Building the Key Frame

The keyframe supports the individual keys, or key levers, and guides their motion.  The middle rail, made of oak, holds the balance pins that act as the pivot point for the keys to move up and down.  The middle rail's front edge is beveled to keep from interfering with the keys when they move downward.  Small discs of felt centered on the pins under the keys cushion their contact with the rail.  The back rail, made of poplar, holds another set of pins that prevent the keys from moving horizontally.  A strip of felt along the length of the back rail cushions the keys when they fall after being struck.

The following picture shows the middle and back rails (running horizontally) before installing the pins and the felt cushions.  The strips at the sides, called stiles, support the rails at their correct elevations.  The stiles are made of poplar also.

Shown below is a closer view of the middle rail's bevel.  I used a low angle jack plane to form the bevel.  The bevel has a depth of 1/8th inch at the front and extends towards the back of the rail for approximately 7/8th inch.

The keyframe's width is a fraction of an inch wider than the keyplank.  Shown below is the uncut keyplank resting on the keyframe.  Up until now the construction has used only hand tools (frame saw, chisels, and planes).  However, when cutting out the keys I need to use a band saw.

Several lines are drawn in pencil on the keyplank to outline the keys and locate the position of the balance pins and guide pins.  The next picture shows a closer view of a one-octave span on the keyplank.