Glide bolts

[antares]

Kawai's suck, so forget about it.

IO


friendly greetings
from

Antares,

Amsterdam, Holland

"where music is, no harm can be"

visit my website at :  http://www.concertpianoservice.nl/
and the website of :  http://www.grandpiano.nl


> From: "Isaac OLEG" <oleg-i@wanadoo.fr>
> Reply-To: oleg-i@wanadoo.fr, Pianotech <pianotech@ptg.org>
> Date: Mon, 28 Oct 2002 20:19:48 +0100
> To: "Pianotech" <pianotech@ptg.org>
> Subject: RE: Glide bolts
> 
> Hi ! what a complete treatment of the operation !
> 
> What happens with repetition when a very little too much pressure is
> used. I Just come from an action that loosed its responsiveness after
> a 2/12 turn was given (Kaway RX2 new). just tried to reach the 65 mm
> height (from 64.5) and was obliged to go back, as things where getting
> bad for repetition.
> 
> I suspect that the back of the frame was not seated firmly enough
> then, but it was not visible (no hammers jumping when playing staccato
> chords for example)
> 
> These grands seem to like to have really not a lot of pressure, or is
> it a matter of tone (voicing) that links to bad repetition ?
> 
> Thanks for any idea.
> 
> Izaac O Z
> 
> 
>> -----Message d'origine-----
>> De : pianotech-bounces@ptg.org
>> [mailto:pianotech-bounces@ptg.org]De la
>> part de antares
>> Envoye : lundi 28 octobre 2002 14:54
>> A : Pianotech
>> Objet : Glide bolts
>> 
>> 
>> 
>> 
>> 
>> 
>>> From: Richard Brekne <Richard.Brekne@grieg.uib.no>
>>> Reply-To: Pianotech <pianotech@ptg.org>
>>> Date: Sun, 27 Oct 2002 23:31:11 +0100
>>> To: Pianotech <pianotech@ptg.org>
>>> Subject: Re: SV: OT - Treating Centers with Alchohol
>>> 
>>> What about those glide bolts ?? :)
>> 
>> Awright bud,
>> 
>> Key frames tend to move, due to changes in humidity. I have
>> seen this often
>> with especially larger instruments. One season key dip is
>> too deep and then
>> the next time it is too shallow. It also happens many times
>> that the left
>> and right ends of 'certain instruments' curl up, which is
>> very annoying, the
>> more so, because it still happens and they still have not
>> changed their
>> design.
>> The invention of glide bolts did not end these complaints
>> but made the key
>> frame more stable and gave the technicians the possibility
>> to quickly alter
>> key dip and key height which was not possible before in
>> such a short amount
>> of time.
>> 
>> As older key frames tend to curl up and thereby cause
>> instability and noice,
>> the idea was to create an arch in the new frames. An arch
>> from North to
>> South and in the case of Steinway also from West to East to
>> accommodate the
>> arch of the soundboard.
>> When we put a modern key frame on a straight table/bench
>> without keys and
>> action, we will notice that the arch is higher and that the
>> glide bolts are
>> not in contact with the surface of the bench/table.
>> As soon as we put the keys and the action back on the key
>> frame, the arch
>> has flattened and the glide bolts may touch the surface underneath.
>> Because the glide bolts are screwed in the balance rail, we
>> can screw them
>> up or down, according to what is necessary.
>> All factories have specific measures for their key height
>> and this means
>> that every instrument will have about a standard amount of
>> paper punching
>> under balance rail punching and front rail punching, to get
>> the desired key
>> height and key dip.
>> With the glide bolts we can alter key dip and key height,
>> but there is more
>> to it.
>> A glide bolt has two other options :
>> With the glide bolt we can also control the pressure, put
>> onto the key bed
>> by the glide bolt in combination with the weight of action
>> and keyboard.
>> If too much pressure is applied, the key frame is probably
>> pushed up too
>> high, causing all kinds of regulation problems, but at the
>> same time the
>> quality of the tone will change.
>> That is option number 2 : the glide bolts have more or less the same
>> capacities as a tuning fork.
>> We can not hear the vibes of a tuning fork if we don't put
>> it down on an
>> amplifying object. By pressing down a key and making a tone
>> we create a
>> vibration transmission between our finger and the generated
>> energy of string
>> and sound body which is the sound board and actually the
>> whole instrument.
>> The less deviation in the energy transmission, the more
>> energy is being
>> transmitted and the more power we literally feel in our
>> finger. With less
>> deviation I mean : a well regulated action, a well tuned
>> unison and, very
>> important, a firm front rail punching.
>> A less firm front rail punching sucks energy, creates a
>> very  'soft landing'
>> of the key and thereby causes an unclear and diffuse after touch.
>> 
>> By regulating the key frame and the glide bolts, which is
>> the beginning of
>> the regulation process - with the cheek blocks fastened
>> please -,  we can do
>> a few very important things at the same time (in Holland we
>> say "kill two
>> flies in one stroke') :
>> We check the key dip first and measure the key height (from
>> the key bed to
>> the underside of the key top covering).
>> If the key height should be 64 mm but is (on average) 63.5
>> mm we should turn
>> the glide bolts just a little to the right to bring the
>> balance rail up a
>> bit, but before we do so, we measure the key dip.
>> As the key height is too low, the key dip 'should' be too
>> shallow too.
>> If that is the case, key dip is for instance 9.3 mm, we can
>> be assured that
>> we do the right thing and we start by turning the middle
>> glide bolt just a
>> tiny bit to the right while at the same time feeling with
>> our left hand (if
>> we are right handed) the movement in the key dip measuring block.
>> A quick short turn is usually enough.
>> We repeat this process with every glide bolt, but with the
>> one most on the
>> left we have to depress the left pedal as the action will
>> be obstructed by
>> friction between action and the left side of the rim.
>> When we 'think' that on every place of the keyboard the key
>> height and the
>> key dip are corrected we tap with protruded fingers (or the
>> side of the
>> hand, or a fist) on the balance rail near every glide bolt
>> to make sure that
>> every glide bolt makes a firm contact with the key bed.
>> This is not as easy as typing in these words. It needs a
>> lot of practice
>> before we do it right at once and actually a seminar on
>> this subject should
>> at least take a few hours.
>> 
>> OK...after we have made sure that every glide bolt hits the
>> key bed and key
>> height and key dip are still what they should be, we should
>> take care of
>> eventual glide bolts on the under side of the key frame,
>> which is the case
>> with Yamaha grand pianos.
>> On the left side we will see two glide bolts in two
>> sections, which we were
>> not able to service from above as there is no place to
>> stick them through
>> the keys. Yamaha sells a special tool for glide bolts with
>> a possibility to
>> grip and screw the bolts underneath. By pulling out and
>> lifting up the
>> keyboard and action, be careful not to damage the piano
>> with the drop
>> screws!
>> Again we tap for rattling and when we are sure the work has
>> been done, we do
>> a 'weighing test'. If it is an instrument with a hammer
>> rail which is easy
>> to lift by hand, like a Yamaha, we lift the hammer rail
>> with our left hand
>> and knock on the balance rail at the same time to find out
>> how easy or
>> difficult it is to create a knocking sound. between the
>> lifted balance rail
>> and the key bed. It should not be too easy, and it should not be too
>> heavy.(this is something I can only demonstrate during a seminar)
>> The weight should be the same overall but we can can choose
>> for a difference
>> in pressure/weight in regard to 'tone'. We will notice that
>> when a lot of
>> pressure is applied the tone will have a sort of
>> 'grounding' quality. We can
>> hear the same if we pit a tuning fork - lightly - on a
>> wooden surface or
>> press it down very hard. If we press it down very hard the
>> tone will change
>> to what I call this 'grounding' quality. (I am sure  a
>> native speaking
>> American or other English speaker will find a better word)
>> 
>> When all this work has been done, there is a final test :
>> 
>> We bang on the piano (on the wooden beam that is situated
>> against the iron
>> frame and directly over the keyboard, what is the name?
>> please) and listen
>> for a rattle.....
>> If we hear a rattle we put one finger lightly on each bolt,
>> ubtil we have
>> found the one that causes the rattle.
>> Tighten bolt, end of story.
>> 
>> 
>> 
>> friendly greetings
>> from
>> 
>> Antares,
>> 
>> Amsterdam, Holland
>> 
>> "where music is, no harm can be"
>> 
>> visit my website at :  http://www.concertpianoservice.nl/
>> 
>> 
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