Mason bearing quandry

[John Delacour]

At 10:59 am -0400 9/5/07, Erwinspiano at aol.com wrote:

>   On another note concerning the wooden gauges. I recently had a 
>1966 BB Mason & Hamilin.....  With no compression ridges or cracks & 
>only exposed to the beautiful CA climate for 40 yrs & with a church 
>building around it to buffer any humidity effects, this pianos belly 
>isÊpristine...

Hello Dale,

I read your message on returning from some experimentation and 
measuring of my current main project.  This is a piano that has lived 
in the glorious English climate for 140 years, for the last 12 of 
which it has been on its side unstrung in a breeze-block garage or a 
barn with no sort of climate or temperature control winter and 
summer.  I have two of these and the one in question is to receive an 
experimental soundboard, despite the fact that the original board is 
perfect in every way.

I did some rough measurements of the crown of this board this 
afternoon at each of the 12 ribs and discover that the average 
curvature has a radius of 45 feet and ranges from 60 feet at the 
central ribs to 20 feet at the outsides.  The underside of the ribs 
are perfectly straight, since it was established English practice to 
plane the ribs straight after the crown had been produced.

So far as I can tell there has been no deterioration of the condition 
of this board (or that of the piano's twin) in 140 years of neglect 
of anything to do with climate.

I shall soon be taking measurements from the twin, which is unstrung 
and still has the frame in to see what the angular deflections are. 
I rarely bother to measure these before I unstring a piano since they 
would normally tell me nothing very useful.

As to your M & H, I think I'd leave it as it is, as I think you will, 
unless you think awesome is not good enough! :-)

JD