No Glide Bolts

[Isaac OLEG]

Hello,

Some grands that have key frames without bolts, have nowadays a system
on the blocks to push the keyframe firmly in contact with the keybed
(Seiler, for instance).

Yes the key frames are supposed to be very stable when mounted without
glide bolts, but they warp all more or less at a moment or another
(Bosendorfer, Bechstein, etc).
The bedding  I try to do from the front rail, but if a really too
large gap under the balance, glue some veneer and sand till firm.
Tricky and long in any case and that is why it is useful to recognize
the tone of miss bedded places, it fasten the process (it allows it in
fact)

The problem with these sensation driven tricks is that your feeling
und understanding of what goes on may be immediate, after the second
or third time you lift the balance rail , the sensation change as your
perception.

And that is the same for all sensation driven method, they can only
work if you are enough used to them, and if we can assume that what we
feel is right.

That is why I believe they may be backed up with a clear understanding
in the 2 sides of the brain, of what is going on (my right side need a
little oil generally ;>)

A trick I heard for old pianos that don't have a lip under the front
rail (undersize flat = difficult to bed) , a friend of mine use a
cheap electric plane with carbure blades, and makes a lip , he say me
that the blade is harder that the base of the pins, and a very small
recess is enough. Then you can bed the remaining 2-3 cm more easily.

I installed glide bolts on a grand Bosendorfer where that was totally
warped because of many winters exposed at 20 cm of the the heat.
Indeed the glide bolts can't be tuned as much as with a Yamaha or a
Steinway, but they helped me to have the regulation done (and they
changed the tone of the piano too, it is now possible to play staccato
easily with the piano)

For sure if too much pressure is put under any glide bolt, the frame
is too rigid at this place. To avoid this, on Steinways, the extreme
bolts are screwed a bit too much too, thus lightening and warping the
frame.

So I understand that is one of the reason why these instruments tend
be seen as curling up often (while they curl , really !) , I've seen
the tendency to put too much pressure at the end even from the
factory, as can be seen by the more paper & cardboard punching on the
left and on the right.

No undue tension is better I guess , but a good distribution of the
action weight is too.

Regards.

Isaac OLEG

> -----Message d'origine-----
> De : pianotech-bounces@ptg.org
> [mailto:pianotech-bounces@ptg.org]De la
> part de Richard Brekne
> Envoye : jeudi 14 novembre 2002 08:29
> A : Pianotech
> Objet : Re: No Glide Bolts
>
>
> Thanks Roger.
>
> I hadnt expected the answer to be quite so simple, but this
> makes perfect sense.
> One runs into the problem of flexing balance rails to some
> degree all the time
> actually. Thats the question I have had about this idea
> that glide bolts can/should
> be adjusted higher then minimal contact with the keybed as
> has been described
> lately.
>
> These two points seem to be at odds with each other wouldnt
> you say ? I mean if the
> keyframe is "jacked up" as it were, you would increase the
> tendancy of the balance
> rail to flex thus eh ?
>
> In anycase looks like I have an opportunity to learn
> something new here. Bedding a
> keyframe without glidebolts.
>
> RicB
>
>
> Roger Jolly wrote:
>
> > Hi Ric,
> >              The note adjacent to the glide bolt, will be
> very rigid on a
> > forte blow, hence most of the energy gets to the hammer
> and shank.   Mid
> > distance between the bolts,   the rail will flex a
> little, therefore there
> > will be a difference in energy transfer.
> >
> > Years ago, the action makers selected very high grade,
> quarter sawn maple
> > for the rails, so very little bedding was needed after
> the initial set up.
> >
> > The Heintzman company never used glides for eons.  I have
> never found one
> > that needed bedding. The actions are quieter, and when
> set up correctly,
> > are very responsive.
> >
> > Regards Roger
> >
>
>
>
> --
> Richard Brekne
> RPT, N.P.T.F.
> UiB, Bergen, Norway
> mailto:rbrekne@broadpark.no
> http://home.broadpark.no/~rbrekne/ricmain.html
>
>
> _______________________________________________
> pianotech list info: https://www.moypiano.com/resources/#archives
>