Noah Frere wrote: > I am trying to measure crown in this 1906 Spector & Sons Baby Grand. > When I run a string, 1/32" diameter, along the length of the 7th of 10 > ribs (counting from the front treble area towards the back), underneath > the soundboard, I see noticeable crown (Picture 8852). I'd call that rib #3, with rib #1 being in the low bass and the last rib being in the treble - like the strings, so there's some procedural continuity in nomenclature. >I got similar results along most of the ribs. My method was to tape one end of the > string at the edge of the soundboard and hold a chopstick to which the > other end of the string was glued. The method's fine. How far up did you measure into the treble? Rib #3, which is where most techs' measurements start and stop, is just about the least informative you can make. How was the crown up in the killer octave, and as far into the treble as you could reach? How was the bearing relative to the crown at each measured location? > When I use a short straightedge, there is very little gap (Photo 8875), > which I expected. A short straightedge is generally useless. You need rim to rim to get a good look at what you have. > Above the soundboard, That's enough. There are no reliable or informative measurements you can take from the top of the board that will tell you anything useful. Is the board thinned at the edges? How much? > Anther questions: is the string too thick? You can see it in the > "crown-string" picture. No. As long as you can see it, and see past it to it's shadow, it'll work. > Does all this points to an undulating soundboard? No more than it indicates elephants. If there was any evidence of an undulating soundboard, you could see it from underneath with your string - rim to rim. Bats are something else... Ron N
This PTG archive page provided courtesy of Moy Piano Service, LLC