No Power Yamaha revisited (accurate bedding adjustment)

[Isaac OLEG]

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Re: No Power Yamaha revisited (accurate bedding adjustNice tool, and trick !
making a hole and inserting a match in the card, you can even see better  I
guess.

Best



Isaac OLEG

Entretien et réparation 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 Kevin E. Ramsey
  Envoyé : samedi 24 mai 2003 04:57
  À : Pianotech
  Objet : Re: No Power Yamaha revisited (accurate bedding adjustment)


  I wrote of this before, what do you think of my method, Ron. I mean, who
needs a dial indicator when you have a business card?

  "David, and all, your method is quite a bit like mine. Rather than buy a
Jaras tool, you can do the same thing without it.
      What you're looking for is the fact that when the balance rail
contacts the keybed the keys will begin to raise. I take a business card and
cut it so that it's just a little taller than the keybed-keytop distance.
When you put it under the keytops, it will form a slight curve. Then, I put
the balance rail bedding tool on the glide and, as you describe, push down
on it. If it's not bedded you can see the card flex quite dramatically. Then
you can turn the glide bolt in, and as soon as the glide bolt contacts, the
card will start to straighten out. Work from the center out, when you're
done, you can do the "lift and tap" final check.
      This get's you real close, real fast.

      Hey, a card's a lot cheaper than any other tool I know.
  Kevin."




    "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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