Component Downbearing Gauge Measurements

[Ron Nossaman]

>
>The instructions state "  Multiply the number of divisions the bubble
>crossed by three, and one has the net bearing, in thousandths."  For
>example, I took this to mean that if the bubble moved 3 division marks from
>the point where it was calibrated, that would mean .009" of downbearing (3
>division marks, x .003" each = .009").
> 

Yep, right gauge, but I didn't get any such instructions with it (at least,
I don't remember reading that). 



>The instructions don't say that the tool is calibrated in 3/16 degree
>increments.
> 

Mine didn't either, I took a combination square with the protractor head and
figured it out. I thought it was pretty sad that a useful tool like this
didn't come with any basic information as to it's calibration. The problem
is that, whereas angular measurements in degrees mean the same to everyone,
thousanths are meaningless unless you know how the mearurement was taken.
Since the gauge is used to measure angles, why wouldn't they tell you what
the reading means in degrees? 




>One last question... I know that downbearing measurements can be calculated
>to indicate how many pounds of downbearing exist in a certain string.
>Downbearing can be expressed as the amount of force that the string is
>pushing down on the bridge (for example - 1.9 lbs).
>
>But is it possible to express downbearing in thousandths of an inch like I
>did?
>
>I just got this tool last night, and I stayed up late reading Nick
>Gravagne's articles in the JOURNAL from 1989 and 1992.  I guess I just got
>carried away!  The April 1989 JOURNAL has Nick Gravagne's article on
>Lowering the Plate: Part 1.  It had some calculations on Page 31 about how
>to figure the bearing angle using trigonometry [which my wife explained to
>me :-) ] and I was hoping to figure out how to change the readings in
>thousandths of an inch to readings showing degrees of Bearing Angle.
>
>Thanks,
>David
>
>David A. Vanderhoofven, RPT
>#pianotech page:  
>http://www.clandjop.com/~dkvander/ircpiano.html
>
>New web page for the Joplin Community Concert Association
>http://www.concerts.joplin.com
>

I'll send you a chart, privately so the rest of the list won't have to look
at it again, that should answer most of the questions.


 Ron Nossaman