[pianotech] Soundboard Analysis

[William Monroe]

Hi Will,

One issue I have with the Crownulator is that boards do not necessarily
(necessarily don't?) crown in a nice even radius.  Rather, they tend to be
variably crowned.  I doubt that's news to you, so I'm posing this more as a
question of whether or not you are comfortable with that limitation, and
with working around it using Jude's gauge.  I'm sure you've probably taken
readings at various placements along a particular rib  - what does that tell
you?

Thanks for the insight.

William R. Monroe



On Wed, Jun 22, 2011 at 7:17 PM, Encore Pianos
<encorepianos at metrocast.net>wrote:

> Hi David:****
>
> ** **
>
> I’m going to throw in my 1 ½ cents here for what it’s worth to you and
> others.  I do some things a little different than you do.****
>
> ** **
>
> Let me start by saying that I think there are better ways to measure crown
> than the method you describe.  I used to measure by way of the string method
> more or less as you do.  It’s slow, awkward, and probably not terribly
> precise.  ****
>
> ** **
>
> About a year ago, I bought a Crownulator from Jude Reveley.  It is made up
> of a 1 ‘ long steel bar accurately flattened on one side.  In its center is
> a hole through which passes the moveable foot of a dial gauge.  You lay the
> bar square on the panel next to the rib.  As long as there is positive
> bearing, the dial gauge foot will move a distance that will be measured on
> the dial.  It’s a mirror image reading, so if the gauge is reading .080 (of
> a full circle of .100), this means that you have .020 of crown over that 1’
> span.  There is a formula by which you can drop the numbers in and calculate
> the crown for the rib.****
>
> ** **
>
> I use it when putting in new boards too.  After the board is glued in and
> otherwise ready to go for stringing, I take a crown reading on as many ribs
> as I can get at and record those measurements.  When setting bearing, drive
> the board down and take crown readings til I get my target of 50%
> deflection.  Record those measures.  Then string and tune the piano, measure
> crown again and see how well I guessed in the process****
>
> ** **
>
> I think you would find the Crownulator significantly more accurate,
> quicker, and far easier to use.  ****
>
> SNIP
>
> Will Truitt****
>
> ** **
>
>
>
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