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Rules of dimensioning, tolerance, Assembly modelling, Clearance fit &…
Rules of dimensioning
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Dimensions should not be duplicated, i.e. same dimension should not be repeated on different views, or the same information need not be given in two different ways
Dimension lines, extension lines and object outlines should not cross or overlap
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tolerance
Tolerances are included with dimensions in engineering drawings to take into account these manufacturing limitations.
If tolerance is not given, exact measurement of the parts must be made. Rejection rate will be very high and is not realistic.
The range of tolerance will translate into the manufacturing method needed, since different manufacturing method has different degree of tolerance.
Same parts can be made from different companies and they have to be interchangeable. Tolerance ensures good quality control for parts from different companies.
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Types of tolerance
1.Bilateral Tolerance: allowed to vary in two directions from the specified dimension. Both directions need not vary by the same amount.
2.Unilateral Tolerance: allowed to vary in only one direction
3.Limit Tolerance: the upper and lower limits of the dimension are specified
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Assembly modelling
Constructing an assembly normally begins with bringing in a base component, selected because of its central role. Each component brought in needs to be oriented and located relative to other components in the assembly. Assembly joints are used between elements of components
Tpes of joints in fusion 360
- rigid
- revolute
- slider
- cylindrical
- pin slot
- planar
- ball
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Revolute Joint: Has a single rotational degree of freedom, much like a hinge.
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