Hello List, I am sure this is old stuff for those of you who design soundboards, but I will post it anyway. I often wondered about methods of measuring soundboard thickness, once the board is installed. I was in a violin shop today and saw how violin makers do it. The tool is so elegant and simple! It consists of a small magnet and a spring loaded tool that visually resembles a long syringe. I have no idea what this tool is called, so I will just call it "syringe". Inside the syringe is a spring, one end of it attached to an iron disk (or possibly another magnet). The other end of the spring is attached to a handle that sticks out of the syringe. The function of the syringe is to contain the spring and it has a calibration scale on it as well. The magnet goes inside the violin body. The syringe is on the top. The little magnet is attracted to the iron disk in the syringe and the attracting force is related to the thickness of the intervening wood. When you pull on the spring, it stretches and eventually the force from the spring is approximately equal to the attracting force between the iron disk and the magnet. At that point, the magnet drops and you hear the impact. On the calibration scale on the syringe, you can read off how thick the wood was at that spot. Then, you let the spring retract, the iron disk is near the violin top again, and if you move the violin body, the magnet finds the plate again. You can slide the tool over the top and map out the thickness. Vladan __________________________________ Yahoo! Mail - PC Magazine Editors' Choice 2005 http://mail.yahoo.com
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