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Dimensions, Tolerances and Assemblies - Coggle Diagram
Dimensions, Tolerances and Assemblies
Dimensions
Parts:
Tolerance: units are also in mm, can usually be found with +/- sign, shows how much dimensions can deviate
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Extension lines: Extend from surface of object, extend slightly past dimension line and do not touch object lines (see extension line offset)
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Types of Dimensions:
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Dimensioning Circles and arc: Hole is dimensioned by the diameter and located by centrelines, arc by its radius
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Chain Dimensions: Used only if function of object would not be affected by the accumulation of tolerances
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Rules:
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Dimension lines, extension lines and object outlines should not cross and overlap
Tolerance
Importance:
Impossible to have exact measurements, rejection rates will increase and will not be realistic
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Types:
Bilateral Tolerance: allowed to vary in two directions from the specified dimension. Both directions need not vary by the same amount.
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Fits:
Clearance Fits: sufficient clearance for an object to interface with another fit, there tends to be allowance for two parts to move, such as in a door hinge.
Interference Fits: insufficient clearance for an object to interface with another fit, it would be difficult to move (or remove) the two interfacing parts. Usually, a lot of force is needed to remove the two parts
Assembly and Joints
Types:
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Revolute
Has a single rotational degree of freedom, much like a hinge.
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