Sprocket

Descriptive Geometry Notes

Manipulating(rotate) picture planes(surfaces) in order to identify:

• TSize
• TShape
• TLength
• Tangle
• Intersection
• Distances

True length lines

• If a line is parrallel to a fold line in one view, it is true length in the next

Point View

• First find TL o fline
• Create fold line perpindicular to the TL line

PO- point
PDMODE=96
PDsize=.1

TSS

• First find TL of one line
• Create a fold line perpindicular to the TL line to get the edge view(EV) of the surface
• Create a foldline parallel to edge view

Addaline

• Draw a line parrallel to F1 from 1 point to the line you want TL of
• Project the point where it hits the line you want TL of to the next view on the same line
• Connect that point to the point you started with wich gives you a TL line
• create FL perpindicular to TL which will give you your EV including a point
• Create FL parrallel to EV which will give you your TSS surface

Dimension Notes

• ANSI standards
• no arbitrary
• standard way of positioning dimensions, why?
• describe size
• locate details

Basic Rules

• For convienence for manufactor
• No calculations necessary
• no duplications

Dim line

• 1st 3/8 of an in. (9mm) from the object line should be
• lines and symbols inside extension lines if possible

Extension lines

• Extend from object but 1/16 inch (2mm) gap between object and extension line

Leaders

• Scale=Dim. scale
• runon angle so obvious not part of drawing
• 1/4 inch tail
• arrow if to edge, dot if to surface
• crosss few lines
• any<except horizontal or vertical
• don't pass through corners

Linear

• First big 3 H,W,D
• in between viewws if possible
• off view where detail is best described
• do not dim from a hidden line
• locate from common corner
• smallest dim closest to object
• no calc.
• no duplications

Angle dim

• Draw at same angle as object being dim
• use degree symbol %%D

Circular

• ARC-anything less then full circle dimas radius
• circle always diam %%C

Circular objects

• Cylinder-in profile (side) view
• hole-where it shows as a hole

Tolerances

• Hold precise tolerances for interchange ability
• how much a dim can vary

Terms

• Basic size- exact size
• Tolerance- amount  a dim can vary from basic size
• feature-identify geometry
• limits of size- max or min from exact size
• allowance-limits where smallest clearance of largest interference occurs measured at mmc

Maximum Material condition

• limit of a dim where the max material is left on the part

Least material Condition

• limit of dim where least amount of maaterial is left on part
• Types of fit
• Clearance-space between parts
• Interference- force fit
• Transition-diff combos, diff fits

Auxiliary Views

• Sometimes you needd more then 3 views
• seconday view used to show true size and shape (TSS)
• perpindicular to recommended surface
• TSS when its edge is parallel to the fold line
• SKIP A VIEW MEASURE BACK