Seating strings

[Ron Nossaman]

>> Spitfire propeller blades! I'd love a sample if the hacksaw survives.
> 
> 
> OK.  I'll give it a shot, assuming I can locate the sample.  If the 
> hacksaw doesn't work I'll fire up the laser cutter.

I'll round you up a sample of my veneer lamination and we can 
exchange prisoners.


> I agree that downbearing couldn't crush the notch edge past the point 
> where the string is making contact with it.  I also agree that the 
> damage is (mostly) not being done by downbearing.  It's being done as 
> the cap moves up and the string doesn't.  Let's remove the pins and the 
> notch.  The bridge is now a square block of wood.  Run a stiff string 
> over it so that it's coming off the square block at a 1.5 degree angle 
> on both sides.  What are you going to see?  The string will be 
> contacting the block at the edges and up in the air in between.  The 
> bearing stress at those contact points is going to be very high. 

But not nearly as high as what the pins produce. Yes, I understand 
the thinking here, but I don't think rounding the bridge top will 
provide a benefit. First: how do you determine the proper curve for 
the tangent? Oops, a bit too deep! Second: how do you practically 
produce this curve in a step notched bridge? Third: By curving the 
top, you have eliminated the "pad" that the cyclic crushing from pin 
friction had before the notch edge is below tangent. I see it 
producing false beats quicker than ever.


  >Even if the top of the bridge was curved the string
> may get crushed down into the cap in the vicinity of the pin, as you 
> say.  

I don't see what would prevent it with a humidity reactive cap.


>I'm inclined to think that moving the notch back away from the pin 
> might make this crushing a little less.

I expect that's right, and if the pin could be kept solid in the cap 
at the top, it would remain a clean termination.

Ron N