Bridge pin angles

[Ron Nossaman]

> Thinking some more about bridge notch crushing.  Aside from making the cap 
> from some impenetrable substance, one way to reduce bearing stress at the 
> notch edge would be to reduce resistance to the upward movement of the 
> string.  This could be done by reducing side bearing angle and bridge pin 
> angle.  If there was no side offset at all and the pin was straight up and 
> down then it could easily slide as the bridge moved and the downbearing 
> would be enough to keep it seated on the bridge at all times.  Of course, 
> it wouldn't sound too good.  I wonder what lower limits would be?  Has 
> anyone experimented with this.  I would think that establishing minimum 
> sidebearing angle would be something that some piano company has worked 
> on.  Is anyone aware of any numbers?  Bridge pin angle is something that 
> seems less obvious as an item of investigation, but perhaps work has been 
> done on that too.  Anyone know of anything?
> 
> Phil Ford

Nothing pertaining to published data, but I have (oddly enough) some 
thoughts on the matter. As often as I've found zero or negative 
bearing in the killer octave through the years, I have little to no 
remaining faith in downbearing being a reliable given. If we can't 
yet easily go to a vertical bearing offset from available bridge 
agraffes, we can at least try to make the existing slanted pin 
string offset system more reliable. Along those lines, reducing 
offset angle and/or pin angle will only reduce the quality of 
termination. Personally, I'm not too enthusiastic about determining 
the minimal tolerance here, because it would be very likely to 
become the standard. I'm a belt and suspenders kind of guy (with 
thanks to Justin Wilson for the concept). I want a built in 
tolerance pad. I'd rather attack from a different direction than 
surrender quietly. That being the case, I prefer 20° pin slant to 
15°, and 10° offset to 8°. The price for better clamping termination 
from these angles is paid in cap PSI loading and resultant 
deterioration. Given the choice of backing off on the termination 
quality to accommodate the traditional delicate capping material, or 
providing both a robust termination clamp, and a cap that can take 
the PSI levels, I'll work toward the latter. There's a lot of 
unexplored territory in this direction.

Ron N