Not only plastic, but also wood rulers, especially the long, at carrying out with their help lines are often displaced under the pressure of the pencil or ruling pen. This does not happen, if a measuring instrument to give a small deflection, heating it over the middle of the steam jet from the spout of a boiling kettle. Now, pressing a line of hand tighter squeeze its middle, but the ends. The line will not “go” and if one of the plane covered with a layer of rubber cement. But this method is worse: to move the tool across the paper becomes more difficult.
Yu FEDCHUK