>> 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
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