Damper spring replacement

the springs have a certain diameter that must be respected. You must unscrew the screws and remove the two pieces from the bar they are fixed to. If you remove the upper part of the mechanism, you will immediately see where you need to unscrew. Then you need to see how the springs are hinged. Generally, they rotate on a passing cord that must be removed with an extractor and re-threaded. The best thing is to take the two disassembled parts to a workshop. If you want, you can also send them to me... it will only take me a moment... see if there is someone coming towards Rome south.... who is returning back up..... Sending them by courier costs too much.... anyway, you can look into it. In any case, keep the broken springs. They are needed to determine the diameters. See if you can resolve it. Otherwise, send them to me. But how did they break????? and are they flat or wedge-shaped dampers?. In the second case, I have to be careful to reassemble them correctly... otherwise they will no longer dampen annoyingly.

P.S. check if they have simply slipped out of their seat

Regards Paolo

Thank you very much Paolo, for the splendid explanation...Over the weekend I hope to manage to dedicate some time to understanding what I can do...

Unfortunately we are quite far apart, I live in Veneto, between Padua and Bassano del Grappa, so I will have to adapt by trying to manage on my own or find someone in the area who can help me. If I could already disassemble them and take them to someone (there are those who do piano maintenance here in the area) I think I would at least save myself the trip.

Thanks again and I'll let you know

greetings

Tommaso

Good morning.

I own a Petrof P 125 II piano with Detoa action.

Unfortunately, it has remained unused for several years.

I asked the Petrof company for information regarding the touchweight.

The company provided me with a document explaining how to perform a damper spring test.

I performed the test and recorded the weight in grams of the spring tension.

From the weights recorded, I found that the springs are too hard in the bass section (from 30 to 46 grams over) and loose springs (from 10 to 20 grams under) in the treble section. For this reason, I would like to replace them all.

My questions are:

1) Can time and disuse have made the damper springs hard or soft?

2) If I replace the damper springs with new ones, obviously respecting the diameters, will I obtain the correct tension, or must they still be tested and potentially adjusted?

I don't think you will solve it by changing the springs. The spring is chosen by the Manufacturer based on the weight of the damper head. In some uprights, they turn out to be a bit hard. You can try to unload them until you are satisfied with the sound damping capacity.

Maestro, good morning.

I am asking you, as you surely have a lot of experience.

In the Petrof document that the manufacturer sent me, I read that the weight required to lower the dampers by 5mm from the strings must be:

80 g. bass;

70 g. middle;

55 g. treble;

I have a spring, just to name one, that needs 140 g to lower by 5mm.

60 g. more than necessary.

It seems that the period of disuse (we are talking about over 10 years) has hardened them in the bass and middle sections while loosening them in the treble.

Dato che sarebbero tutte da regolare per portarle a questi valori mi chiedevo se non fosse più semplice sostituirle tutte.

Since they would all need to be adjusted to bring them to these values, I was wondering if it wouldn't be simpler to replace them all.

Are the new springs already calibrated or do they still need to be adjusted?

If you have the experience to do it, OK. Keep in mind that the dampers need to be recentered

Thank you very much, Maestro.

Unfortunately, around our parts, prepared technicians are hard to find.

At first, I desisted from putting my hands on it.

I looked for a technician to have the action refurbished.

Technician paid profusely without having obtained any substantial improvement, except for a slight improvement. Anyway, the story is long.

(I have already spent so much on this piano without satisfaction).

No experience.

I am just a DIY enthusiast.

They don't seem like very complicated interventions to me.

This forum is a resource.

The Petrof company is sending me useful information.

I will do most of the work myself.

I will let a tuner handle the regulation.

The only positive side of this experience is that I am discovering a fascinating world.

GuidaEnzi wrote:

On 26/9/2024 at 09:31, GuidaEnzi said:

The company provided me with a document stating how to perform a test on the damper springs.

I performed the test and recorded the spring tension weight in grams.

Can I know what kind of test this is?

Thank you

Of course.

The test must be performed with the action (mechanical part) removed from the piano.

The action must be placed on a horizontal surface so that the dampers are positioned at the top.

The test should be carried out using a tool that has a hook at the end and can be adjusted to 3 weights (80, 70, 55 g).

Upright Damper Spring Tension Tool

By placing the tool on the damper lever at the point closest to the wooden part, the latter must descend by 5mm.

(80g for the bass + 5/6 dampers beyond, 70g for the middle, 55g for the treble)..

If applying the correct weight it does not descend, it means the spring is too stiff; if it descends more than 5mm, it means the spring is too loose.

Then there is the whole matter regarding the regulation of the springs.

I built a tool myself which I used to:

1) measure the DownWeight/UpWeight of the keyboard;

2) determine the weight necessary to lower the damper by 5mm.

In my case, all springs except one need adjustment, so I was considering replacing them all.

In the hope that the new springs will give me a weight close to the optimal one.

PS. I have sent you my contact details in private. If you want, we can talk and meet up.