[CAUT] Gram Tension Guages

[David Ilvedson]

Don,

Explain "gram measurement should be of the flange while it is rotating"...?

David Ilvedson, RPT
Pacifica, California



----- Original message ----------------------------------------
From: "Don Mannino" <DMannino at kawaius.com>
To: "College and University Technicians" <caut at ptg.org>
Received: 5/18/2006 4:33:12 PM
Subject: [CAUT]  Gram Tension Guages


>List,

>I prefer to use gram gauge specifications.

>I agree with Rick Baldassin, that using swings results in added friction
>in the bass.  This affects the touch, which can affect the weigh off and
>inertia (depending on how you do your weigh off). This tapering of the
>friction is not recommended by any piano makers that I know of.  The
>weight of the heavier bass hammers already assures greater friction
>(from the knuckles) in the bass, and this added friction works perfectly
>to maintain control of the heavier hammers.

>One can also try to taper the swings, but as Jim pointed out, this is
>rather inexact, resulting in uneven friction.

>When repinning an action, I get my friction spec by doing a few test
>flanges in the mid treble, where the tone of the piano reveals problems
>most quickly.  If the bushing cloth quality is sufficient to allow 2
>grams friction on the hammer flanges in this part of the scale with good
>solid tone, then this will be enough for the rest of the piano.  If the
>cloth is spongy, then a tighter fit will usually sound better.

>It is also good to adjust the fit according to the weather.  Pin tighter
>by a couple of grams when it is humid.

>The gram measurement should be of the flange while it is rotating, not
>the starting friction.  When pinning to a published gram specification
>you should measure at the screw hole, but for consistency it is simpler
>to just measure at the end of the flange.   This takes a little
>practice, but is not too hard.

>Don Mannino RPT