Lowell Component Downbearing Gauge

[John Delacour]

At 9:28 am -0500 14/5/07, David Skolnik wrote:

>...Dale's gauge seems to have a comparable vulnerability in its 
>'blindness' to the bridge surface and the anomalies that can be 
>introduced.  For example...a bridge surface which angles upward 
>(creating "negative front bearing"), then has the string return to a 
>point exactly on a line with the extended straight line of the 
>sounding length of the string, would show no bearing, yet it would 
>be present, albeit in a distorted form.

Hello David,

Do you mean something like this, where the pin is held in contact 
with the bridge only by the downdraft from the angled front pin?  If 
so, then without the pin there would be no angle and thus no 
downbearing.  As it is, the forces are acting to pull up the front of 
the bridge and push down the back, which results in a moment about 
the centre of the bridge top and no net downbearing. Surely this is 
not a well piano.



>   The Lowell would show that information, however, without the 
>additional information from an Erwin-style tool, it would be 
>difficult to determine the net-effect.
>
>Would you be satisfies with Lowell gauge with a better vial, wider 
>distance range, with magnetic feet? What would it's shortcomings be 
>at that point? besides price?

I can only judge the Lowell tool from reading the patent and looking 
at the accompanying drawings, since I haven't seen one or even a 
photo of one.  To me it looks and sounds far too complicated and 
fiddly and thus, since it is not built as a precision instrument with 
a price to match, prone to error.  A far simpler and more robust tool 
can, I am sure, do a better job and return more precise results more 
quickly.  I can't really work out the point of the bubble vial at 
all, since all the measurements are relative if we are considering 
only downbearing.

All that is needed in principle is a rigid bar or tube with two legs 
slidable on it and one non-sliding leg at one end whose height can be 
adjusted by means of a screw fixed to a dial.  Supposing the screw to 
have a pitch of 1 mm. and the dial to be 32 mm. in diameter with 100 
marks spaced at 1mm round the perimeter, then each millimetre on the 
dial will indicate 1/100 mm., or even more accuracy could be got with 
a finer thread.  The measurements can then easily be used to 
calculate the angle and the downbearing.  Such a tool can be made 
extremely light, strong and durable and the only calibration it 
requires is to zero the dial when all three points are touching a 
perfectly flat surface.

I have no interest in depreciating the Lowell tool and I might change 
my mind if I actually had one to play with and get the feel of, but 
in all design I like the utmost simplicity combined with great ease 
of use and excellent function.

JD




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