bobbling hammers, again

[Tim Coates]

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Wim,

I've been finding lately a problem with the height of the backcheck on 
SS.  They have been too low.  It causes the problem you describe.  

Divide the backcheck into thirds.  At rest the centerline of the shank 
should line up with the line between the middle and upper third of the 
backcheck.  Use a "snap ring" pliers (automotive store) to raise the 
backcheck.  

I checked everything that has been suggested to you and still had the 
problem.  A friend suggested this.  Sure enough it worked perfectly.   I 
was astonished how far off the backchecks were and how well the action 
worked once this was corrected.

Tim Coates
University of South Dakota
University of Sioux Falls    

Wimblees@aol.com wrote:

> Several months I asked about bobbling hammers in a grand. I discovered 
> that the shank lenght was too long.
>
> I now have a similar problem with a D. But this time, I've rebuilt the 
> action with new Steinway parts, (new h,s,f and wipps). There are three 
> notes that are driving me nuts. Unless I really smack the note, the 
> hammer doesn't want to check. They boble so bad that they hit the 
> string on the rebound.
>
> The regulation is just like the other notes, (dip, l.o.,drop, etc.). 
> Not only is key dip just like its neighbors, but when I increased key 
> dip, it didn't solve the problem. There is enough damper lever 
> clearance. I've adjusted the back checks to where the hammer checks 
> almost back down on the cushion. When I try to make it check earlier, 
> it catches. I've bent the checks so that the rake is enough to clear 
> the hammer on the way up, but still catches it on the way down. I've 
> reduced spring tension to the point of almost no rise, and I've sanded 
> the backs of the tails. I even changed wippens on one key, but the 
> problem is still there.
>
> What are some other things I should look at?
>
> Wim 



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