No Power Yamaha revisited (accurate bedding adjustment)

[Isaac OLEG]

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Re: No Power Yamaha revisited (accurate bedding adjustRon,

I find this procedure extremely useful to check the initial bedding and
particularly on less flexible frames.

Not all dial gauges can be inserted in all pianos, one may check the length
of the plunger (the
cheaper are the less tall) .

with the inverted position, very soon the lower extremity of the gauge is
touching the bottom, I have to use the tool with the keys pushed down, the
move when the bolt touch the frame is yet visible clearly, but one may be
careful not to push too strong on the key (and the frame)

The draw back is that once the piano is in the field(s), you check and move
the bolts so often that the initial bedding is less useful soon, I don't
carry a dial gauge with me for concert work.

And I like the idea of working with less tools (while if you see my tools
bag you may not believe that ;>)

How about this translation, was it checked for accuracy ?

Best Regards.

Isaac OLEG


Isaac OLEG

Entretien et reparation de pianos.

PianoTech
17 rue de Choisy
94400 VITRY sur SEINE
FRANCE
tel : 033 01 47 18 06 98
fax : 033 01 47 18 06 90
cell: 06 60 42 58 77

  -----Message d'origine-----
  De : pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org]De la
part de Ron Overs
  Envoye : samedi 24 mai 2003 04:43
  A : Pianotech
  Objet : Re: No Power Yamaha revisited (accurate bedding adjustment)


  At 12:26 PM +0200 23/5/03, Richard Brekne wrote:


    Yes... this is the proceedure I've been using for nigh on 20 years now.
Ever Since Laroy's first visit to Oslo. And as I have said, it generally has
worked well, but recently I have run into 3 instruments where this was not
enough. This proceedure left the keyframe bedded, with all glide bolts in
contact with the frame...


  (?)

     but there was lots of lost power, and lots of neighbor hammer bobbing
on hard blows,


  "Bobbing [adjacent] hammers" is a clear indication that not all glide
bolts were accurately adjusted.


  I remember back about 1990 when a Steinway tech visited Sydney for a three
day technical workshop. Two grands were to be regulated by a small group of
invited technicians.


  On the first day the usual paper shim under the bolts, lifting and tapping
procedure was demonstrated by the Steinway technician, to show the locals
just how it was done. I wasn't impressed since we had for some years been
using our own dial-indicator procedure (which is accurate and quick - a
while back the PTG published one of my documents detailing this procedure in
the Journal).


  On the second day of the seminar I bought in my dial indicator and wooden
mounting block, to demonstrate our procedure. Sure enough, the glide bolt
adjustment was 'all over the shop'. The visiting tech seemed unimpressed
with our alternative procedure. It never ceases to amaze me how many folks
stick with an inferior procedure just because its 'the way we've always done
it'.


  Anyhow, for those who may be interested in our procedure, I will take you
through the process.


  A dial indicator is mounted in a small wooden block with a single hole
sized to create a slight interference fit with the rear plunger cover of the
dial indicator (see diagram below).





  The mounted dial indicator is used to set exactly the adjustment of each
glide bolt, so that each just makes contact with the key bed. After the
precise contact position has been established, each bolt is re-adjusted down
a further small amount to ensure that the key frame doesn't lift the glide
bolts clear of the key bed during variable weather conditions.


  The procedure we use is as follows;


      * All glide bolts are adjusted up to clear the key bed while the touch
blocks are fitted to the piano and tightened. If an action has mid section
glide bolts (eg. Yamaha) you will need to remove a key over each one to
enable adjustment access with the action in the piano. These also are
initially adjusted to clear the key bed.


      * The dial indicator is positioned right next to each glide bolt in
turn, with the wooden block resting on top of the balance pins while the
dial indicator plunger is depressed by the underside of the pin block (and
showing a measurement which is mentally noted). The adjacent glide bolt is
adjusted down until the dial indicator moves just 1 thou' or 0.025 mm. This
procedure is repeated for all glide bolts until all are just contacting the
key bed.


      * Now repeat the adjustment procedure again, only this time adjust all
glide bolts down a further 5 thou' or 0.125 mm.


  That's it!


  The reason behind adjusting the glide bolts to a just-contacting setting,
before finally pre-loading the balance rail, is that the initial 1 thou' or
0.025 mm adjustment will not cause any positional change of the balance rail
which might interfere with the initial setting of the other glide bolts. The
end result is absolutely accurate and, provided that the front and rear
contact surfaces of the key frame to key bed are accurate, it will be quiet
and there will be no 'bobbing' hammers.


  Dial indicators are generally available at any good engineers supply. The
one illustrated above was lifted from the Cutting Tool Mall website at;


  http://www.cuttingtoolmall.com/catalog/standard.cfm?FamilyID=900100


  Cutting Tool Mall is in New York state, they sell on-line, and the prices
look OK. Furthermore, when used with a magnetic stand, the dial indicator
can be used between the plate and the bridge as the definitive tool for
adjusting the set bolts. We set-up our pianos with the set bolts just
contacting the plate in its resting position. There are many uses for a dial
indicator in piano work.


  On my return trip from the 2001 Reno convention I called on Richard
Davenport and toured his LA workshop. Richard had independently come up with
the same idea of using a dial indicator for setting the glide bolts. So all
roads do lead to Rome.


  Best,
  Ron O.


--
_______________________

  OVERS PIANOS - SYDNEY
  Grand Piano Manufacturers

  Web: http://overspianos.com.au
  mailto:info@overspianos.com.au
  _______________________

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