Travelling straight edge for drawing board - maintains alignment with resistance to movement reduced by mounting each end on two wheels

摘要

The movable rule (1) with a set alignment is incorporated in a draughting machine, each of its ends being mounted on two wheels (6). The arrangement reduces the effort required by the draughtsman to move the rule over the drawing board (14). The offset of the rule above the table can be adjusted by manipulating two milled wheels (9), a square with an horizontal and a vertical graduated scale being provided. One handed manipulation of both the square and rule may be contrived by providing the square with a handle and the leg of the square may have a vertical scale on each edge with the line of the top edge of the arm forming both datum points.