slow returning hammers

[Tom Driscoll]

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-----Original Message-----
From: pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org] On
Behalf Of Elwood Doss, Jr.
Sent: Sunday, December 21, 2003 12:12 AM
To: Pianotech
Subject: Re: slow returning hammers

 

How about a mixture of wood alcohol and water to cause the bushing to
swell, thereby loosening the pin?  Might work.

 

Once the action is dried out, what's to prevent the moisture coming back
and the action centers becoming sluggish again?

 

Joy!

Elwood

 

Elwood Doss, Jr.

            

            Elwood,

            This is a well established technique. The pin is not
affected. The bushing cloth made of wool changes dimensionally after the
water saturates the fibers and dries. Years ago I read a journal article
describing exactly what happens to the cloth during this process .I
could dig the article up to refresh my memory, but suffice it to say
that a tight center will usually become free after treatment. Many
Baldwin Acrosonics from the 60's have tight centers that respond to the
Alcohol. - Water treatment. 

            As to the second part of your query: Yes. The action will
continue to be affected by humidity, but even without climate control, a
piano action should remain playable even in high humidity environments.
In my experience the problem generally will not return especially with a
protect application (if necessary) after every thing dries out. 

            Its important to check that the centers don't become too
loose so don't lubricate if not required. Gram resistance can be
measured or use a swing test of the part (I look for around seven swings
of the hammer) 

            The archives are loaded with different formulae, but I've
had success with very cheap vodka- 

            Only be careful---I once left the bottle on the bench when a
client came into the shop. OOOPS!

            Tom Driscoll RPT

            

 


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