[pianotech] problem in mating hammers to strings

[tnrwim at aol.com]

David

When you say you level the strings, do you use Joe's level, or do you just feel that all the strings are in the same plane?

It really doesn't matter if the strings are perfectly level, as long as the hammer hits all three strings at the same time. That's what you've got to go for, even if the hammer looks uneven. 

Correctly spaced hammers next to each other can travel at an angle, and not touch each other. The best way to check this is to bring the hammer up with a hook, or and see if it comes up straight or at an angle. 

Wim







-----Original Message-----
From: David Nereson <da88ve at gmail.com>
To: pianotech <pianotech at ptg.org>
Sent: Tue, Mar 1, 2011 4:40 pm
Subject: [pianotech] problem in mating hammers to strings


I've encountered this several times now with grand pianos.  I 
evel strings.  Then for each unison I hold the hammer up 
gainst the strings by pressing upward on the jack tender, and 
luck the strings.  The ones that ring aren't being damped by 
he hammer.  The ones that don't ring are being damped, 
ndicating (supposedly) that the hammer is "high" under that 
tring.  Trouble is, I get the indication that all the hammers 
n the low tenor are high on the right.  Yet when tipping the 
ront of the action up and viewing the strike points (which 
ppear just above the flange screws from this vantage point), 
hey appear straight across.
 _ _ _ _ _ _ _ _ _ _ )
   If I then file the right side of each hammer so that all 3 
trings of each unison are damped equally when holding the 
ammers against them, then look at them again from the front, 
hey appear like the teeth of a giant rip saw  (|\  |\  |\  |\ 
\  |\  |\  |\ , but imagine the line slanting to the right --  
he strike point-- slants only about a third as much as the 
ackslash.)  But when I leveled strings, nothing told me that 
he right string of each unison was low, especially not that far 
ow.
   This problem doesn't occur in the section with 
on-angle-bored  hammers nor in the capo sections.  So I'm 
ondering if, because of the angled hammers (not in line with 
he shank), the shank flexes when pressing up on the jack, 
ausing the hammer to lean to the left, and giving me a false 
ndication of how the top of the hammer is shaped.
   I've also had situations when, after spacing hammers, some 
f them still get thrown aside slightly on a hard blow, so that 
ne unison string doesn't sound as loudly as the others.  In 
ther words, the angle bore or something else is causing the 
ammer to travel or lean on a hard blow.
   --David Nereson, RPT 


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