Back in 1985I asked Michael Walker how he thickness-ed his Walter copies he said 3.8 for the bass 2.8 for the treble. I have generally stuck with these values for my Walters and I have been pleased with the tone. I don't know if he had actual measurements. I think 4mm is too thick your Walter will sound like a Broadwood I think generally Viennese makers kept their soundboards on the thinnish side even up to the 6 octave instruments often not much thicker than harpsichords. I will post some measurements from my other drawings shortly.

Richard

::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
Note:  opinions  expressed on HPSCHD-L are those of the  individual con-
tributors and not necessarily  those of the list owners  nor of the Uni-
versity of Iowa.  For a brief  summary of list  commands, send mail to
[log in to unmask]  saying  HELP .
::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::