jack not returning on high treble

[Michelle Smith]

Hi David and all who have made suggestions.  Yes, I flicked those jacks to
make sure the spring was still strong enough.  To be very specific, here are
the tests I did and they come from the PTG Technical Source Book.  Fern
Henry's article, Diagnosing Repetition Problems in Vertical Pianos. 

 

1.	I checked for slow hammer return by moving the hammer rest rail
forward and back.  (No slow hammers.)
2.	I checked for lost motion by pulling on the hammer rest rail.
(There was some lost motion.)
3.	I checked the wippen centers by holding the keys down at the back
and lifting each wippen with the other hand.  (Every wippen was fine.)
4.	I checked each jack by depressing the soft pedal and tripping each
jack.  (They were happily snappy.)
5.	I checked the keys by raising the wippens below the key bed
(remember it's a drop action) and tapping the rear of each key.  (Key travel
was fine.  No friction at balance rail or front rail.  They were actually
very loose.)

 

The reason this is throwing me for a big loop is because the action parts
"seem to be fine" and the keys "seem to be fine".  Something isn't right.
To add to the weirdness, it is only the notes without dampers!

 

In this same thread Paul suggested the following:

 

"Try reducing the hammer blow by shimming the hammer rail with punchings and
see what happens. If it has any effect, then make it a permanent repair on
the hammer rail, and accept the blow distance as the necessary compromise
for the time being."

 

I tried that and the jack still tripped out and wouldn't return. 

 

The only way I could get the notes to repeat was to adjust the let off so
that the note was practically blocking against the string.  By doing this,
the jack wasn't actually coming out from under the hammer butt and the
feeling when playing the notes was totally wrong.  So adjusted them back to
their original non-functioning position, and called it a day!  =) 

 

The more I'm typing, the more I think it has to be the key dip problem.  I
think I better go sleep on this one.  

 

Keep those suggestions coming!

 

Michelle Smith

 

 

 

 

  _____  

From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of David Ilvedson
Sent: Tuesday, January 23, 2007 11:15 PM
To: pianotech at ptg.org
Subject: RE: jack not returning on high treble

 

 The dampers help return action parts to rest...not their design
necessarily...you will need to get the dip the same and probably need a
slight bit of lost motion...adjust and cycle action slowly to see that jack
returns.   Of course you have flicked jacks to make sure the jack spring is
strong enough or jack center isn't tight

David Ilvedson, RPT
Pacifica, CA 94044

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