Hi Del It would seem to me that raising tension or not on an older instrument has a natural structual limit of safety. As long as you hold yourself safely within these boundries I would think one should feel free to do what one wants. I am in the middle of an old instrument rebuilding at this time also. The instrument shows absolutely no sign of pinblock stress from overloading. No roll, or flexing of the area we'd usually call the stretcher. Nor do I find any real sign of structural strain in the rim and bracing. This thing had a total of just over 13000 kilos tension if modern string specs are used to figure tension. Roughly 29000 lbs. I'm probably going to increase that slightly to about 14000 kilos and most of the increase will be coming at the top of the scale. The present top note #85 is at 48 mm long and it will probably end up around 50.5-51. Most of the top octave will increase slightly, and a few scattered notes to even out some humps here and there. This is also getting a new soundboard and design. The basic design is the same, but I've introduced some crown into the system using a 3 ply laminate setup in which crown was establised as part of the lamination process. Otherwise.... the thing remains very close to the origional. I'm doing a bit of experimenting with ideas here to be sure... but essentially I'm hoping to give it a slightly more modern treble that gradually moves towards the original bass sound (which I have always liked). The middle ply is thinned so as to take care of the original thinning of the soundboard as a whole. This also very gradually lessens the crown and crown strength I've introduced into the treble. With this I hope to be able to also introduce a bit of downbearing in the upper regions of the scale. More then likely the thing was pretty much strung without any downbearing at all. The original rib orientation would offer little support thus. So a tad more tension... a bit more downbearing coupled with a bit more stiffness and strength from a panel that shows a non-linear spring rate... Well... we'll see how it turns out. Cheers RicB I'm remanufacturing one of the early Type I (85-note, 8' 5") grands right now. There was no sign of stretcher/pinblock structural failure. In this case the customer and I opted to install a pair of pinblock inserts rather than remove the whole assembly and build up a complete new pinblock assembly. I'm still debating whether or not to install some type of gap-spacer to help carry the load. Once I get the major action parts installed and back in the case I'll see how much room is available and decide at that time. This instrument is getting a complete redesign--new soundboard & rib design, new bridges, new scale, new action, etc.--and, based on previous work on these instruments, I'm confident the results will be worthwhile. A caution is in order here: These pianos originally had relatively low-tensioned string scales and they should stay that way. I'm actually removing some tension from the scale of the piano I'm currently doing. The piano now has a new tenor/treble bridge and a log scale. As a result a significant hump in the middle of the tenor section has been smoothed out. No attempt should be made to make these pianos into modern powerhouse instruments. Properly redesigned and rebuild they are wonderful pianofortes. They cannot be made into fortes. Del
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