K52 Damper Felts on an 1883 Model F

[Bill Ballard]

List,

Has anyone else tried to put Steinway K52 damper felts on one of 
their 19th century verticals? (I've restrung the piano, and it's also 
getting new double flanges and Tokiwa damper levers.

There are significant differences between the origial Model F felts 
and the K52 felts, but it's not until I get into the bass section 
that I have to make a significant departure from the new felts to get 
things to work Each of the K52 felts has a felt pad at the top of the 
front side (the string & damping side being the back side), and this 
pad is glued on top of the layer of thin felt covering the veneer 
strip which is the foundation of each damper felt. I can't get to a 
K52 to see the factory's installation, but I'm assuming that the red 
pad sits on the top of the wooden damper block and serves to center 
the length of the damper felt on he block (In the treble, these pads 
are 7/16" long. At #73, the top treble, the centering is 50-50% and 
at the other end of the flats, #38, it's 33-66% above-below. In the 
treble trichord, and the bass, it's 50-50%.)

The bass gets bent out of shape, because of the difference between old and new:

	O'all L	Pad L	Angle
Old	1-5/8"	1/2"	35º
K52	2-3/4"	1-1/4"	75º

"O'all L" is the overall length of the damper. "Pad L" is actually 
how far below the top corner of the felt the top corner of the block 
gets glued, which with the K52 would equal the pad length. (In the 
original, there is no pad.) The "Angle" is how far off vertical the 
damper wire gets bent to properly locate the block over the string.

75º? Yep, that's 15º up from horizontal. All because of the K52's 
extra 1-1/8" length and the gluing spot as dictated by the pads, both 
of which drive the location of the block downwards.

While the immediate objection to that 15º inclination is that the 
dampers block don't clear the hammer spring rail (- I need 3/16" up @ 
#1 and 5/16" @ #26), the other problem with these damper block 
location is the efficiency of the dampers. Being just 15º off of 
level, their lift off the bass strings has been decreased by an 
amount which I can't gage at this point of the action reassembly, but 
which I don't care to gamble on.

Anybody out there made it of this kind of situation alive? My main 
problem is the selection of K52 for a set of ready-made tall upright 
damper felts. This stuff is no longer available from Yamaha (without 
a SN).

My choices are shorten the O'all L, raise the block-damper back glue 
spot (and upset the centering) or both. The low bass dampers from a 
Yamaha U3 set (one of the last I snagged from Schaff last Fall) is 
2-1/2" long, with the centering 25-75% above-below. And the gluing 
area of the original Steinway F blocks is probably 80% greater than 
Yamaha's dowel block.

I can easily get the clearance I need for the spring rail by 
shortening the pads (or even easier, chopping of 1/2" in length from 
the top/pad end of the damper). If Yamaha dares to center the felts 
25-75%, I suppose I can. But until I significantly shorten the damper 
length, I'm stuck with a damper wire bend in the bass which looks 
like it belongs on a 42" console piano, not this proud 54" vertical.

Anybody been there and doo-dooed that, already? Anybody have any 
rules of thumb for overall damper length or centering of the felt 
over the block in the bass section of a tall upright?

Muchos Thaquos in abencia,

Bill Ballard RPT
NH Chapter, P.T.G.

"May you work on interesting pianos."
     ...........Ancient Chinese Proverb
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