Rotring T-Square Plastic Ruler, 120 cm

Rotring T-Square Plastic Ruler, 120 cm.

A T-square is the reference edge a hand-drawn technical drawing is built on: the head sits against the side of the board and the blade gives you a horizontal that is the same horizontal every time you slide it up or down.

Everything else follows from it — set squares ride on the blade to give you verticals and angles, so the accuracy of the whole sheet depends on this one tool sitting true. Keep the edge clean and never cut against it; a nicked blade transfers that nick to every line you draw afterwards.

• Fixed head — one true horizontal across the whole board
• Set squares ride on the blade for verticals and angles
• Never cut against the edge — a nick repeats on every line