[CAUT] Backcheck replacement revisited (was: balancier/wippens report)

David Skolnik davidskolnik at optonline.net
Sun Dec 24 05:42:50 MST 2006


Israel -
As Mr. Burns would shisper, while rubbing his hands together, 
"Excellent"!! Your pictures  illustrate two critical points.
Notice how far below the top of the red Steinway check you have to go 
to find a relatively un-arced (vertical) surface as compared with the 
green Tokiwa. The more arc or horizontal the orientation of the 
surface, the more inclined the hammer is to impact and bounce off. 
The actual angle of the leather face, not the angle of the wire bend, 
is much farther off perpendicular in the Steinway than the 
Tokiwa.  Even if you make the correction in the Steinway angle (bring 
check more vertical), the distance between a perpendicular line drawn 
tangent to the surface of the most prominent part of the"bulge" of 
the Steinway check and a similar line representing the "active" catch 
surface is greater than the comparable two lines drawn on the 
Tokiwa.  The ramification of this is that, for like-shaped tails, the 
Steinway check would have to be farther back, to allow the tail to 
clear that bulge, than the Tokiwa. This would likely remain an issue 
even if the Steinway check were brought more 
vertical.  Geometrically, it's the difference between two convex arcs 
verses one arc and one flat surface, or in some designs, one convex 
and one, slightly concave arc.  The Steinway check would have to be 
higher and angle straightened to come close to the geometry of the 
Tokiwa.  That could present problems in the bass and tenor, with 
checks contacting hammer felt.

The wire dimensions would be useful.  The Steinway looks thicker, 
though that might be an illusion.  Still, the comparative wire 
characteristics would be interesting.  I wonder what, if any, 
functional difference there would be between these, which are 
installed at 90 degrees, then bent, verses the older style of angled 
installation.  For one thing, I think it alters the discussion about 
removing them or increasing the height.  I don't think you can 
effectively use hammer removing pliers directly under the heads with 
this type of wire configuration.  They would work in conjunction with 
a second gripping too, positioned at the wire bend.

Its easy to see why changing out these checks would solve your 
problem, without resorting to tail roughing or weakening springs.

Nice camera work.  Maybe we can talk to Sherry (of "We did something 
wrong" fame) , over there in Tuscaloosa to get you in to take some 
pictures while aWim's away skiing-not in Denver.

Too all - don't forget to keep those trees watered.


David Skolnik


At 01:46 AM 12/24/2006, you wrote:
>At 11:00 AM 12/23/2006, caut-request at ptg.org wrote:
>
>>Too bad you can't send some pictures.  While not conclusive, it 
>>would be interesting.
>>
>>Happy holidays
>>
>>David Skolnik
>
>Well, I got ambitious and took some pictures. Front view, side view, 
>and side view with the approximate angle when installed in the 
>piano. I hope they are useful. JPG files are attached. Steinway 
>current style - red felt, Tokiwa's old-style Steinway - green felt.
>
>Israel Stein
>
>
>
>
>

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