Bass hammer checking

[jolly roger]

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Hi Phil,
             Your problem is probably poor tail arc, and or check Rake,
(angle)   The radius of the tail needs to be 2 1/2" radius, and square with
the
hammer rail. Back check angle about 22 degrees back from vertical. And the
check height needs to have the centre line of the shank, at the top one third
line of the check at rest with the correct blow distance set.  1 7/8" approx.
Hope this helps.
Roger


At 06:45 PM 3/14/02 +0000, you wrote:
>Yesterday I worked on an older Baldwin with a Schwander action that
>had a characteristic that I've encountered on other grand pianos,
>some having it more than others.  The hammers check perfectly on the
>bench or when the action is pulled out in your lap, but won't check when
>the action is in the piano.  This behavior is usually only noticeable in the
>low end of the scale and becomes most pronounced at the bottom.  On some
>pianos it seems that you can't get the hammers at the bottom end to truly
>check no matter what you do; make the checking shallower, make it deeper,
>groove the tail, rough up the check leather, change the back check angle,
>reduce rep spring strength to almost nothing, etc.  When I say 'truly check'
>I mean behave as in the rest of the piano.  The hammer is held
>some distance below the string when the key is down and rises
>when the key is released.  Apparently some sort of 'checking'
>is going on because even on a hard blow the hammers don't bounce back to
>the strings.  But the tail isn't really being held by the backcheck when the
>key is down.  What's the reason for this?
>
>Phil F
>---
>Phillip Ford
>Piano Service & Restoration
>1777 Yosemite Ave - 215
>San Francisco, CA  94124
>
>
>
>2,000,000,000 Web Pages--you only need 1. Save time with My Lycos.
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> 

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