low drop screw symptom

[Bob Hull]

David, 

Your comments are appreciated.  Here's my answer to
your questions. 

--- David Love <davidlovepianos@comcast.net> wrote:
> What kind of piano is this?

It is a  5'6" Weber which was rebuilt by someone else
only 6 years ago but the pinblock was very poorly fit,
the wippens were not replaced and cheap parts were
poorly used. Now the wippens have failed (silk cord
type)so we decided to start over and hopefully do
things better.  
 
> If you have to lower the drop screw it may indicate
> that the bore
> distance on the hammers is too long.  Lowering the
> let-off button is
> usually accompanied by the lowering of the drop
> screw and vice versa.

Andre said something about capstans having to be
lowered and this is true, I am having to lower the
capstans on the samples to set the hammer blow dist.

> The shank relationship to the knuckle can be altered
> by changing the
> spread, shimming out the whippen flanges or the
> flange rail.  You will
> have to determine the appropriate spread by trial
> and error probably.  
> 
> The harder feel at let-off of the new wippen may be
> because the surface
> area of the top of the jack is greater on the new
> one than the old one.
> What condition are the knuckles in?  You may want to
> consider changing
> the knuckles if you are not changing the shanks.  

I am replacing the shanks but now I thinking about
trying a different shank with a bigger knuckle if I
can find the same dimension from the center pin.  I
hate not having the original parts to reference.

> I would measure and calculate just how much you need
> to lower the plate
> to get the bearing you want and on which side you
> have the problem.
> Also, measure the crown.  If you are lowering the
> plate onto a board
> which is already flat or worse...  Lowering the
> plate at the outside
> perimeter is not likely to change the hammer bore
> dimension.  Lowering
> the plate at the block might, it depends on how much
> you are lowering
> it.  Are you installing a new pinblock?

I have already put in a new pinblock.  The board was
repaired and coated with System 3 epoxy.
I lowered the plate as much as I dared, just enough to
get some downbearing but not push the board to hard
because of its age.  I did have to lower it also at
the block because the thread would contact the back of
the bridge before the front as it came from the
agraffe.     

> David Love
> davidlovepianos@comcast.net 
> 
> -----Original Message-----
> From: pianotech-bounces@ptg.org
> [mailto:pianotech-bounces@ptg.org] On
> Behalf Of Bob Hull
> Sent: Saturday, March 19, 2005 7:23 AM
> To: pianotech@ptg.org
> Subject: low drop screw symptom
> 
> Hello List, 
> 
> On a rebuild for a small but good quality grand I am
> replacing all of the action parts and having some
> doubts about the action configuration.   As I
> regulate samples the drop screw has to be lowered
> almost as far as it will go.  
> 
> Another relationship that appears to be off is the
> jack to hammershank relationship which is not
> perpendicular but rather it is more toward the B-
> side
> (Bob Hoff terminology).  How can I change this?
> 
> The new (Renner) wippen with the closest match to
> the
> old wippen is the one with the added heel.  The old
> jack tender/toe seemed to interface better with the
> tilted let off rail than the new wippen does.  The
> new
> one gives a harder feeling ledge before let off. 
> I don't like the way that feels.  
> 
> I  realize that more information may be necessary
> and
> I can supply it if asked.  One other thing I will
> add
> is that I had to lower the plate/string plane as
> much
> as I dared to get some downbearing.  I am adjusting
> the hammer bore because of this.  
> 
> So to restate my question:  What is indicated about
> an
> action geometry when drop screws must be lowered so
> far in order to attain suitable drop?  
> I would appreciate your comments.
> 
> Bob Hull
> 
> 
> 
> 
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