bobbling hammers, again

[Richard Brekne]

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.


Bass notes ?? lowest area ?? or where ? 

One thing I find often helps is firm hammer shank centers and making
sure the hammer is square to the strings. Check also that the shank is
not too flexible... rubber shank syndrom... can cause the hammer to
wobble so severely both up to and from impact that it never has a chance
to seat in the check. 

This is never a whippen problem, and an adjustment of the rep lever
spring is never the answer to a checking problem. That is to say... as
long as the rep spring is within normal parameters to begin with.

Cheers
RicB

> 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

-- 
Richard Brekne
RPT, N.P.T.F.
UiB, Bergen, Norway
mailto:rbrekne@broadpark.no
http://home.broadpark.no/~rbrekne/ricmain.html
http://www.hf.uib.no/grieg/personer/cv_RB.html