Oblique Projections, ContinuedObliquedrawingpracticesIn general, begin an oblique projection by drawing a centerline (CL) skeletonand building the drawing on these centerlines. Make sure to construct allpoints of tangency, particularly when you are planning to ink in the drawing.Circles, arcs,and ellipsesObjects with surfaces parallel to the plane of projection that contain circles,arcs, and ellipses project in true size and shape. Circles not parallel to theplane. of projection project as ellipses. Circles, arcs, and ellipses have notransferable linear measurements and this requires you to inscribe the circle,arc, or ellipse in. an equilateral parallelogram or square. Draw perpendicularbisectors to the four sides of the parallelogram to locate the centers of thecircle or arc. This method works best in cavalier drawings because thereceding axis is drawn full scale. An alternate method of drawing a circle inan oblique cavalier projection is by the alternate four-center ellipse method.To draw a circle in oblique projection by the four-center method, use thistable:Step12Draw a vertical and horizontal centerline with the horizontal centerline receding from the plane of projection.Construct a circle equal in diameter to the actual circle using as acenter the intersection of the vertical and horizontal centerlines.3The constructed circle will intersect each centerline at two points.From the two points on one centerline, draw two perpendiculars tothe other centerline.45From the two points on the other centerline, draw twoperpendiculars to the first centerline.From the intersection of the four perpendiculars, draw four circulararcs.6Darken all outlines.ActionContinued on next page6-9