In an earlier post in the friction thread, I described a device I had imagined to measure the weight of the damper as felt at the key. I had a little time to spare between access to rooms, and put one together. I think it took me all of ten minutes. A base about 1x4x8", a "balance rail" scrap of 1/2" plywood, a lever about 2' long, 1/2 x 3/4" (I think scrap from a strip used to hold hammers in place during shipping), a couple pedal brackets, a standard .146" balance pin. I glued a little scrap of wood on one end of the lever as a platform for weights - not really necessary, but nice - and then drilled a hole in the lever at the balance point. A couple drywall screws to hold the brackets, driven in with an electric screwdriver. It works very nicely. I tried it out just to see what I'd find, and a couple things jumped out at me. First, there is quite a bit of force needed to push trichord dampers out of the strings - as much a 5 gm. Even when trimmed nicely and precisely to the bottom of the strings there is a significant amount, though the difference between well- trimmed and not trimmed is noticeable, also between well-trimmed and just shy of well-trimmed (0.5 mm below the string line). On the concert instrument, where I have taken a fair amount of trouble to have the dampers well-regulated in all ways, I found a range from about 20 gm to over 30 gm top to bottom, and some zigzagging along the way in the 5 gm range. On a B that I had replaced action parts and damper felts on, but had only slapped the dampers in and regulated them for lift and to be sure they damped (fine-tuning put off until time allowed), I found much larger zigzags, 10 gms from one to its neighbor in a quick sampling. I suspect a lot of it had to do with some wires leaning on bushings, others not, but won't know until I have time to look more carefully. Bottom line, I think this is a good thing to look at, a significant element in the touch of a grand. PC100011.JPG PC100015.JPG PC100017.JPG Regards, Fred Sturm University of New Mexico fssturm at unm.edu -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/caut.php/attachments/20101210/9249e88a/attachment-0001.htm> -------------- next part -------------- A non-text attachment was scrubbed... Name: PC100011.jpg Type: image/jpeg Size: 20364 bytes Desc: not available URL: <http://ptg.org/pipermail/caut.php/attachments/20101210/9249e88a/attachment-0003.jpg> -------------- next part -------------- A non-text attachment was scrubbed... Name: PC100015.jpg Type: image/jpeg Size: 19209 bytes Desc: not available URL: <http://ptg.org/pipermail/caut.php/attachments/20101210/9249e88a/attachment-0004.jpg> -------------- next part -------------- A non-text attachment was scrubbed... Name: PC100017.jpg Type: image/jpeg Size: 18864 bytes Desc: not available URL: <http://ptg.org/pipermail/caut.php/attachments/20101210/9249e88a/attachment-0005.jpg>
This PTG archive page provided courtesy of Moy Piano Service, LLC