On 8/12/2010 6:08 AM, William Truitt wrote: > > Hi Jim: > > Thanks for the thoroughness of your reply. Well, ain't I the numby > dummy! I didn't take note of the arrows, and assumed that if the > reading was negative, there would be a minus sign in front of the > number value. (That assuming can sure get me in a lot of trouble). > In my own feeble defense, there is nothing in the directions indicate > what the arrows mean, at least not the ones I got. So chuck my > readings out the window for now. I was wondering why I had no > negative readings, particularly on that old B board > the arrows tricked me the first time I used it too. > Regarding the composite angle you describe, I assume from what you > write that the only thing you are measuring is the difference, > positive or negative, between the front and rear bearing. Yes? > yes > > I have long read that the bearing angle should be between about .5 > degree and 1.5 degrees, depending on where you are in the piano. I > don't want to assume anything again, so I will ask the question -- > does the value you record using this method correspond directly to the > values just given (and which I believe are a component reading)? > yes > > > To get the composite reading, don't you simply add the front and rear > angles and divide by two to average and get the proper value for the > bearing angles? > ugh...no...now I see why you were trying to find some reliable reference to work off of...this will just complicate your life immeasurably, help you to make mistakes, and give a reading that has no practical value, ie doesn't mean anything. The way I described using it uses the device as an indicator to determine composite angle by simply noting the difference between front and back angles. > > The up and down arrows as described in your list (thanks) have meaning > only in relation to the zero point, and are not in and of themselves > an indicator of positive and negative bearing. > thats right As a side note on downbearing, as an experimenting belly designer myself (getting better too, I must say, yay), you might find it useful to intellectually chuck everything you knew, or thought you knew about downbearing and start fresh in your thinking, especially in an rc&s design (if that's where you are going). Reading through trad approached to determining and setting downbearing will just take you down confusing dead ends, as rc&s vs cc behavior is not apples to apples in this regard. The composite angle gives you (individual string lbs bearing= sine of composite angle x individual string tension) a way to determine how much load the board has to carry...thats all thats of practical use...at least thats the way I'm using this measurement. For example, I really don't know what practical value the measurements you are taking on the old B have, other than to maybe help you decide the elevation of the plate or something. Seems like it would be useful to see in a very general sense where the board failed, but past that, it would get you thinking apples to oranges and just confuse your new design thought right from the beginning...no? Jim I -- Jim Ialeggio grandpianosolutions.com 978- 425-9026 Shirley, MA -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/pianotech.php/attachments/20100812/8059db07/attachment.htm>
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