[pianotech] Reversing Crown

[Noah Frere]

I find this confusing because I would have assumed that as soon as the
soundboard starts pulling away from the strings, and negative bearing sets
in, then the strings would be *pushing* the soundboard down further, rather
than pulling up. I imagine it this way: imagine a tunpperware container with
a lid that's slightly convex - you push the sides together and it forces the
lid up higher. (the equivalent of putting on strings). Now take the pressure
off the container and push the lid down just enough to make it concave,
reapply pressure, and the lid will continue its downward path.
   Visually this description reminds us of the soundboard, but i mean to
apply it to downbearing. That is, no matter which direction the crown is
facing, the tupperware lid represents the board/bridges as a whole.
   However, being neither a physicist nor a rebuilder, i must have it wrong,

On Thu, Dec 31, 2009 at 1:06 AM, David Love <davidlovepianos at comcast.net>wrote:

>  That’s right.  Anytime you have negative bearing, the strings are pulling
> the bridge up just as with positive bearing they are pushing the bridge
> down.  If you were to detach the strings from the bridge pins where there
> was negative bearing they would hover above the bridge.  You would have to
> push the string down to reattach it to the bridge thus the force from the
> string would be upward.
>
>
>
> David Love
>
> www.davidlovepianos.com
>
>
>
> *From:* pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] *On
> Behalf Of *Noah Frere
> *Sent:* Wednesday, December 30, 2009 9:14 PM
>
> *To:* pianotech at ptg.org
> *Subject:* Re: [pianotech] Reversing Crown
>
>
>
> Sounds good. I don't understand this though: "that means that the bridge
> is being *pulled up* by the strings" in the second case. It was my
> understanding that negative bearing means the bridge is lower than it should
> be, causing the strings to be slightly v-shaped rather than ^-shaped.
>
>
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