1. Alphabet of lines
SKETCHING 101

2. ALPHABET OF LINES

3. VISABLE (OBJECT) LINES
THICK, SOLID LINES
SHOWS THE OUTLINE OF THE OBJECT VISIBLE TO THE EYE

4. HIDDEN (INVISIBLE) LINES
SHORT, EVENLY SPACED DASHES
REPRESENT SURFACES THAT ARE NOT DIRECTLY VISIBLE TO THE EYE.
ALWAYS STARTS WITH A DASH IN CONTACT WITH A LINE AT ITS START EXCEPT WHEN THE DASH WOULD FORM A CONTINUATION OF A SOLID LINE.

6. CENTER LINES ALTERNATING SHORT AND LONG LINES, LINES ARE THIN AND DARK
A LINE THROUGH THE CENTER OF AN OBJECT – ESPECIALLY ONE FOLLOWING AN AXIS OF SYMMETRY (CIRCLE, HOLE, ARC OR CYLINDER)

7. DIMENSION AND EXTENSION lINES
DIMENSION LINES – SHORT SOLID LINES WITH ARROW HEADS AT EACH END,
BROKEN IN THE MIDDLE TO SHOW DIMENSION OR VALUE
SHOWS THE DISTANCE BETWEEN 2 POINTS
EXTENSIONS LINES – SHORT SOLID LINES USED TO SHOW THE LIMITS OF DIMENSIONS.
PLACED INSIDE OR OUTSIDE THE OUTLINE OF AN OBJECT
THEY EXTEND FROM AN OUTLINE OR SURFACE, BUT DO NOT TOUCH IT.
SAME WEIGHT AS INVISIBLE LINES

8. CUTTING PLANE LINES A THICK DASHED LINE FOLLOWED BY TWO SHORTER DASHES
TERMINATES WITH A SHORT 90 DEGREE ARROWHEADS
SHOWS WERE A PART IS MENTALLY CUT IN HALF TO BETTER SEE THE INTERIOR DETAIL

9. SECTION LINES (CROSSHATCH)
THIN EVENLY SPACED LINES, USUALLY DRAWN AT A 45 DEGREE ANGLE.
INDICATES THE MATERIAL THAT HAS BEEN CUT THROUGH IN A SECTIONAL VIEW
USUALLY INDICATED WITH A LETTER TO IDENTIFY THE CUT SURFACE.

10. BREAK LINES CAN BE LONG OR SHORT
USED TO INDICATE THE PART IS BROKEN OUT TO CLEARLY SHOW A PART UNDERNEATH
ALSO USED TO REDUCE SIZE OF A DRAWING OF A LONG PART W/ UNIFORM CROSS SECTION
SHORT BREAKS INDICATED BY THICK SOLID HAND DRAWN LINES
LONG BREAKS INDICATED BY THIN SOLID RULED LINES BY FREEHAND ZIGZAGS
BREAKS ON SHAFTS, RODS, TUBES, AND PIPES ARE CURVED

11. PHANTOM LINES THIN LINES
INDICATE ALTERNATE POSITIONS OF PARTS OF THE OBJECT
SHOWS REPEATED DETAILS OR LOCATIONS OF ABSENT PARTS
ONE LONG AND TWO EVENLY SPACED SHORT DASHES (LONG DASH ON EACH END)