Hammers strike the strings multiple times when slowing down the escapement halfway through the key stroke

Forgive me, I forgot to tell you that the hammers have been shaved down by about 4mm.

This could probably also be the cause.

Paolo, I await your expert opinion.

Thanks again

The wippens are too slow. If possible, increase the pins. As far as the measurements are concerned, I believe there is some error. Double-check carefully. Generally, with a hammer-to-string distance of about 45mm, a key dip of 10-10.5 mm is sufficient, setting the let-off at 3 mm. The hammer rebounds because the repetition lever cannot escape under the capstan. Have you perhaps shifted the alignment of the rail bars and/or the hammers?

First of all, thank you for the answer.

I have rechecked the measurements.

So:

The hammer/string distance is not constant: it is 45mm on the lowest A, while it is 50mm on the highest C. For the middle notes, it gradually increases from the bass towards the treble.

As far as the aftertouch (affondo) is concerned, I measured it on the E where the central section of the hammers begins, and it results in 12mm.

In effect, the escapement manages to escape from under the capstan, so much so that if I play with a constant descent of the aftertouch, it works well both with pianissimos and fortissimos. The problem arises if I vary the speed of descent; for example, pressing forcefully until halfway through the aftertouch, I get the first percussion on the string, but if I then continue to descend, it strikes again.

In truth, I have disassembled everything. Capstan by capstan, bridge by bridge, hammer by hammer, nut bar, hammer rest bar!

And then I reassembled everything after slightly reaming all the capstans. What do you mean by the alignment of the bridge bars and/or the hammers? I probably moved that as well.

I mean the ones that carry the jacks and the hammers. A 12 mm let-off seems excessive to me. Also, keep the hammer-to-string distance uniform at 45 mm. It could be that the parameter gets too close because of the 12 mm let-off, which is certainly excessive. Try 45 and 10-10.5. In fact, I have this suspicion because playing with a "constant descent," the notes are right at the bottom of the key and the parameter hammer doesn't advance much. By insisting on pressing, the parameter hammer brings the hammer closer to the string, making it resonate or even, in some cases, stopping the sound by resting on the string. I believe this could be it.

Hi Paolo,

i did as you said.

I brought the let-off depth to 10.5mm and standardized the hammer/string distance to 45mm along the entire keyboard.

What I observed is that in order to have a let-off distance of 3mm without interference between the pusher and the capstan when the hammer is at rest, it is necessary to bring the hammer/string distance to 40mm by adjusting the wippens accordingly. The alternative is to give up on a 3mm let-off and instead set it to a value of 7 or 8 mm. With such a value, the pusher escapes correctly from under the capstan.

At this point I ask: is it better to have an 8mm let-off with a hammer/string distance of 45mm, or to have a 3mm let-off with a hammer/string distance of 40mm?

Furthermore, is it possible that the geometric shape of my action's capstan (Renner) does not allow me to have a let-off distance of 3mm? I should mention that the piano had been designed to have the damper cloth, which I removed specifically to achieve the smallest possible let-off.

Thank you again Paolo for your availability and promptness in your replies.

check the small escapement lever rest cushion. It might be too thin. All of this seems strange to me. Surely someone has altered some distance which caused the alteration of the mechanics' geometry.