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 **************Need a job? Find employment help in your area. (http://yellowpages.aol.com/search?query=employment_agencies&ncid=emlcntusyelp00000005) -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/caut_ptg.org/attachments/20090309/03b99b9c/attachment.html>
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