Dimension Notes

ANSI - American National Standards Institute

• organization that established standards
• not arbitrary rules
• standard way of posistioning dimensions

Why?

• describes size
• locate details on an object

Rules

• Should be for the convience of person reading the drawing
• no calculations neceessary
• no duplications
• 1st dimension line should be 3/8" from object line
• no gap between line and center line
• leader scale should equal your dimension

Leaders

• arrow to edge
• dot to surface
• 1/4" tail
• cross as few lines as possible
• any angle except horizontal or verticle
• do not pass them through corners
• short as possible

Linear Dimensions

• ALWAYS HAVE HEIGHT, WIDTH, AND DEPTH
• dont't dimension from a hidden line if possible
• locate from a common corner
• smallest dimension closet to part

Angle Dimensions

• use degree symbol (%%D)
• drawn at same angle as object being dimensioned

Circle Dimensions

• ARC always dimensioned with radius
• CIRCLE always dimensioned with diameter (%%C)
• cylinder gets dimensioned in the side view
• hole gets dimensioned where it shows

Ordinate Dimensions

• use distances on the x and y coordinates
• relative from the origin (0,0)
• UCS - user coordinate system
• move UCS
• Type "UCS"
• Type "M"
• Click where you want the origin

Counterbore & Countersink

• Underline
• Type "%%U"
• Plus/Minus Sign
• Type "%%P"
• Counterbore
• bolt head or scre flush with surface
• Countersink
• bolt or screw flush with surface