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COMPUTER AIDED ENGINEERING DRAWING

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Why Engineering Drawings? • Engineering drawing is a formal and precise way of communicating information about the shape, size, features and precision of physical objects. • Drawing is the universal language of engineering.

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Line ConventionsVisible Lines – solid thick lines that represent visible edges or contours Hidden Lines – short evenly spaced dashes that depict hidden features Section Lines – solid thin lines that indicate cut surfaces Center Lines – alternating long and short dashes Dimensioning Dimension Lines - solid thin lines showing dimension extent/direction Extension Lines - solid thin lines showing point or line to which dimension applies Leaders – direct notes, dimensions, symbols, part numbers, etc. to features on drawing Cutting-Plane and Viewing-Plane Lines – indicate location of cutting planes for sectional views and the viewing position for removed partial views Break Lines – indicate only portion of object is drawn. May be random “squiggled” line or thin dashes joined by zigzags. Phantom Lines – long thin dashes separated by pairs of short dashes indicate alternate positions of moving parts, adjacent position of related parts and repeated detail Chain Line – Lines or surfaces with special requirements

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Source: http://www.genium.com/pdf/dmpc.pdf123456789 1014131211Viewing-plane lineExtension lineDimension LineCenter LineHidden LineBreak LineCutting-plane LineVisible LineCenter Line (of motion)LeaderVIEW B-BSECTION A-ASection LinePhantom Line

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SketchingDrawings made without mechanical drawing tools Free-Hand

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Projection of points In 1st quadrant In 2nd quadrant In 3rd quadrant In 4th quadrant

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Quadrants

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Projection of points In 1st quadrant Above HP In front of VPA point is 30 mm in front of VP, 40 mm above HP and 25 mm in front of left profile plane. Draw its projections.

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Projection of PointsIn 1st quadrant In 2nd quadrant In 3rd quadrant In 4th quadrant

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Projection of point – I quadrant

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Projection of point – I quadrant

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Projection of points In 1st quadrant Above HP In front of VPA point is 30 mm in front of VP, 25 mm above HP. Draw its projections.

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Projection of points In 1st quadrant2. Draw the projection of a point P that is 30 mm in front of VP, 50 mm above HP and 35 mm in front of right profile plane

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Solution

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Projection of point – II quadrant

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Projection of point – II quadrant

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Projection of point – II quadrantDraw the projection of a point A lying 60mm above HP and 40mm behind VP

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Projection of point – II quadrantA point is 20 mm above HP, 45 mm behind VP and 25 mm in front of RPP. Draw its projections.

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Solution

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Projection of point – III quadrant

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Projection of point – III quadrant

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Projection of point – III quadrantA point P is 30 mm below HP, 20 mm behind VP and 25 mm behind RPP. Draw the projections of the point.

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Projection of point – III quadrantProblem 2. Draw the projection of a point P that is lying in HP, 20 mm behind VP and 30 mm behind RPP

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Solution