[pianotech] problem in mating hammers to strings

[Dave Swartz]

A couple of tricks I've discovered (just in case I may have missed something
in previous posts) is on the bench, use the "leading" edge of your let off
bar (I use a Jaras jig) and ascertain the perfect "level/square" of the
hammer to the bar.  In other words, slide the let off bar backwards to where
just the edge is at the strike point and allows you to see exactly if the
hammers are mis-shaped or correct.  In the piano, pluck the strings when
lifting the hammers as Wim mentioned to achieve the same tone/decay.  If one
rings longer then an adjustment is necessary.  If the hammer is flush and
correct to the strings, then check the level as I've found even using a
leveling device such as the Mother Goose level still requires individual
'tweaking".  Make certain you "play" in those hammers after reshaping that
the felt is indeed ready for final tonal adjustment.

Just my 2 cents...don't spend it all in one place...LOL

Dave Swartz, RPT
Cory Products
www.corycare.com



On Tue, Mar 1, 2011 at 9:33 PM, Paul McCloud <pmc033 at earthlink.net> wrote:

>  Hi, David:
>     I came across the same thing, but mostly in the bass.  It perplexed me
> until someone on this list explained it.  I think it was Frank Emerson.  The
> geometry of hammers bored at an angle is very complex, and surprising things
> happen.  The striking surface of an angled hammer doesn't stay level as it
> swings.  Straight bored hammers will always stay level.
>     To illustrate, take a small jar in your hand and keep the axis
> perpendicular to your arm and level to the floor.  If you lift your arm,
> you'll see that the jar axis will always stay level.  Now angle the jar, and
> raise your arm.  One end of the jar will be higher than the other as the
> axis begins to tilt.
>     This may help envisioning why you're having trouble this way.
>      Angled hammers must be hung so they are perpendicular to the strings
> as they contact, not as they rest on the rail.   Perhaps your hammers aren't
> hung properly..
>     I hope this makes some sense.
>     Paul McCloud
>     San Diego
>
>
>
> ----- Original Message -----
> *From:* <tnrwim at aol.com>
> *To: *pianotech at ptg.org
> *Sent:* 03/01/2011 6:54:13 PM
> *Subject:* Re: [pianotech] problem in mating hammers to strings
>
> 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
> level strings.  Then for each unison I hold the hammer up
> against the strings by pressing upward on the jack tender, and
> pluck the strings.  The ones that ring aren't being damped by
> the hammer.  The ones that don't ring are being damped,
> indicating (supposedly) that the hammer is "high" under that
> string.  Trouble is, I get the indication that all the hammers
> in the low tenor are high on the right.  Yet when tipping the
> front of the action up and viewing the strike points (which
> appear just above the flange screws from this vantage point),
> they appear straight across.
> ( _ _ _ _ _ _ _ _ _ _ )
>     If I then file the right side of each hammer so that all 3
> strings of each unison are damped equally when holding the
> hammers against them, then look at them again from the front,
> they appear like the teeth of a giant rip saw  (|\  |\  |\  |\
> |\  |\  |\  |\ , but imagine the line slanting to the right --
> the strike point-- slants only about a third as much as the
> backslash.)  But when I leveled strings, nothing told me that
> the right string of each unison was low, especially not that far
> low.
>     This problem doesn't occur in the section with
> non-angle-bored  hammers nor in the capo sections.  So I'm
> wondering if, because of the angled hammers (not in line with
> the shank), the shank flexes when pressing up on the jack,
> causing the hammer to lean to the left, and giving me a false
> indication of how the top of the hammer is shaped.
>     I've also had situations when, after spacing hammers, some
> of them still get thrown aside slightly on a hard blow, so that
> one unison string doesn't sound as loudly as the others.  In
> other words, the angle bore or something else is causing the
> hammer to travel or lean on a hard blow.
>     --David Nereson, RPT
>
>
>
>
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