[pianotech] Jack and Damper Spring Tension Targets

[Gregor _]

The damper spring tension should decrease from bass to treble. Sometimes I see in old pianos a pencil line on the damper levers which goes diagonal over all the levers of one area (bass, tenor, treble). I was told that this line was used to measure the spring tension, but I was not told how exactly that procedure works. Does anybody know?

Gregor

------------------------------------------
piano technician - tuner - dealer
Münster, Germany
www.weldert.de




> From: fg at floydgadd.com
> To: pianotech at ptg.org
> Date: Wed, 29 Jul 2009 06:03:25 -0500
> Subject: Re: [pianotech] Jack and Damper Spring Tension Targets
> 
> Hi Gregor,
> 
> Ted's CAUT post of Oct 15/07 is quoted below.  He was responding to a post
> from David Ilvedson, as noted.
> 
> What I'm exploring here is new ground for me, and I'm trying to establish
> points of reference.
> 
> Thanks for your interest!
> 
> Floyd Gadd
> 
> 
> Gregor wrote:
> 
> That´s what I was wondering about, too. And how do you do it? Do you
> dismount the whippen including the jack for measuring?
> 
> Concerning the damper spring: 40 grams on which damper? Bass or treble?
> 
> Gregor
> 
> 
> 
> [CAUT] Upright geometry problem (Nordiska)
> Ted Sambell edward.sambell at sympatico.ca
> Mon Oct 15 13:25:30 MDT 2007
> 
> 
> Several years ago I attended the Europiano convention in Germany, at which
> engineers from Schimmel dealt with this question. For the jacks, simply use
> a force gauge, placing the feeler on the jack heel and moving the jack
> forward  with it. The recommended reading is 30 grams, not more. To check
> the damper springs, mount the action on the bench horizontally with the
> dampers uppermost and use the force gauge on the damper felt to press
> downwards about the distance of the damper lift. The optimum reading is 40
> grams. The engineers said that increasing the spring strength above this
> does not improve damping efficiency. In my experience I have found that
> excessive spring strength also causes hammer bobbling.
> 
> Ted Sambell
> 
> >I know how to reduce or increase the tension it is getting it even that I'm
> >wondering about...some sort of gram gauge pulling on the damper?   Maybe it
> >is simply trying to pull the spring towards you the same amount for each
> >damper?
> >
> > David Ilvedson, RPT
> 

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