Parallel straightedges maintain parallel motion throughout their length. A
system of cords and internal pulleys kept at moderate tension support the
straightedge at both ends and allow travel up and down the tabletop. The
cord used in a parallel straightedge may be fiber or coated wire.
Straightedges are made in plastic, wood, or metal.
The major advantages of a parallel straightedge are as follows:
it is used by both left- and right-handed DMs,
it is easily restrung,
it is ideal when space is tight, and
it is simple to adjust and care for.
Keep the parallel straightedge clean, particularly underneath where it contacts
with the paper surface. Periodically check the tension of the cord and adjust
it as necessary. When the cord becomes frayed or kinked, restring the
internal pulleys. Never cut against the edge of a straightedge.
Figure 2-14 shows a parallel straightedge with a tension adjuster.
Figure 2-14. A parallel straightedge.
Continued on next page