Presentation on theme: "Isometric ellipses In an isometric drawing, the object is viewed at an angle, which makes circles appear as ellipses. Holes Cylinders Example object –"— Presentation transcript:
1Isometric ellipsesIn an isometric drawing, the object is viewed at an angle, which makes circles appear as ellipses.HolesCylindersExample object – focus on eye piece. Inside (hole) and outside (cylinder) both appear elliptical in this sketch.
2Sketching a CircleDraw a square whose sides are the diameter of the circle.At the center of each side define the point of tangency for the circle.Draw the diagonals of the square.Orient the paper so you can draw equal arcs to construct the circle
3Introduction to Isometric Projection CUBEIsometric Projection:One type of axonometric pictorial (3-D) projection‘Iso-’ means ‘equal‘metric projection’ means ‘a projection to a scaled measure’The three dimensions are not only shown in one view, but also the dimensions can be scaled from this drawingSTART WITH A CUBEAll of the normal drawing planes (top, front, side) are equally foreshortened or tilted, and all of the major axes (X, Y, Z) are at equal rotations from each other (120 degrees apart), as in the illustration above.And, because all of the major planes are equally foreshortened, all of the measurements in these planes are equal as well as shown above. This means that the same measuring scale may be used in drawing both the width, height, and depth of objects.Isometric means equal measureAll planes are equally or proportionately shortened andtiltedAll the major axes (X, Y, Z) are 120 degrees apart
4Making an Isometric Sketch Defining Axis30o60oIsometric AxisDerive the axes from a vertex of the cube
5Ellipses Can be in Any of Three Planes Ellipse could appear in any one of the three planes (front, profile or side, horizontal or top)Major axis (long axis) of the ellipse will be along the long diagonal of the rectangleMinor axis (short axis) along the shorter diagonal.Note ellipse must have the correct orientation in the box. (Almost fills the box, if rotated 90 degrees, it would be incorrect for the plane of view.)
6Sketching an Isometric of a Hollow Pipe Isometric object without construction linesNote: Student product will have construction lines.
7Step 1 – Creating the Base Box LengthDiameterRecall that the proper way to start an isometric sketch is to lightly sketch in the box within which the object will fit.Process will fairly closely follow that described in of Bertoline.
8Step 2 – Ellipse on Front Face - Corner to corner to get centerLines to Tangent Points- Lines to tangent pointsTangent PointsNote for students that just front part of box will be shown to keep it simple in the visuals.Sketch in lines corner to corner (along major and minor axis of ellipse) to get center pointSketch perpendicular lines through center point to get tangent points on outside box.
9Step 3 – Ellipse on Front Face Sketch in ArcsTangent PointsSketch in smooth arcs to join the Tangent points on Major axis and minor axis. Radius of arc on the longer diagonal is shorter than the radius of arc on the shorter diagonal.
10Step 3 – Ellipse on Back Face and Profile Repeat for ellipse on rear faceDraw Tangent Lines for ProfileComplete Visible Part of Back EllipseNote that in case on the rear side of the pipe, only a part of the ellipse is visible. So only the part which is visible is drawn with dark lines
11Step 4 – Ellipse for Hole on Front Face Create Box for HoleSketch EllipseEncourage student to leave in their light construction lines. Constructions lines not shown here to just add focus to what is being added at this step. Note that the construction line should be much lighter and thinner than the main object lines.
12Isometric of Hollow Pipe Isometric object without construction linesNote: Student product will have construction lines.
13Summary Technical drawings are an effective communication media Projections of various types can be usedIsometric projections and creating isometric sketches has been introducedAssignments will emphasize simple isometric sketchesSummarize the objectives of the sessionWill introduce more advanced isometrics and orthographics drawing in next class
14Review Questions_______ sketches present the object in a single view, with all three dimensions represented_______ sketches present the object in a series of projections, each one showing only two of the objects’ three dimensionsWhich among the following is NOT an isometric axes (Hint: Use the Isometric Grid paper for reference)?Note on all REVIEW QUESTIONS slides:Have the students do individually and check with their partner. Will not be graded. This is for better understanding and making the students read the text book. Students could expect such questions in their mid-term and final. Answers will also be posted on WebCT.Answers:Pictorial (Axonometric/Isometric, Perspective, Oblique)Multiview/orthographicc) => spacing between any two axes can be 30, 60, 120, 240 onlya)b)d)c)120°60°240°90°
15Tips for Drawing Assignments Follow Sketching and Text conventions.Title Information is required. Avoid labels on the sketch.Leave the construction lines – MUCH lighter and thinner than the finished linesInclude centerlines on isometrics
16Tips for Drawing Assignments Do not try to shade drawing – this is not a pencil sketching class.Use grid paper. Try to sketch along grid lines. Practice sketching straight lines and curves on a grid sheet.
17Tips for Pictorial Views In pictorial views, hidden lines are not shown unless absolutely required for clarity, such as;Non-visible bottom of a blind holeImportant feature of object not in direct viewIn pictorial views, holes or notches without bottom/end visible should be assumed to go completely through the object.Centerlines are to be shown on all isometric pictorials.
18In Class AssignmentUse Isometric Sketch Paper (ISP)