Blüthner Technika - Drewniana Konstrukcja Nośna

 
 
The back

The back has to withstand the high tensile forces of the strings who mount up to 20 tons. The iron frame adds tro the necessary resistance. The soundboard it firmly fixed between the back and the iron frame. Rails made of hard red beech are used that respond exactly to the crown of the sound board. It is glued onto strips of red beech, which correspond precisely with the crown of the sound board. These heavy parts rather reflect the vibrations of the strings onto the sound board them moving self.

The essential part of the back is the inner rim which is bend in a press out of 18 layers of hard red beech veneer. Later the outer rim is glued on so that the complete case is made of 28 layers of veneer.

The tensile forces of the strings are taken up by strong bracings that stem against the cross bar. They are made of a lamination of solid beech in the middle and pine on the outside. They are then dovetailed into their bedding. The red beech lamination later ensures a tight fit of the plate bolts for the iron frame. This construction ensures a long lasting stability under high tensile forces.