Leveling a plate? Del? Ron? Anybody?

[Bill Ballard]

At 12:02 PM -0500 4/1/99, John Hartman wrote:
>I may be able to help you with a technique to reestablish the correct
>heights of plate support dowels such as those found on Steinway and
>Mason and Hamlin grands. The method I learned from Angelo Andino,
>formerly with the belly department at Steinway, is fast and suitably
>accurate. It doesn't require any of those overly elaborate setups that
>were mentioned on this list earlier.
(Large Snip)
>
>Sincerely,
>John Hartman
>
>John Hartman Pianos
>Beacon New York
>Exclusively Grand Piano Re-building.
>>From Scratch Soundboards and Keyboards to the trade.

An even simpler method for removing spring from a plate. Of course large
amounts (>.250") require actual changes in the structure.

Get your 12" Starrett machinist rule with the 16R (aircraft) readings and
measure the vertical distance from the top of the rim to a spot just
adjacent to the plate lag below: first with the pinblock screws and all rim
bolts tight on (but nose bolts down & out of the way), then second, with
the block screws tight and the rim bolts out. #1 - #2 = the distance each
plate shoe(?) has lifted up off its dowels. Moderate amounts of spring can
be removed by filing down the dowel pairs having a greater than zero
reading, an amount equal to their measured spring, adjusted by the ratio of
its ditsance straight back to the plate pinblock flange compared to that
distance of the nearest "zero-spring".

In the hand filing, I measure with a pair of drill bits from the numbered
set floating around on either side of the dowels. I start off with
woodcarving rifflers and finish with a metal file.

I just finished this process on the S&S B which I mentioned last June here,
concerning treble sustain and how nose bolts could induce a plate stiffness
which might benefit the sustain. The board before teardown (1941 factory
restring with belly) showed no bearing or at least negative front bearing
for the bottom 2/3 of the long bridge and the top 1/2 of the bass bridge.
Looking at the bearing after removing the strings, with a thin soft steel
wire showed negative bearing. There was a crown. Using the above method for
trimming plate dowels, I combined the amount that each plate screw would
need to drop to provide positive bearing from the string directly in line
with it, with the amount that I didn't have to carve because a plate shoe
was already above its dowels. I got my bearing. In the last bolt-down of
the plate, I measured plate spring. The extreme was .06" and the average
was around .02" (just a shade over 1/64"). Respectable considering the
dowels behind the bass bridge had to drop by .06".

The piano now restrung (with the 1941 factory block) has far more depth and
sustain and most appreciably in the 5th and 6th octaves. It's definitely
not rocket science, but then you don't have to work for the government for
a few years to be able to afford the equipment.

Bill Ballard, RPT
New Hampshire Chapter, PTG

"When you do, you will"
        Albert to his charge, Chris, in "What Dreams May Come"