Crossword Puzzle Technical Drawing: InstrumentsOnline version The various types of TD Instruments: Set Squares, Tee Square, Ruler, Compass, Protractor, Divider, Pencils, Ruler by Frank Holder 1 for drawing circles of various sizes 2 to protect the drawing when removing unwanted lines 3 for drawing elliptic curves 4 to keep the drawing sheet in a fixed position 5 6 to transfer elliptic curves from one part to another 7 has measurements in degrees 8 9 10 for drawing arcs and circle 11 12 transferring measurements from ruler to work 13 to remove unwanted lines and pencil marks 14 use for measuring lengths in MM, CM and Inches 11 12 4 13 6 10 1 3 14 9