Perhaps I expressed myself badly. I didn't mean to imply that there is a direct correlation between pin angle and stagger angle. However, if the pin angle, or the offset of the string caused by a greater pin angle, is causing cracking of the bridge, then the designer who wants to use a greater pin angle could compensate for this tendency to crack the bridge by deliberately creating less stagger angle by moving the bridge pin holes relative to one another. If one saw a piano with a large bridge pin angle that did have this compensation and there was no cracking it might not be correct to assume that a large pin angle has no effect on bridge cracking. However, if things are as you say, that other factors have more influence, then excessive pin angle probably doesn't matter to a sound bridge. Phil --- Phillip Ford Piano Service & Restoration 1777 Yosemite Ave San Francisco, CA 94124 On Wed, 05 Sep 2001 22:48:01 Ron Nossaman wrote: >>Ron, >>The bridge pin angle seems to be about 25 degrees. I take it from your >>response that you've seen other pianos with angles this much or more >>that don't have cracking problems. > >Since I'm as mortal as can be expected under the circumstances, I haven't >seen all possible configurations of anything, much less everything. With >that in mind, the bridge failures I've seen through the years have seemed >to me to be more related to the grain angle relative to the bridge root, >and/or the degree of quartersawnedness of the cap, than to the excessive >draft angle of the bridge pin. If "quartersawdness" proves on examination >not to be a real word, I can only take the "look and feel" plea in defense. >My grasp of the language does occasionally fail me. A less than adequate >angle does, however, present a rather dramatic set of tonal problems when >the front bearing angle is inadequate. > > >>This is also tied in with where the >>bridge pins are located relative to each other. If the back holes are >>directly behind the front holes with a 25 degree pin angle then you'll have >>more load on the pins than if the holes are slightly offset from one >>another with the 25 degree angle. On this piano the back bridge pin >>holes appear to be directly behind (in line) with the front bridge pin >>holes. >> >>Phil > >Well now, this is another thing altogether. The relationship of the pin >angle to the stagger angle isn't a direct correlation. Both the pin angle >and the stagger angle are individually and rather easily determinable >before a hole is drilled in the bridge top. One isn't in any way determined >by the other unless the bridge architect is operating by rumor, innuendo, >dumb luck, what he thought he overheard in the bar at the Cleveland >convention, or horoscope - status quo to the contrary. It's really not >random chance in practice, and ain't that hard to figger. > > >Ron N > Get 250 color business cards for FREE! http://businesscards.lycos.com/vp/fastpath/
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