[CAUT] left to right or R to L?

[Fred Sturm]

On Nov 14, 2008, at 10:03 AM, Ron Nossaman wrote:

> Fred, it's not an indication of anything at all useful, and using it  
> as an indicator of where to set plate height will likely guarantee  
> you'll screw it up. Vertical hitches, also, have not a thing to do  
> with it. It's a simple matter of how much the board will deflect  
> under load at the final bearing angle, vs how much initial unloaded  
> crown.
Hi Ron,
	This exchange has been largely a matter of arguing at cross purposes.  
Yes, you are right, precisely, the question is how much initial  
unloaded crown versus deflection under load. When you are getting  
ready to string, one thing you have available to look at is deflection  
before load. It makes sense (at least to me) to take a last look at  
that before putting on the first string. If that deflection is around  
8 mm at the top strut (that crosses the bridge), 15 mm at the next, 20  
at the tenor, I, personally, am going to raise my eyebrows and spend  
at least a bit of time reconsidering before plunging ahead.  
(Deflection at this point being measured with a taut string from front  
bearing crossing the bridge, then measuring down to the string rest).
	And that is pretty darned close to what there would be if bridges  
were touching struts on most pianos I have seen that I would be likely  
to put a new board in. So, no, of course distance from the strut to  
the bridge is not a good indicator of where to set plate height. But a  
rough observation that the bridges are at strut level might be enough  
to make one think twice before proceeding, just like a piano well over  
100 cents flat will prompt one to look for possible structural problems.
	That is absolutely all I was saying (or at any rate meaning to  
convey) initially, or at any point later in the conversation when  
talking about strut and bridge relationship. I doubt very much that  
it's a point worth arguing about.
	On the question of wedging down a board to emulate load, I am not at  
all convinced that that procedure gives enough or correct information.  
Too rough for my taste, though I know there are people who do it and  
claim to be successful. The fact that usually "it goes back to very  
near that same position" under string load isn't enough for me - but  
that gets into some fairly complex things I don't really want to get  
into here. And I still think EMC should be taken into account.
	I have gone on enough (or too much) on the topic, so I'll leave it  
there. You're welcome to have the last word.
Regards,
Fred Sturm
University of New Mexico
fssturm at unm.edu