[CAUT] Gram Tension Guages

[Don]

Hi David,

Think of the difference between "rolling" friction and "sliding" friction.
The correct friction may only be measured when the flange is actually
rotating.


At 08:31 PM 5/18/2006 -0700, you wrote:
>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
>
>
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Regards,
Don Rose, B.Mus., A.M.U.S., A.MUS., R.P.T.
Non calor sed umor est qui nobis incommodat

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