Upright piano keyboard problem — Pianoconcerto Forum

Member

Posts: 2
City: Vigevano

June 25, 2024, 23:12

Good evening,

I own a Kawai CX5 which, after being purchased about 25 years ago, played for a few years and then remained unused for about 20 years.

A few years ago it started playing again and after several tunings it holds its tune well today, but it presents a problem of a very heavy keyboard.

I should mention that it has never been regulated and the only interventions were inserting some shims under the rail where the hammers rest to solve the problem of 2/3 keys that were sticking, and a tuning a few years ago.

Now I wonder if it is a mechanism born this way or if it requires specific adjustments.

Could it be a problem of friction due to inactivity?

Obviously, on more humid days everything gets worse, while with the left pedal (una corda) the keyboard improves slightly.

The person who handled the tuning was unable to resolve it, telling me that it is a somewhat heavy keyboard, but after watching videos of a journey inside the piano, I am starting to have some doubts.

Thank you

pianoexpert

Moderator

Posts: 3,876
City: rocca di papa

June 26, 2024, 23:30

It definitely depends on the mechanical pins. They must be restored; one must know how to intervene. The pins must be extracted, the bushings bored out, and the pins enlarged by one size. NON-CONICAL reamers must be used

Gabry79

Member

Posts: 2
City: Vigevano

June 27, 2024, 13:22

pianoexpert wrote:
13 hours ago, pianoexpert said:
It definitely depends on the mechanical pins. They must be restored; one must know how to intervene. The pins must be extracted, the bushings bored out, and the pins enlarged by one size. NON-CONICAL reamers must be used.

In your opinion, is this a job that can be done on-site, or does the action need to be removed?

In the meantime, I tried putting in some 20 cent coins and it took as many as 13 to bring the key to halfway through its stroke.

So, roughly speaking, we are at around 70 grams or so.

I will try to wait until the next tuning after the summer to intervene.

Thank you

francescochopin90

Member

Posts: 355
City: .

June 27, 2024, 21:23

If it is only a few pins, it can be done on site. But I really think that in your case the action needs to be taken to a workshop. One must also check skins, felts, etc.

pianoexpert

Moderator

Posts: 3,876
City: rocca di papa

June 29, 2024, 07:35

The action must be removed because the repetitions must also be disassembled to check the fork pins of the repetitions and the pins of the escapement uprights. 70 gr. is truly excessive.

When the friction of the pins increases disproportionately, the downweight increases significantly and the let-off weight decreases. Playing becomes an achievement!!! It is equivalent to driving a car with the handbrake on!!!!

The work on the pins is delicate. Special reamers must be used, and one must understand how much the pins need to be oversized (they must always be oversized by at least one size: e.g., from 1.30 mm to 1.325 mm...). One must understand how much needs to be reamed so that the pin develops the right coefficient of friction but is not too loose! Holding the fork steady with one finger, the moving hammer shank must not wobble; it must be very steady, ready to receive the hammer strike against the string without lateral deviations!!! Suitable extractors must also be possessed!

For these reasons and others, it is difficult to find technicians willing to perform pin work. It requires experience. Some say "just play for a while and the action will 'loosen up"'—nothing could be more false!

Therefore, the action must be disassembled on the bench and, once the work is completed, alignments must be respected during reassembly.

Furthermore, ATTENTION: do not use lubricants and/or do not try to heat the pins. In both cases, the results would be terrible!

The good news is that by performing the work correctly, the piano "comes back to life."!!!

However, the cause must still be ascertained. Check, for example, if the instrument is in a particularly humid environment. An excessive increase in relative humidity causes movement in the wood and the cashmere felts around the pins, blocking them.

Regards,

Paolo