Cents=Lbs

[Ron Nossaman]

><< On that S&S D I posted tension figures on, it made 18 lb difference between
> 435 and 440. In a piano less heavily loaded with bearing than this one was
> in the treble (2.4°), it would be less. Maybe it would be better to let
> this one go, I don't think it would impress them all that much. <G>
> 
> Ron N
>  >>
>
>If a 5 cent increase in tension resulted in 18 lb. of addition down bearing, 
>would a 50 cent increase be 10 times that much, or 180 lb.? And would a 100 
>cent increase result in a 360 lb. increase? If so, is that impressive enough 
>for a customer? Since they have nothing to compare that to, maybe it 
>wouldn't. What do you think?
>
>Willem 

Hi Wim,
Not a 5 cent increase, a five cps increase = 20 cents increase = 18 lbs.
That's 0.9 lbs per cent. My spread sheet shows a semitone increase from A-4
= 415cps@704 lbs to A-4=440cps @792 lb. This isn't exactly accurate though,
because there's no allowance for the fact the bearing angle decreases as
the board is loaded, so the bearing actually increases in a diminishing
progression with tension, rather than in a linear fashion. I considered
trying to build it in, but it got too complicated for the importance of the
information obtained, so I didn't attempt it. So with a roughly 18 lb
bearing increase with 20 cents pitch increase, you'd be looking at probably
under 75 lbs bearing increase with a full semitone pitch raise to 440. The
tension increase is still lots scarier.

Ron N