Bridge pin angles

[Phillip Ford]

>
>
>The point is that we can't assume downbearing, so we angle and 
>offset pins to provide a positive termination that's largely 
>independent of bearing.

If we're a factory cranking out pianos using construction methods 
that don't guarantee downbearing or using a design that doesn't 
insure downbearing long term, then we better have lots of insurance. 
I thought the point of these endless discussions about rib crowned 
boards, laminated ribs, proper rib size for bearing load applied, 
etc. was for us as rebuilders to arrive at a point where we're doing 
what we're claiming the factories are not doing.  Designing and 
building a board that's structurally adequate for the load applied, 
insuring that it has the bearing load intended when it leaves the 
shop, and is going to stay that way long term.  If we're 
accomplishing this then I don't see that we need the levels of 
insurance of said factory.

>  If the above piano had 15°-20° angled front bridge pins in that 
>problem unison, the only tonal problem would have been the generally 
>nasty distortion at higher attack levels in the killer octave that 
>everyone is so used to hearing that they don't even notice, and 
>everyone would have been happy. What I'm interested in is a standard 
>of offset and pin angle that will reliably provide that termination. 
>I'm not particularly interested in establishing minimum tolerances, 
>because I don't wish to build to minimum tolerance, and these 
>tolerances can't be accurately established anyway. There are too 
>many variables.
>
>Ron N

Establishing a minimum and building to it are two different things. 
I'd like to know what the minimums are.  If what is needed for the 
termination to function properly with a properly set up and properly 
functioning board is 2 degrees of side bearing and a bridge pin angle 
of 5 degrees then I don't want to put on 10 degrees of side bearing 
and a 20 degree pin angle just to be safe, because there are negative 
consequences for doing so, in the form of poorer rendering and 
increased bridge cap wear.

Phil F