[pianotech] butt plate screws

[David Nereson]

On Fri, Feb 1, 2013 at 8:10 PM, Marshall Gisondi <pianotune05 at hotmail.com>wrote:

>  Hi Dave,
> Thank you for all of the info.  This piano is an old Lester upright, so
> tall you'd have to work on it standing up.
>

You have to work on almost all full uprights (52" or taller) standing up.


> The best way I can describe it is by what I'm feeling.  The reason I'm not
> sure if I access these screws from the back is due to the fact that when I
> put my finger on the brass rain at c88 where I can wedge my finger in from
> the side of the action bracket, I feel this screw that feels almost flush
> with the rail maybe a little recessed.
>

That's probably one of the screws that fastens the brass rail to the main
action rail.  No need to unscrew it.


> Now on the area where the hammer is not only loose but just literally
> sitting there non functioning, I feel this little metal thing protruding
> out almost feels like the threaded end of a screw, but I cannot feel a head
> on it.
>

That's probably the tab or tongue or prong -- I don't know the correct
term, if there is one.  There should be a hole in it.  If the butt plate
and butt plate screw are present, it will feel like there are TWO tabs or
tongues or prongs -- one of them rigid, or firm (the tab), and the other
loose and wiggly (the butt plate).  Since it sounds like you are feeling
only one protruding tab or prong, the butt plate and its screw must be
missing.  The butt plate often breaks in half at the screw hole and just
falls off.  In this case, the screw usually falls out of its hole in the
tab and is sitting on top of the action rail.


> This leads me to a couple of questions.  How do I know if the plate is
> missing?
>

There will be just the single tab protruding straight up from the brass
rail.  If the butt plate is there, it will feel like two tabs, about the
same size, one behind the other.


>   I hear and feel the center pin click when I put in place. So does that
> mean the plate is present?
>

Not necessarily.  It means the tab, at least, is present.  The groove for
the center pin is on the front of the tab.  If you place the center pin
against the very top of the tab and slowly slide the hammer butt downwards
(a quarter inch or less), you should feel the pin "click" into the
groove.   If the butt plate is present, it is in front of the tab (towards
the front of the action), and the screw holds it in place.  If the screw is
gone, then so is the plate, since there's nothing to hold the butt plate in
place.  The center pin is sandwiched, or clamped in place by the tab and
the butt plate.  Sometimes the butt plate rotates sideways, preventing you
from getting the butt into place.  It has to be rotated so it's parallel
with the tab, and slides up in between the "ears" of the hammer butt
(through which the center pin passes).


> do you remove the action in order to access this or do like some might do
> and just tilt it outward toward you in order to access the screw.
>

Either way, but if you just tilt it towards you, you need 3 hands, unless
there's something to keep the action from falling all the way forward.  If
you're inexperienced, I would take the action out and set it on the
keyblocks, using felt pads underneath, or if that doesn't work, on a nearby
table, or on the floor.
      Set the hammer butt aside for a moment (with center pin already in
it, of course), but have it within reach.  You have to put the new butt
plate into the butt plate inserter (holder) tool.  Hold the butt plate
against the tab, while you insert the screw from the back side of the brass
rail with a screw holder (screw grabber, screw starter tool, you know, with
the plunger and the 3 or 4 little grabber wires).  You may have to remove a
damper lever if the screw grabber is too fat to fit in between them.  If
you're up in the high treble with no dampers -- no problem.  Just get the
screw started.
     Some butt plates have two "legs" or "ears" that straddle a little nub
on the brass rail.  This helps keep it from rotating out of position.  Then
get the butt and (as in my previous paragraph), slide the center pin down
between the tab and the butt plate until it clicks into the groove.   Then
tighten the screw.  Sometimes in tightening the screw, the butt plate
rotates so that it rubs against the butt, causing the butt to be tight, or
sluggish.  You have to maybe loosen the screw and pry the butt plate over
with a tiny screwdriver or something, to get it centered again.


> Just in case anyone reading might wonder, I have had some exposure to this
> at the school. I just have trouble remembering which way the action was
> facing when we worked on this since it was already out of the piano.
>

If the work table is low enough, it doesn't matter much, although I think I
prefer working from the front of the action (dampers away from me).


> I mentinoed this because someone e-mailed Don at the school and asked if I
> was trained because of some trouble I was having with another repair, but I
> cannot recall which one it was.
>
> While I'm on this topic of remembering tasks, is this normal to neeed a
> refresher on tasks/repairs once in a whie?
>

Of course.  How many times do you have to re-pin the sostenuto tab of a
damper underlever?  I ran into this last week, and not having done it for
probably 10 years, it took me quite a while, since you have to hold the
tiny spring in place while trying to get the center pin thru the tab
bushing, the spring, and the underlever, all while holding the underlever
still and a center pin in the other hand, and you can't let that spring
loose or it will jump off to never-never land. . . . but I digress.


> I also have the Reblitz book.  I'm also curious as to how you guys know
> the part numbers off the top of you rhead like that amazing.  Oh just order
> screwdriver # .... amazing!  You guys are a great help.
>

Are you kidding?  I had to look them all up, to save you the trouble.

So to ease any confusion, this is definitly not a flange screw situation.
It is a hammer but plate arangement.

Good.  Glad that's straightened out.

I've never seen this on an old upright before.

Oh heck, LOTS of old uprights, especially players, had brass rails.

We had an old upright at the school with a weird hammer spring rail that
used cord loops or some sort of arrangement. I didn t work on this one, but
I recall it might have been from an old Bell brand piano.

Those are the Schwander- or Kimball-type butts I mentioned in the
previous response,
I believe.  Yamaha and Kawai and several other brands use them as well.  I
forgot to mention that in most modern pianos that have butt plates, you
loosen the screw only enough to be able to lift the butt off the flange.  The
butt plates stay with the butt as long as you don't take the screw all the
way out.  The flanges stay fastened to the main action rail.    With the
old uprights, you also loosen the screw only enough to be able to pull the
butt free, but the butt plates and their screws remain with the brass
rail(unless you remove the screw all the way, then the butt plate
falls off).

    A word of caution:  If you re-use old butt plates, tighten the screw
snug but don't over-tighten, or it may break in half like the old one did.
Use new butt plates if possible.  Sometimes they're too wide to fit in
between the "ears" of the butt and you have to file either the plate or one
of the ears thinner.   I go thru the action and just tighten all the
screws, quite snug.  Any that are split or on the verge of breaking
probably will break the rest of the way when I tighten.  That way,  I find
the weak ones and replace them.  If lots of them break left and right, then
it's expedient to replace them all.
     Also sometimes the new screws furnished with the new plates are too
long and the hammer will not return all the way to the hammer rail because
the butt hits the too-long screw before it has returned all the way.  It
hits the wood immediately behind where the butt felt is glued.  You can either
gouge out some wood, or easier, clip or file off at least 1/16" of the
screw.
     Another aggravating problem is that the tab sometimes breaks off at
the groove for the center pin.  This requires special repair parts, which
are still available, but don't work as well as they should.  If there are a
lot of broken tabs, it's easier to have that section of brass rail
replaced.

   I may have been wrong in my previous response.  It's usually the butt
plate that is threaded, not the tab.  That's why the screw can get lost
when the butt plate breaks, especially if the piano is tipped or moved up a
ramp, or if it falls off a truck.

    Brass rails can be a pain in the butt (pun intended), but their main
advantage is that the hammers usually stay spaced evenly and still aligned
to the strings over the decades whereas wood flanges can expand, contract,
warp, and shift left or right.


Well thanks everyone!! I sure appreciate you guys
Marshall

     You're welcome.  Mind your buts and butts.
--David Nereson, RPT




*Marshall Gisondi*
*MARSHALL'S PIANO SERVICE*
*215-510-9400*
*http://www.phillytuner.com *
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://www.moypiano.com/ptg/pianotech.php/attachments/20130201/10a9b56d/attachment.htm>