Korean Dip

[Dean May]

>>and let's take the simplest case of removing a punching at the front rail
- the repetition travels farther, pushing the hammer into the string after
letoff. To correct it, we lower the drop screw. However, that means it's on
the drop screw longer before letoff occurs, it compresses the spring more,
and tends to have more resistance and a spongier feel.

 

 

This is becoming increasingly frustrating to me as my regulating skills
continue to develop. I never used to notice it but now I do and it bugs me.
So, how does one reduce the time on the drop screw? Reduce blow distance?
Reduce action spread? Move knuckle? 

 

Usually there are two scenarios we are talking about: one is just doing a
regulation, the other is when extensive action work is involved (changing
parts). If the latter one would certainly have opportunity to make
additional changes, such as varying the bore distance on the hammer. So I
guess I am looking for two answers, one for each situation. 

Dean

Dean May             cell 812.239.3359 

PianoRebuilders.com   812.235.5272 

Terre Haute IN  47802

 

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From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of BobDavis88 at aol.com
Sent: Wednesday, January 30, 2008 7:42 PM
To: pianotech at ptg.org
Subject: Re: Korean Dip

 

In a message dated 1/30/2008 3:41:06 PM Pacific Standard Time,
paulrevenkojones at aol.com writes:

Aftertouch, as a component and resultant of regulation, becomes so apparent!

I've always thought that the various effects of aftertouch were underrated.
When I was first learning, it was presented as a "safety factor" in case of
compaction of the knuckles, etc., so the action would still have escapement.
However, other things happen. For instance, if we increase the aftertouch -
and let's take the simplest case of removing a punching at the front rail -
the repetition travels farther, pushing the hammer into the string after
letoff. To correct it, we lower the drop screw. However, that means it's on
the drop screw longer before letoff occurs, it compresses the spring more,
and tends to have more resistance and a spongier feel. Conversely,
shortening aftertouch makes the contact with the drop screw later in the
sequence, and speeds up the repetition.

 

I also haven't seen mention of its effect on checking. If the checking is as
high as possible without the hammer tail dragging on the check on the way
up, then we allow the key to go down farther, the backcheck moves farther,
catching the hammer higher, which is also good for repetition. As everything
in the piano, a tradeoff.

 

I don't have a fixed distance for aftertouch - it's dependent upon how the
action feels. Over the last two days, I have regulated a new Kawai RX-3 and
a new Mason & Hamlin A. For a variety of reasons, the Kawai would accept
more aftertouch than the M&H without balking, although it wasn't necessary.
The jack drag in the M&H was great enough that the minimum seemed the only
choice.

 

On a performance instrument, I usually start without very much aftertouch,
maybe .025-.030. Some pianists feel insecure without the resistance at the
bottom, and for them, it's usually enough to put the hammer line up 2-3 mm
and run the drop back up, which doesn't take long, and they don't usually
notice the loss of power. There's usually not time in a concert situation to
change the dip.

 

Anyway, there's more going on than "safety factor."

 

Bob D





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