Ron Nossaman wrote: > >> During the wet cycle, > > > >This sounds great.. could even be exactly whats happening. Or it could be just > >a compounding factor. > > Could be, but I did run an experiment that showed me the bridge surface > does move up and down the pins with MC changes in the bridge. How about > doing us one to measure the up force necessary to push a string under, say > the usual arbitrarily chosen 160lbs tension about 0.010" up a pair of > bridge pins against 1° downbearing, 10° pin stagger angle, and 20° > inclination angle. If it's over 1470psi, we'll have a winner. If not, we'll > be back where we started. > I have no doubt that the bridge is moving, what I questioned was whether this was the reason (or how much of the reason) for the string indentations. As I said, with positive down bearing it would seem to me the same indentations would come about anyways. Grin... I suppose you wouldnt mind explaining the significance of 1470 psi here...:) If you get a chance you might describe your experiment a bit for us. > > >Heres the other point that makes me scratch my head....xxx the question > this fact raises is > >why doesnt the string conform to the somewhat rounded profile of the bridge ? > > Depends on the overall downbearing angle, doesn't it? As the board sinks > and bearing approaches zero, what happens? > > > >and why then the same string under the same conditions "bend" nicely over the > >bridge if you simply remove the bridge pins ? > > Does it, or is this just speculation? as long as we have enough positive downbearing.. I cant see how it could escape from doing so. But I will certainly buy that if there exists a point on the bridge that is lower then a line drawn between the maximum deflection and the termination points, then forcing the string down at this point will most definitly create the problem you described... > > > > I would think that you would have > >to have a point on the bridge near the edges that was below the level of the > >front temination point, or the bearing point behind the bridge in order to > >create what you describe above. > > Exactly the point. I think I see your point well enough. As I understand it thats the basic reasoning behind seating pins by tapping lightly between the pins. Whatever seating is needed and / or benificial will be taken care of in this manner. Pressing or tapping outside the bridgepins risks damaging the bridge as well as quite possibly creating this temporary situation you describe. I still see a need to seat strings on bridges tho... but I dont really think the reasons for this are at odds with your points here. > >I wonder also if you could explain what you mean by > >"behind the (-20°) vertical. > > The bridge surface is the horizontal termination, the pin is the vertical, > only it's not vertical. Any way I could possibly have said this would have > been challenged by somebody, so I went for literal. I wasnt really challanging it... just didnt quite get your meaning. Still unclear as to how this in itself can cause a false beat, if thats what you were saying. > > Ron N What would happen I wonder if you took oversized bridgepins, and notched them purposely to hold the string in place vertically....grin.. -- Richard Brekne RPT, N.P.T.F. Bergen, Norway mailto:rbrekne@broadpark.no
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