hi guys, my problem concerns a Schulze Polmann upright dating back about 20 years. the piano was never used by the person from whom I purchased it, the action is perfect, the problem is that the key weight is about 140 grams, compared to about 75 of a yamaha! i checked the various frictions and there are none... but I noticed that by not letting the damper work, the key returns to weighing about 70 gr, so I believe the problem is the stiffness of the damper springs... but.... I wonder: is it possible that after 20 years instead of losing tension they have become tighter? is it possible that the manufacturer released a piano with an action harder than a Bachmann??? and then... how do I solve the problem? I tried to loosen them but they remain hard anyway... should I change them? thank you very much
This action should be examined closely. Anyway, it is probably the center pins of the dampers. I have encountered this situation on a Schulze Polmann and also once on a Schimmel upright. I would also recheck the smoothness of the hammer pins, the jack forking, and the repetitions. After all this, I would consider the spring tension and their smoothness in the small red felt seat, which can be grafitated. Finally, I would consider replacing the springs, but first I would try to discharge them again.
thank you very much... today I lubricated all the pins and decompressed the springs but the result is the same as before, perhaps the action is more agile but still very hard... the strange thing is this: in the central section, where I feel the action is hardest, there is this problem: the escapement causes the hammer to stop not at 1-2mm from the string but at almost 1 cm....I went to adjust it to the right measurement and it worked well mechanically (still a heavy action though).. well.... pressing the sostenuto pedal, the escapement pusher was not coming out correctly and the hammer would bounce (in pp) on the string.... practically, in order to be able to play pianissimos with the 3rd pedal, the only way is to adjust the escapement to almost 1 cm from the string....what should I do?
Dear Davide, what did you use to lubricate the pins? (I am against using lubricants) From the other data you provide, it seems clear to me that the key dip is insufficient in relation to the hammer let-off stroke, which should be about 45mm.
Sequence of adjustment:
- determination of hammer-string distance
- regulation of the height of the repetitions (piloti)
- regulation of the escapement point
- increase or decrease of the key dip
- regulation of the check (parata)
- regulation of the spring levers (bretelline)
- regulation of the dampers lifters (cucchiaini)
I insist on checking the pins of the entire action, which must be replaced and oversized (by a competent technician using good pins and non-conical reamers)
Dearest Paolo, the key dip is exactly 1 cm....but evidently I must adjust everything else...I will try with the order you indicated to me...so far my adjustment order was
Key dip
regulation of the repetition (pilota)
hammer-to-string distance regulation
escapement regulation
repetition lever (paramartello) regulation
spring (bretelline) regulation
dampers regulation
rregarding the lubricant, it is a German "dry" oil, specifically for piano mechanics....
rregarding my location, I live near Milan and am a small musical instrument retailer and piano teacher...and I manage to do some small technical work personally...the piano in question belongs to one of my clients...I consider the idea of increasing the pin size to be valid, although, anyway, I do not notice any particular friction when removing the dampers...but I defer to your professional experience (which I highly respect, as well as respecting you as a person). I will keep you updated...
In the sense that when the pins are replaced, they must always be oversized, after boring out the cashmere. Oil, unfortunately, can give good results in the moment (including Ballistol) but later it could harden the pins even more... anyway, we shall see. Good luck with your work
Yes, alright. Teflon powder, the only lubricant to use, can help, but not solve it. All the mechanical pins must be checked and ABSOLUTELY DO NOT LUBRICATE THEM. Oils and lubricants do nothing but clump up and make the smoothness IRREVERSIBLE. The only thing is to check the friction and see how to eliminate it.
I am joining this old thread to ask a question about how the key dip weight (and consequently the let-off/return) should be measured in order to have a unique reference, specifically how and in what position the force must be applied (I would imagine at the end of the key, corresponding to finger pressure).
I am asking this because the Petrof manual does not provide indications on the correct dip weight but only performs a check of the dip measurement with a special 273 g weight placed on top of the key.
273 grams?????????? No!!!! That is a weight used to determine the correct let-off distance (which is about 10mm)!!!!! The tool is used to make the key gravitate with uniform pressure to precisely measure the distance. It has nothing to do with measuring the key weight (downweight) and the repetition weight (upweight)!!! To verify the latter, a weight of about 50g must be applied (but it can vary from about 52g in the bass to about 47g in the treble) without intervention from the dampers. The repetition weight, which should not be less than 20g... but even 25-27g, is achieved when the key, weighted with this mass, returns to its resting position without hindrance, i.e., with uniformity and a certain briskness.
If the downweight is excessive and the repetition weight is too low, then we are dealing with friction higher than tolerated values, and the pianist will feel a keyboard that is hard and unresponsive in repetition. Only the replacement of the action pins can restore the correct smoothness to the instrument. NO LUBRICANTS!!!!!!!!!!!!!! (The work on the pins must be done with expertise: oversized pins and honed bushings using straight reamers. If a grease lubricant has been applied, the bushings could be compromised!)
If the downweight is too low and even the repetition weight is minimal, then there was an error in the keybed leveling and/or replacement with a hammer rail that is too light. It will therefore be appropriate to reconsider the regulation, always verifying the proportion between the two weights: downweight and repetition weight.
Hello, I am an older beginner and I am studying on an upright piano that is a century old and has been stationary for over 20 years.
I have seen your beautiful videos on piano mechanics on YouTube, for which I thank you sincerely.
I would need some advice regarding a problem with key hardness in the low notes (those that sound one or two strings) which makes the work of my left hand very tiring.
By testing empirically, the weight necessary to depress the keys results in needing only 6 or 7 €1 coins (about 50g) for the "soft" keys, while for the hard ones, 11 or more are needed. Pressing the sostenuto pedal, the hard keys soften a lot and the others slightly.
I noticed that the dampers of the hard keys rise immediately along with the hammer, while those of the softer keys rise when the hammer is halfway through its stroke or beyond.
Pressing the sostenuto pedal slowly, the dampers of the bass notes rise immediately and the others only by pressing the pedal further down.
It seems to me to understand that the problem lies in the dampers acting too early, weighing down the mechanism.
What could I do? Should I work on the capstans (is that what they are called?) and ensure that all the dampers rise with the same delay?
The influence of the dampers on hardness is nonetheless complementary. I believe that even here, the mechanical pins should be restored, a job that restores "youth" to the piano!!!! I REPEAT: no lubrication. This would make the "clumping" of the fork gaskets irreversible, meaning they would no longer slide on the pins. One must also begin to evaluate the keyboard gaskets and pins. Poor sliding—the gasket not sliding—causes the key to suddenly lock when subjected to lateral stress, i.e., with a non-perfectly vertical depression, creating significant discontinuity in the movement of the entire keyboard. This, added to the inefficiency of the fork pins, renders the action unusable. Regulation comes later. Attention: the pins, without the use of ANY lubricant, must be replaced by reaming the gaskets with cashmere using STRAIGHT reamers! And they must be oversized by one size, so as to ensure that the pin is firmly fixed in the wooden part!!!!! This work must be done by an expert. It involves the disassembly and reassembly of the entire action. When replacing the pins, the friction coefficient expressed in gr. is measured with a specific device: from 3 to 5. The straight reaming of the hole allows the part, hinged on the fork, to be "firmly held" despite the modest friction.
P.S. Naturally, the damper pins must also be checked.... which, as I understand it, change the weights significantly when the pedal is raised. Then also check for any excessive load on the damper springs themselves.
Thank you Paolo for the prompt response and for the good advice.
Yesterday, after writing to you, I tried to adjust a spoon that pushes the damper of a "hard" key by pulling it back slightly in order to delay its engagement. The result was good; the key was softer. I tried to do the same work on all the keys of the low notes and now the keyboard is more homogeneous and I struggle less to play with my left hand. Naturally, the defects on such an old piano are infinite and I only notice the most macroscopic ones.
A radical job done by a qualified technician would be needed, but the costs would be very high and I don't think it would be worth it.
I would need some clarification regarding the regulation of the dampers' spoons and springs on an upright piano.
It is not clear to me whether the dampers should start rising as soon as the key is depressed, therefore in sync with the hammer's onset, or if there should be a delay, and if so, how much.
Some springs are harder than others. How do you proceed to discharge them?
The damper, adjusted normally (neither advanced nor delayed), should rise at the halfway point of the hammer's stroke. Before touching the springs, one must check if the pins in the damper mechanism have too much friction. If so, everything feels stiff and to overcome this friction, the springs are forced to work harder. Some manufacturers also tension the springs a bit more to favor damping.
The stiffness of the entire mechanism depends on the sum of the pin frictions, which must be within certain values, neither more nor less.
