Note Highlights:

Dimensioning:

Tolerances (+/-)

Imperial base unit = inch
Metric base unit = millimeter

arrow must touch extension lines

extension 3mm from object line

extension line extends 3mm from dimension line

Dimensioning Diameter:

Dimensioning Radii:
- don't need center located
- when dimensioning radii put lines to locate it if features are not straight

Dimensioning Rules:

each dimension should be clearly shown and stated

dimensioning should not be duplicated or given in 2 different ways

dimensions placed in a view where the best shape and true form are shown

avoid long extension and leader lines

place dimensions between views to improve clarity if it applies to both views

do mot assume symmetrical unless there is a centerline symbol or note

spacing between dimensions should be constant within a drawing

line up dimensions horizontally and vertically

avoid crossing dimension lines and leaders when possible

make use of notes and abbreviations and symbols