Dimensions, tolerance and assemblies
Dimensions
Parallel Dimensioning/ Datum
Superimposed Running dimensioning
many dimension on the same surface of an object
reduce the amount of space used on a drawing. The origin point of the dimension is indicated by a small circle at intersection of the first dimension and projection line
Chain dimensioning
Each dimension is placed adjacent to the next dimension without there being a gap between each dimensioning
combined dimensioning
Uses both the chain and parallel dimensioning
Dimensioning small features
place arrow head outside of the extension line
dimensions not being able to see clearly
due to
Dimensioning of multiple features
use the same number of features( Circles) of the same dimension multiply by its dimension
dimensioning of radius
dimensioning radius with or without a center location
dimensioning of circle, arcs and holes
circle
Diameter
dimension by
arcs
Radius
dimension by
holes
located by
center line
dimensioning angles
marked with a curved dimension line and have a degree symbol
dimension should not be repeated
Tolerance
Bilateral Tolerance
the dimension can be both positive and negative
Unilateral Tolerance
dimension can only be in positive or negative
Limit Tolerance
the dimension is specific
upper limit - lower limit
Assemblies
clearance fit
interference fit
when the maximum allowed shaft size is smaller then the minimum allowed hole size
the external dimension of a part slightly exceeds the internal dimension of the part in which it is being fitted in
multiple parts are join together to make a larger product