How to make a piano keyboard

Step 3 Materials: hardware

The playing portions at the front of the keys are covered with more durable and cleanable materials than the wood used making the keyplank. The natural keys have a thin, hard material on their fronts and tops, and the sharps are made taller by gluing thick pieces of hard wood or plastic with a color that contrasts with the naturals. Sheet materials like veneer or plastic can be glued on sooner and require less work compared with individual pieces for each natural key which you can get in plastic, bone or ivory, in three, two or even one piece, in the case of molded plastic keytops. I reused old two-piece ivory from an old piano, but this makes it more difficult because each pair has already been trimmed, levelled and shaped together for the exact key they were on originally, and like the ones I used they are often discolored, worn and damaged.

Modern pianos use two polished pins running in specially formed holes to hold each key in its position and to guide its motion so that no keys interfere with each other. You can read about some methods used in harpsichords here.

The balance rail pins are usually cylindrical and rounded or chamfered at either end, and long enough to be bedded into the rail at the lower end and protrude slightly above the key at the upper end.

The front rail pins are formed so that the upper end has an oval section, so that the flatter sides present wider bearing surfaces than if they had a circular section. The lower end that is driven into the rail is cylindrical and chamfered. A lot of writers warn against turning these pins to take up play as the holes in the keys wear larger, but this is exactly why they were invented. A couple of 19th century piano manufacturers makers did the opposite, so the hole itself could be adjusted by turning a screw.

The guide holes in the keys used to be closely fit in the wood, but eventually were lined with usually replacable bushings made of resilient cloth or leather, about 1mm thick and sold cut into long, narrow strips. The fitted parts of the holes may also be made in a different piece of wood, to make them more durable as well as to reduce work, usually balance pins work in glued on key buttons, which can be prepared separately or bought ready made.

The back rail is covered with a strip of about 3mm thick cloth cut about 4cm wide so that the keys don't knock or rattle as they return to their resting positions. There is padding on the balance rail and on the front rail as well, but now usually in the form of punched cloth rings, about 1mm thick and 12.5mm diameter at the balance rail, and 3mm thick and 25mm diameter in the front, with center holes a little tight on the pins. These are usually raised above the rail with different thicknesses of the same size paper and cardboard rings, so that the keys rest and travel uniformly.

The keys will also have some sort of device mounted at the back end. My keyboard, as well as Davies', has one of the main parts of the action glued onto the keys. Modern pianos have entirely separate actions, and use special screws driven into holes so that the play between them can be regulated, and many older pianos use more sophisticated mechanisms.

Weights are often used to change the resistance of the keys, usually they are made of lead with a slightly conical shape and are driven into holes made in the sides of the keys. I don't know if in Europe the lead weights are exempt from the Restriction of Hazardous Substances Directive.