hammer alignment

raffaello56 wrote:

Good evening,

I am facing the action of an upright piano, with the hammers oscillating, so it is necessary to tighten the screws of the capstans;

question: What system do I use to fix all the hammers at the same distance? Do I need to get (build) a jig?

Thank you

I didn't quite understand the question; do you perhaps mean the spacing between the hammers? Laterally?

In this case, there is no jig; one must stand in front of the piano and first evaluate its construction. If it is a model that uses agraffes, the string positions are fixed, therefore the hammers must be centered on the strings. It is possible to space the capstans after tightening the screws with a flat tool that is made like a spatula but thinner; by bringing the hammer closer to the string by hand, you can check if the position is correct.... obviously, upstream, the hammers must run straight, parallel to each other. If this does not happen, a correction shim is necessary (to the right, to the left, under the capstan screw depending on the case).

If instead the construction of the upright includes a compressor, the strings can be spaced over the hammers; obviously, one must ensure that they run correctly, that they are "optically"—if you'll excuse the term—spaced in a regular manner.

If instead you are referring to the hammer-to-string distance, then the uniformity of this measurement depends on the rest rail cushion. In an upright, the hammers rest on the cushion of the rest rail which, if its thickness is not regular (perhaps because it is new), results in a non-uniform alignment of the hammers at rest; one must then proceed to iron the cushion. You can use a screwdriver as thick as a stiletto, slightly warm heated with a kitchen stove to use a home method (please avoid burning the felts; the same rule applies when ironing wool knits) to accentuate the indentation created by the stiletto itself for the hammers that end up further forward than others...

Obviously, the regulation of the pilot and the play must be reviewed. The hammer-to-string distance is regulated by inserting shims under the mobile rail of the keybed if it needs to be shortened, or by acting with shims under the screws of the rail itself if it is fixed (there are now uprights with a single-string pedal where the action translates).

Do you understand that saying "upright piano action" unfortunately does not identify a unique way of proceeding? If you were facing, for example, an early century Steinway Vertegrand, where the capstan for dampers and hammers is double and single, performing the centering would be much more complicated than what was described.

Is everything clear or do doubts remain?

Everything is perfectly clear.

I was referring to the first part of your response anyway, but thank you for the precise explanation.

Raffaello

Ok, tighten the screws after unhooking the straps, taking care to keep the pusher all the way back....if you find the hammer centering while tightening the screw it's better, and don't do like many who stick the screwdriver in to find the screw by forcing the pusher to the side. Tighten them well but without choking them, they are still wood screws and it is easy to ruin the threaded seat, especially if the instrument is old.

Ciao.

I add nothing more to Giovanni's competent response. Bye to both of you

Hi Giovannig, why don't you write your own book on piano repair and maintenance? I would be your first buyer.

THANK YOU and big greetings.

Saverio

Thank you all.

Raffaello