The balance pins and key frame support the key levers, which move like a playground teeter-totter or see-saw. Without being weighted, the keys tend to be front heavy. So the back of the keys require extra weight to ensure that they fall back down after being pressed. How much weight is needed to ensure they fall back down just right? After some research, I found that about 2.5 grams placed on the front of the key where a finger would normally press down during playing was good enough. Lead is added to the back of the keys to counter-balance the 2.5 gram weight on the front. A penny minted in the U.S. after 1985, which weighs exactly 2.5 grams, was placed on the front of the key. Lead cut from 1/4-inch diameter wire was shifted in position on the back of the key lever until the key was balanced. The lead poses a potential health risk, so gloves are a good choice for personal protection.
After marking the position of the weights in their correct position, 1/4-inch holes were drilled into the key levers. The typical width of the key lever is about 1/2-inch. The holes were drilled to a depth of 3/8-inch using a drill press with a 1/4-inch brad point drill bit.
The lead often comes as a coil. When being cut to length, the lead has a tendency to deform. The deformity can cause the weight to resist being inserted into the hole. If there is too much resistance, the lead has a tendency to mushroom out at the top when being tapped down with a hammer. (The lead also has a tendency to oxidize quickly; so I keep the lead in a sealed plastic bag).
After 51 balancing acts, the keys are now properly weighted, I hope!
