Component Downbearing Gauge Measurements

[Ron Nossaman]

Thanks Tom, that's what I needed, mystery #17,928.5 cleared right up. My
crude shop measurement was 1/3 degree off for 16 divisions. This makes more
sense. Nice tool, I've found it pretty handy, even with the wrong numbers. 

Anybody want an *updated* Baldwin/Lowell degree/bearing chart? 

Ron


>First I must apologize on behlaf of Pianotek for their not including the
>instructions
>to the Lowell Component Downbearing gauge.  Please  call them and request the
>instructions, or if they are out, E-mail me back and I will send you some.
>
>In brief, the thousandths of an inch quantities represented by the linear
>increments
>(division lines) on the gauge are the rise or fall (vertical dimeansion) per
>inch of
>length of piano string.  So, to give an example, if your rear string length
>was
>3" and your gauge measurement was .009", then the difference in elevation
>between
>the top the the bridge (a reference at zero), and the rear string rest would
>be 3" x .009" or .027".  Very simple math.  These dimeansions can be converted
>to degrees of angle by multiplying 1/6 degree times the number of division
>lines the bubbble has crossed.  Crossing six division lines would mean 1 full
>degree of string angle.  More simple math.  To determine the lbs. pressure
>from the net downbearing measurement multiply the net bearing in thousandths
>of an inch by the tension of  the string.  For example, a string of 200 lbs
>tension, deflected by the bridge so that a net downbearing measurement of
>.018" (1 degree) is created, will produce a downbearing pressure of 3.6 lbs.
>(200 x .018).  More simple math.  Incidentially,  the bridge is pushing up at
>the string 3.6 lbs. at the same time the string is pushing down on the bridge,
>thus creating  a static equillibrium, like a depressed spring. An
>understanding of trigonometry is unnecessary, but can't hurt anyone.  
>
>I hope the above has been helpful.  Please contact Pianotek re: the missing
>instructions.  My apologies again.  Thanks for buying my gauge. Feel free to
>ask more questions.   
>
>
 Ron Nossaman