Tuesday, April 12, 2011
Monday, April 11, 2011
Descriptive Geometry
Manipulating (rotating) picture planes (surfaces) in order to identify
True Length Lines
- True size
- True shape
- True length
- True angle
- Intersection points
- Distances
True Length Lines
- If a line is parallel toa fold line in 1 view, it is true length in the next view
- You must first find a true length line
- Create a fold line perpindicular to the true length (TL) line
- You must find TL of one line
- Create fold line perpendicular to the TL line to get the edge view (EV) of the surface
- Create fold line parallel to the edge view
- Addaline allows you to skip a view when finding TL
Monday, February 28, 2011
Auxiliary Views
Auxiliary Views
- Sometimes you need more than three views to tell the whole story
- Secondary view shows true size and shape(TSS) of a surface that shows foreshortened in a;; traditional views
- A surface is TSS when its edge in the next view is parallel to the fold line
Tolerances
Tolerances
Clearance Fit
- Hold precise tolerances to insure the interchangeability of parts
- Process of determining the amount a dimension can vary from its theoretical size
- Exact theoretical size
- Amount dimension can vary from basic size
- Feature used to identify the geometry of a drawing being referenced
- Maximum and minumum allowable size
- Limits where smallest clearance or largest interference occur
- Limits dimensioning
- Plus/ minus dimensioning(deviation)
- Symmetrical Dimensioning
- Max Material Condition-limit of a dimension where the maximum material is left on the part
- Least Material Condition-limit of a dimension where the least amount of material is left on a part
Clearance Fit
- All Dimension combinations will produce clearance between parts(running and sliding fit)
- All combinations of dimensions will produce a force fit
- Different combination of dimensions will produce different kinds of fits
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