pianotech-digest V1997 #1919 (long)

[Roger Jolly]

Hi Richard,
                 On the subject of  V vs U  with regards to termination
bars. Having watched plates being dressed in several piano factories, the
quick way of shaping these bars is with a file or small grinder hence the V
shape.
 All too frequently the terminations closest to the plate webs are poorly
shaped, and is clearly in evidence by the amount of V bar noise we fine in
this area.

In theory two perfect circles touching will give an infinite contact point,
( just imagine they don't touch, grin.)

I have asked two major manufacturers why they don't shoe shine the pressure
bars with emery paper to obtain a clean radius, the answer in both cases
was that it is not necessary. I'll take this to mean that the extra 1/2hr
of work cost money. In one plant the concert grands had the pressure points
polished to a nice round radius, hence contradiction their previous
statements.
The other plant, the concert grands had case hardened termination pieces
with perfectly formed radii.
When ever I restring, I'm always careful to get as clean a polished U shape
as possible, and tend to believe that there is less friction, and cleaner
and more consistent termination.

V is time saving, U cost money IMHO.

Harold Conklin's case hardened steel termination pieces, have about 10 to12
times radius vs 6 or 7 this I belive was done to control the amount of
power in the forward duplex, and the difference in sound absorption with
steel vs cast. 

More mud to cloud the waters.

Roger 

Roger Jolly
Baldwin Yamaha Piano Centre
Saskatoon and Regina
Saskatchewan, Canada.
306-665-0213
Fax 652-0505