Restoration

Key travel in 2 segments

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mike

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Opening post by mike

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I have a 1939 Petrof, serial no. 43068; recently I had the complete key lever assemblies and rollers (Renner) and the hammers (Abel) replaced.

I have read all or almost all the discussions regarding key dip and its weight, but I still haven't understood one thing that I am trying to explain in my own words.

The full stroke to the bottom of the key is 10 mm, divided into 2 segments.

1st segment (up to the escapement?): 7 mm. weight 65 grams.

2nd segment (after the escapement?): 3 mm. weight 180 grams; to overcome the resistance of this 2nd segment, I feel a sort of 'flop'... is this behavior correct?

Thank you.

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Reply 2 by Fra

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Practically a deadlock! What does the technician who did the work say? For him, are 65 grams as repetition weight correct? Were the dampers excluded by pressing the forte pedal?

Has the graphite been restored? Do the repetitions have the roller of the correct size? Is the distance between the roller and the pivot of the stiletto forcola different compared to that of the original repetitions?

How was the regulation of the escapement and the hammer drop performed?

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Reply 3 by torrese

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casorate sempione varese

Dear Fra, why pose questions, seeing as you consider yourself quite "streetwise" in this field of mechanical regulation, instead why don't you explain to us mere

mortals how things stand...

greetings

saverio

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Reply 4 by Fra

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Questions, as you call them, are used to understand what has been done; otherwise, how can one understand what the problem might be? Do we just guess? There is a new hammer, so scenarios can be different; before writing sermons, one needs to understand better! Lots of theory, but if in practice nothing works... well.

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Reply 5 by pianoexpert

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I assume this hammer weight is heavy... a bit too much. This can generate a greater downward weight. One must also check the friction of the center pins. Then, verify all the regulation specifications as well.

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Reply 6 by Davehammerklavier

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149

Dear friends, don't alarm Mike... In my opinion, he simply measured without raising the dampers...

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Reply 7 by Fra

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Ok only he knows this, in fact I asked.

The 65 grams remain anyway and those are what's needed to make the key move.

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Reply 8 by mike

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Bologna

Yes, in effect I hadn't lowered the sustain pedal; the weight is now around 60 g and all in all I am quite happy with it.

The hammers are a bit larger (11mm instead of 10.5mm) and therefore slightly heavier, but in exchange they strike the strings more effectively.

From your responses, it seems I have understood that the weight of the last segment before reaching the bottom of the key is not very important, and mine is acceptable.

I thank everyone for the replies.

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Reply 9 by pianoexpert

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I wouldn't want to be boring and pedantic, especially after having edited a Tutorial on the subject. I would like to try, without becoming unpleasant, to insist on the examination of the "patient". Even in Medicine, some doctors get "fixated" on one aspect of a symptom and do not take into consideration—sometimes only by luck—other causes that could generate the disorder and/or the disease. Then... someone comes along who prescribes all the tests and a certain number of investigations before formulating a definitive diagnosis. My wife went to 5 (five) doctors for her cough. They all prescribed antibiotics and cortisone... but she got worse; at night, she had actual episodes of choking. So, as a last resort, we went to our ENT... who prescribed some tests that unequivocally proved it was a simple case of nocturnal gastric reflux.... naturally, all the other prescribed drugs only made the situation worse!!!

Well, I am using this slightly boring little story to reiterate that even with our beloved "patient," one must follow a very precise protocol.

1) verify the friction of all the mechanical forkeys and the escapement uprights. Also verify the mechanics of the dampers (including sliding gaskets)!!!!

2) Therefore, if the frictions are correct or restored according to the usual values, we can proceed to talk about something else

3) In the replacement of the wippens, the rollers must be of identical size.

4) The hammer heads must be identical in shape and weight (compression density) to the originals (never throw away the original samples!!!!!!!!!!!!!), as must the tails be of the same type.

5) Then also verify the keyboard slots: that the sliding is smooth.

6) An initial regulation of the action is necessary, perhaps preceded by a pre-regulation of the alignment of the parts of the repetitions (cavalletti).

7) Finally, we can measure, with dampers raised, the let-off and return weights of the keys.

8) proper control of the key dip and the general alignment of the keyboard are also very important, as is the lifting point of the dampers.

I hope I have been a little useful, clear enough... even if a bit boring and assertive!

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Reply 10 by Davehammerklavier

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Far from being a boring and assertive Mr. Maestro. On the contrary, it is always a pity to have to hear stories of medical misconduct and various human blindness.

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Reply 11 by Fra

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But if you are happy with it, don't obsess over the grams and just play; three grams more or less vary from day to day....besides, the felt has always been heavier than normal for me...long live a hammer that hits the chorus well (correct observation)

Ciao

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Reply 12 by Davehammerklavier

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149

10.5 on the cantabile was a bit tight... currently, among the main brands, no one uses it anymore, except on the bass notes.

Regarding weight, 60 grams is not excessive and I would evaluate the inertia on the key return, looking at how many grams the key tends to rise back up.

If everything is in order, removing 10 grams with a lead weight is an afternoon's job (allowing for an alert and competent technician).

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Reply 13 by mike

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Bologna

I thank Maestro Ferrarelli for the review of the lesson (repetita iuvant!) I am building an extremely interesting culture that was absolutely unknown to me until this moment.

However, a few questions occur to me spontaneously:

- How much would such a meticulous and scientific intervention cost?

- How many technicians would be able to perform such a job?

- Are hammers of the same shape and weight as the originals available on the market?

Thank you once again infinitely.

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Reply 14 by Fra

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I continue not to understand whether the piano has problems or not.... 60 grams for a grand piano is a completely normal touch weight. Why do you want to change the hammers if they are new?

Is it a piano for amateur home use or must it go into a concert hall? The cost of interventions and the demands must be contained and not exceed the value of the instrument.

It is still an old Petrof...

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Reply 15 by Davehammerklavier

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There is a healthy and simple rule in these matters: never panic over 10 grams.

When replacing a hammer, especially if the original was old and/or the result of manufacturing processes that are no longer active or are obsolete, slight variations in weight are normal and practically inevitable. Consequently, replacing a new hammer in an attempt to "chase" the ideal weight objectively makes no sense.

If then the Abel hammers, as is usual with European instruments, are not satisfactory as hammers in themselves, that is another matter...

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Reply 16 by pianoexpert

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Personally, I find the Abel hammers excellent. The company produces identical hammers based on a sample. As for the work, the indicated sequence can very well be performed; I would say it is mandatory. I disagree slightly with minimizing a 10g difference, which I find considerable. I hope the old hammer weight scale has been set aside. Adding lead is not a good procedure. It would be better to intervene on the hammer tails to get closer to the original weight and inertia (but first, check the friction, otherwise everything is skewed!!!!!!)

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Reply 17 by Davehammerklavier

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149

If I had to mention a topic, in the trade of piano components, that stirs my ancestral primate fear,

i would say "the identical custom-made hammer".

Two people can resemble each other, even appear identical to the eye, in height and weight, even be twins, but what is "inside" or what happens at a cellular or neuronal level cannot be seen with the naked eye or through an aesthetic judgment.

The same applies to piano hammer felt (martelliere), which are devices more complex than one might believe.

From my unimposing observatory, I have never found a well-sounding, performing European piano prepared for a concert of objective importance (for village festivals or at an enthusiast's home, anything goes) that featured Abel hammers and, regarding the same exterior aspect, despite having purchased (and had custom-made several times) a large number of hammer felts from the company in question, it has never happened that Abel hammer felts resembled anything other than an Abel hammer felt, not to mention the difficulty one has with this company in managing hammer parameters (particularly weight), something which with Renner is absolutely clear and transparent.

Petrof is a European piano manufacturer that throughout the twentieth century was directly linked to Renner, and it wouldn't surprise me if Mike's piano showed a certain form of "rejection" toward the Abel transplant.

Regarding weight, here too, there is a problem if one's first thought is an approach directed at the hammer tails: if these have already been correctly shaped by the technician who intervened, there remains very little margin for gain on the key. An Abel shank weighs about 3 grams, which equates to approximately 18 grams (indicatively) on the key. It goes without saying that to remove 10 grams, one would practically have to saw off a third of the tail. I fear there is no filing or shaping that can lead to a weight reduction of 10 grams on the key.

However, if one has the original hammer felt, I would eventually try to inquire with Renner, which has very precise standards regarding weights that are, unfortunately, much more random and indeterminate at the other competing company.

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Reply 18 by Fra

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266

Of course, with the slimming down of a tail even made laterally as they used to do, internally or wherever one wants, if you recover 3 grams on the key it is a lot.... moreover, three grams are simply lost or gained with the change of climate, so it wouldn't even make sense to waste hours on an intervention that isn't conclusive. Then I don't think the technician who intervened failed to prepare the tails....

If there are no major differences between one key and another and if the piano shows a certain uniformity of behavior, I even doubt that there are problems with the pins.

Not being a concert grand, even if there were minimal differences, it wouldn't be the end of the world; differences of three grams on the keys even exist on pianos fresh from the factory. In current baby grands, having 60 grams of aftertouch is quite common.

Anyway, I continue not to understand if this instrument truly has problems or if there are just doubts...

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Reply 19 by Davehammerklavier

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149

The perception of weight is also linked to the sound produced. If the hammers he has now are too soft and/or do not discharge the necessary force, he will consequently feel a disproportion between the force applied to the key (at all dynamics) and the sound emitted, which leads to a direct sensation of excessive key heaviness. Perhaps this is where Mike's doubts come from...

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Reply 20 by Fra

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266

I agree, it's a fairly common discomfort also because the number itself isn't "prohibitive".... 60 grams! If the problem lies in the hammer response and the stress-to-sound ratio, it would continue to have the same feeling even with 10 grams less...

How is the room where the piano is located?

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