Jack pinning...do they bend?

[Dave Davis]

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Hi Dean,
I have run into the problem you mention on Young Chang and Samicks from the late 80's and into the 90's, and am aware of plating problems, felt that was not pre-shrunk properly, graphite in the felt, and scratches on the pins from tight pinning, but this jack pinning problem seems different.  I will check with YC on Monday. 
 
So I'm getting the impression that jack center pins can not be bent even from heavy abusive playing?
 
Dave Davis

Dean May <deanmay@pianorebuilders.com> wrote:


Bergman is a Young Chang product and you will frequently encounter this problem of hammer centers tightening on YC products. It is residue from the felt. Ream and repin the ones that are bad. Protek all the rest. 

 

To see which ones are bad, lift all the hammers up to vertical. Then start lowering them to the rest rail, watching to see when gravity will overcome the friction. You’ll be able to see which ones are really bad, as they will go down to quite an angle before gravity will get them. When friction is about right, hammers should fall when they come off center, about 75 degrees.

 

Dean

 

Dean May             cell 812.239.3359

PianoRebuilders.com   812.235.5272

Terre Haute IN  47802

 

-----Original Message-----
From: pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org]On Behalf Of Dave Davis
Sent: Saturday, July 03, 2004 5:16 PM
To: pianotech@ptg.org
Subject: Jack pinning...do they bend?

 

Hi All,

 

Is it possible for jack center pins to be bent on a hard blow? I service a Bergman TG150 (5'0") that is played very hard, and some of the jack pinning is getting tighter. At first I thought it might be tight bushings or an adult beverage spilled inside (bar scene), but I'm thinking the pins may be bending. The piano is 7 months old. I don't think the problem is a pin plating problem or graphite in the bushing felt.

 

Dave Davis


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