Various types of drafting machine may be attached to the board surface to assist the draftsperson or artist. Parallel rules often span the entire width of the board and are so named because they remain parallel to the top edge of the board as they are moved up and down. Drafting machines use pre-calibrated scales and built in protractors to allow accurate drawing measurement.
Various types of drafting machin.e may be attached to the board surface to assist the draftsperson or artist. Parallel rules often span the entire width of the board and are so named because they remain parallel to the top edge of the board as they are moved up and down Drafting machines use pre-calibrated scales and built in protractors to allow accurate drawing measurement.