Pins 0.096 inch in diameter (from the Instrument Workshop) are tapped into holes in the balance rail and rear rail of the keyframe. The pins allow the keys to move up and down without sideways play. The holes for the pins are drilled using a 3/32 inch bit, which is slightly smaller than the pin itself to give a tight fit. I used a hand drill with a small block of oak pre-drilled to serve as a guide. To drill the holes, the keyboard is fixed to the keyframe using a few brads. The plan drawing shows where the holes are placed on the balance rail and the keyboard and keyframe are aligned before being temporarily attached. The picture below shows the holes for the balance rail after being drilled. Below the keyboard can be seen the balance rail, its bevel, and the alignment lines.
Another series of holes are drilled through the keyboard and into the back rail in a similar manner. The following picture shows the scraps of wood placed under the keyboard to provide more stiffness when the holes are drilled.
Next step is to remove the keyboard, insert the pins into the keyframe, install some paper spacers around the balance pins and some felt on the back rail to silence the keys when the fall.
The next two figures show the block of oak 7/8 in. thick used as a guide to hammer in the balance rail pins and the complete key frame.
