Geoff Sykes wrote: > It's so easy to get into arguments on the list. This is about what's fact and what isn't. > Screws imbedded into metal rarely need tightening unless they are subject to > vibration. And even then the phenomena is rare. That's because metal changes > very little with changes in temperature or humidity. Right, which is why perimeter bolts in Baldwin and Yamaha grand don't move when checked for tightness. >Wood, on the other > hand, can change quite dramatically with changes in temperature and > humidity. Why do you think a piano can go out of tune simply by turning on > some stage lights? Because the hot lights expand the strings, that's why. It's not wood movement. >Over time, things like screws, nails etc., will be > effectively squeezed out. They get loose. They need to be tightened. I understand how they get loose. I'm questioning the "need" to tighten them periodically when they'll just get loose again as more wood is crushed. It seems to me that stability would be better served by letting the system settle where it will after a first "service bond" type procedure after manufacture, and reach equilibrium. Thirty years ago, I tuned a lot of old uprights. Someone had mentioned to me that the washers under the plate lag heads across the top were worth notice. If they could be turned by hand (the washers, mind you, not the bolts) it was an indication that the back was still solid. Many of these old pianos with "loose" bolts were as stable as anything I've seen since. So the question remains. Why is it necessary to periodically tighten plate bolts when there is no clear indication that tuning stability is enhanced by the process, while there is every indication that increasing damage is being done as a result of periodic tightening? Ron N
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