The "rabbet" is found on quality drafting aids to enable the draftsman to "ink" a line along either the triangle, straight edge, or curve to prevent the "ink" from running under the edge being followed. Of course, the "rabbet" had to be placed down against the drafting surface. Old timers used to tape coins to the underside to raise the edge above the paper, linnen, or mylar drafting medium. Might be of use today when us old timers use felt tip pens in the wood shop !
steveo
steveo
