Rib Extenders "??? What's that ???  This one has wide, flat topped
    ribs,. so I thought I might laminate something ( suggestions as per
    materials appreciated ) to their tops, if I'm not happy with the
    crown I get.  I'll tell you all about this recrowning method when
    I'm done, and have more to report per results.

        Peace,
         Thump