[pianotech] Measuring Crown Radius

[Ron Nossaman]

On 7/12/2011 2:06 AM, David Love wrote:

> BTW there’s a good article on this particular subject in the February
> 1984 PTJ written by Bob Hohf.

That's the one! When Jude's crownulator was mentioned recently, I 
thought of this article,but didn't find it.


> On an unloaded board, what would be the minimum amount of crown you’d be
> willing to work with and why?

In the many instances of trying to diagnose soundboard problems in 
pianos, nearly everyone, certainly every manufacturer's rep, has told me 
you can't tell the condition of a soundboard under string load. I find 
this to be entirely backward. An unloaded board will tell me virtually 
nothing about it's load capacity, while a board with positive bearing 
load retaining positive crown is an indication of a structurally viable 
board. Anything an unloaded board seems to be telling you is untrustworthy.
Ron N