The Collaborative International Dictionary of English v.0.48:

Scaleboard \Scale"board`\ (?; commonly ?), n. [3d scale +
   board.]
   1. (Print.) A thin slip of wood used to justify a page.
      [Obs.] --Crabb.
      [1913 Webster]

   2. A thin veneer of leaf of wood used for covering the
      surface of articles of furniture, and the like.
      [1913 Webster]

   Scaleboard plane, a plane for cutting from a board a wide
      shaving forming a scaleboard.
      [1913 Webster]