I have a few questions regarding the regulation of a 1952 Schulze & Pollmann upright piano with Renner action.
The tips of the hammer rail springs (bretelline) are very delicate, so much so that while removing two pushers to unlock them, they crumbled away from their stops. When I go to perform the replacement work, how are the new tips mounted? Are they glued with a little Vinavil? First, I would like to try soaking the tips in water and Vinavil, similar to repairing woofer cones: could that work?
Slow pushers: as per your punctual response in the previous thread, these are caused by the pins. Since we are talking about two sluggish pushers, how do I restore them to their original mobility? Do I extract them, clean them, and put them back? Do I slightly enlarge the hole? I would like to avoid the solution of changing the pin diameter because I don't have any technology to redo the hole, etc.
My last doubt is about the hammers. They are over 60 years old but are not very marked, almost not at all. I am missing the meaning of hammer voicing performed by puncturing them. In what way does it voice them? Does it soften them so that their impact with the strings produces a different sound? A more voiced one? Is that possible? Also, is it worth it, or is it a fine operation for high-level pianos played at high levels, or is it an operation that brings audible improvements even to casual players? Somewhere on the forum I read that someone even hardens them with specific liquids... I don't understand the logic....
Let's take it step by step. For the strap ends, there is no problem. You can remake them with a very light leather or with a colored fabric. The purpose of the ends is to reinforce the hole that undergoes stress during the hammer return. Diluted white glue (PVA) can work fine.
For the pushers, try to extract the rest and "massage" the pusher back and forth, as if you wanted to "warm up the part." In this way, the part of the pin located in the gaskets is stressed and warmed, which can help restore the correct friction. Some technicians pull the pin out of its seat just a little bit and warm it. This favors the movement of the pin because... naturally, the heat causes it to increase in gauge... but be careful... the pin also widens the central seat where it must remain firmly fixed in the wood. When it cools down, it remains too loose even in the internal part and could eventually pull out of its seat (in fact, the pin must be very firm in the center and easy in the gasketed holes. This is why when replacing them, you increase the size!). No pulling out, no cleaning, no lubricating. Nothing! If you don't solve it... the pin must be replaced!
The Hammers. After so many years, the hammers have hardened and are no longer elastic. They aren't even "available" to be voiced. You won't get good results by pricking them. Furthermore, this is the intervention that requires the most experience. Consider that in a factory, the person who voices the hammers is paid more than other technician-workers. On new hammers, you can use or not use the hardening impregnator, yes, on the hammers, which then, once voiced again, acquire greater power. Some manufacturers impregnate and some do not. The voicing intervention is complex and is not limited only to "pricking." Well-voiced hammers acquire a beautiful sound, and the difference from before the intervention is audible even to non-expert musicians. It is about making certain areas of the hammer more or less elastic so that the impact with the strings allows for the generation of the right harmonics that "dress" the beautiful sound.
The beautiful sound does not depend only on the hammer action, but also on the age of the strings and the charge of the soundboard. The refinement in the design calculation does the rest.
After dismantling the pusher, I noticed that it now rotates well on the pin....and yet the hammer defect, where it does not return properly to its resting position, remains: if it is not the pusher pin, is it the pin where the hammerlet rotates? Or perhaps I kept the strap too loose?
The pins rotate but anyway, even with the pusher disassembled, it returns more slowly. At this point I think it is the pin of the nut fork, i.e., where the hammer moves. But does the hammer return to position thanks to its own weight, or does the spring mounted on the nut act, which is attached to a thick cotton thread? Or is it just the strap that brings the hammer back? If I pull it too much, however, I won't solve anything.
Dear Maestro Paolo Ferrarelli, why don't you try to write all your remarkable experience into a book? You would make us all very happy and I would be the first to buy it.
If everything could be learned from a book, we would all be fine. In reality, I personally believe that several good books already exist that provide information on the subject. Mine would be one of many. Knowledge, however, is formed not only from information, but from experience gained, and that belongs to each of us. Information + experience = knowledge. One of the daring goals of this forum is, among others, to encourage, where possible, technical and musical experiences, following the information provided. It is evident that even this does not replace the competent intervention of a professional technician or an experienced musician teacher. So, dear Saverio, although I thank you for the invitation, which I interpret as a token of esteem, I suggest you consult existing reference books of fundamental importance. The Reblitz is one of these. The language is very easy to understand. It is written in simple English and talks about a subject known to us. This is an advantage. Marcello Sorce Keller, great Ethnomusicologist and pupil of the great Carpitella, once my Ethno teacher, suggested that I read the subject I knew directly in the language. I, who am bad with languages... actually terrible, discovered that reading a subject well known to me in a language not well known to me... is possible! It is thanks to my friend the Professor who gave me a little Anglo-American booklet written by a musician and directed at country musicians who wanted to learn the first rudiments of Music (figures of value, rhythm, etc.). It was small, pocket-sized, and the title was ironically American. Translated, it sounded something like this: "chicken feet and fly droppings," meaning the notes.... it was very useful to me.
I should have solved the problem. Looking closely this morning, I noticed that the escapement was not completely releasing from its seat but remained there. At first, I adjusted the button, but then I found it was the green hammer stop. I don't understand the mechanics of it, but now, by moving it a little, it works. The escapement follows its normal course and the hammer returns as fast as the others. I fixed the broken tips with electrical tape, and it works very well. The only thing is that I need to buy a red one....for pure aesthetic reasons. Conclusion: books aren't enough, what's needed here is an apprenticeship....if I had seen it being done, I wouldn't have wasted hours. Thank you
The green hammer rest felt should not be touched unless you want to change the hammer-to-string distance. That being said, if the escapement does not return under the capstan, one must adjust the key lever. It is lowered slightly by screwing it so that, with the mechanism stationary, the escapement can return without impediment under the capstan. Naturally, there is a regulation point such that even the slightest play is not felt under the key before the hammer shows signs of movement. A strap that is too tight can alter this regulation. Attention. If you watch my video tutorials, I explain all of this.
The fact is that I had moved it to insert the tip the first time I worked on it. I don't understand the mechanics, but by moving it a little, probably putting it back as it was originally, tinkering with it now, after having screwed in the pilot a bit and adjusted the strap, it comes out of the walnut without hindrance and therefore the key returns with the correct movement. I watched the tutorial, however; before understanding it well, you always have to bang your head against it....plus it's been a few years since I studied.....
