Key (instrument) Key (instrument) A key is a specific part of a musical instrument. The purpose and function of the part in question depends on the instrument. On instruments equipped with tuning machines, violins and guitars, for example, a key is part of a tuning machine. It is a worm gear with a key shaped end used to turn a cog, which, in turn, is attached to a post which winds the string. The key is used to make pitch adjustments to a string. With other instruments, zithers and drums, for example, a key is essentially a small wrench used to turn
Sill plate Sill plate A sill plate or sole plate in construction and architecture is the bottom horizontal member of a wall or building to which vertical members are attached. The word plate is typically omitted in America and carpenters speak simply of the "sill". Other names are ground plate, ground sill, groundsel, and midnight sill. Sill plates are usually composed of lumber but can be any material. The timber at the top of a wall is often called a top plate, pole plate, wall plate or simply "the plate". In historic buildings the sills were almost always large, solid timbers framed