[CAUT] String Leveling question

Sloane, Benjamin (sloaneba) sloaneba at ucmail.uc.edu
Mon Mar 9 07:00:16 PDT 2009


    Hello all,
   Dampers? Una corda? I think both these are why we level strings, not the hammer. If we leveled strings because of the hammers, we wouldn't bother with a leveling gauge at all. We would just bend the strings to mate with the hammers in the first place, if the hammers didn't move sideways (i.e.,  when engaging the soft pedal, not a loose shank action center). The advantage of having strings plum to the keybed, plate, or whatever we use to determine what level is, arises when employing the una corda. Doing this can both ameliorate and exacerbate damper performance.

-          Ben

From: caut-bounces at ptg.org [mailto:caut-bounces at ptg.org] On Behalf Of McNeilTom at aol.com
Sent: Monday, March 09, 2009 7:46 AM
To: caut at ptg.org
Subject: Re: [CAUT] String Leveling question

Hi, David and Colleagues -

I have little to add to Fred Sturm's very thorough reply on this topic.  Here's the 'little'.

It's impractical to use the plate as the reference base for leveling anything since most of its surfaces are not flat and the whole casting is subject to irregularities.  The keybed is a decent reference plane since it's fairly flat, and - on the blueprint anyway - level with the earth.  In most modern pianos the string plane is designed parallel to the keybed.  (Actually, there are two string planes of course counting the separate one for the bass strings.)  However, various things happen in the execution of the blueprints conspiring in most cases to leave the string plane not perfectly parallel to the keybed.

A practical solution is to use the actual plane of the strings as the reference plane.  When I'm trying to do string leveling as well as I can, I use a level placed along the strike line of a whole section.  Then I level that line by jacking up the piano at the treble or bass leg as necessary.  Even this is an approximation because of all the irregularities of the string thickness, etc.  But if the strike line is leveled like this it enables you to get more 'information' from the bubble on the Goss tool.

As Fred has pointed out, the goal isn't really 'levelness' in the strict sense; it's just to get the hammer to strike all its strings simultaneously.  The string leveling changes slightly when the strings move around in the course of tuning.  This can be significant with a new or newly strung piano during the "mostly pitch raising" tuning phase.  Good to tweak the leveling again after some months of tuning and playing.

~ Tom McNeil ~

Vermont Piano Restorations
346 Camp Street
Barre, VT 05641
802-476-7072

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