oblique planes

oblique planes

1. Introduction When a plane surface is inclined to one of the principal plane and a side or a diagonal or diameter of a plane surface is a parallel to that principal plane and inclined to other plane surface will be called oblique plane. Projection of oblique planes are drown in three stages: When a plane surface is inclined to H.P When a plane surface is inclined to V.P

2. When a plane surface is inclined to H.P:- When a plane surface is inclined to H.P and a side or a diagonal or a diameter is parallel to H.P and inclined to V.P projection of plane will be obtain in following stage: Initial position Intermediate position Final position

3. X Y a b c d a’ b’ c’ d’ a 1 b 1 c 1 d 1 a 1 b 1 c 1 d 1 a’ b’ d’ c’ c’ 1 d’ 1 b’ 1 a’ 1 45 30 Problem 1: Rectangle 30mm and 50mm sides is resting on HP on one small side which is 30 inclined to V.P, while the surface of the plane makes 45 inclination with HP. Draw it’s projections. Surface // to Hp Surface inclined to Hp Side Inclined to V.p

4. Problem 2: A regular pentagon of 30 mm sides is resting on HP on one of it’s sides with it’s surface 45 inclined to HP. Draw it’s projections when the side in HP makes 30 angle with VP b 1 d 1 a 1 e 1 b’ 1 e’ 1 c’ 1 d’ 1 a’ 1 X Y a’ b’ d’ c’e’ 30 b 1 c 1 d 1 a 1 e 1 a b c d e a’ b’ d’ c’e’ 45 º c 1

5. Problem 3: Draw projections of a rhombus having diagonals 125 mm and 50 mm long, the smaller diagonal of which is parallel to both the principal planes, while the other is inclined at 30 º to the H.P. X Y a b c d 125 a’ b’d’ c’ a’ b’d’ c’ 30 º a 1 b 1 c 1 d 1 a 1 b 1 c 1 d 1 a 1 ’ b 1 ’ c 1 ’ d 1 ’ 50

6. When a plane surface is inclined to V.P:- When a plane surface is inclined to v.p and side or diagonal and diameter is parallel to v.p and inclined to H.P.

7. a’ b’ c’ a.b c 50 70 a.b c a 1 ’ b 1 ’ c 1 ’ a 1 ’ b 1 ’ c 1 ’ a 1 b 1 c 1 45 º Problem 1 : A plate having shape of an isosceles triangle has base 50 mm long and altitude 70 mm. It is so placed that in the front view it is seen as an equilateral triangle of 50 mm sides and one side inclined at 45 º to xy . Draw its top view

8. Problem 2: A semicircular plate of 80mm diameter has its straight edge in the VP and inclined at 45 to HP . The surface of the plate makes an angle of 30 with the VP. Draw its projections. X Y 1’ 2’ 3’ 4’ 5’ 6’ 7’ 17 26 35 4 30 º 17 26 35 4 1 1 ’ 2 1 ’ 3 1 ’ 4 1 ’ 5 1 ’ 6 1 ’ 7 1 ’ 1 1 ’ 2 1 ’ 3 1 ’ 4 1 ’ 5 1 ’ 6 1 ’ 7 1 ’ 45 º 1 1 2 1 3 1 4 1 5 1 6 1 7 1 Ø 80

9. Problem 3: A circular plate of negligible thickness and 50 mm diameter appears as an ellipse in the front view, having its major axis 50 mm long and minor axis 30 mm long. Draw its top view when the major axis of the ellipse is horizontal. X Y 1’ 2’ 3’ 4’ 5’ 6’ 7’ 8’ 9’ 10’ 11’ 12’ 1 2, 12 3, 11 4, 10 5, 9 6, 8 7 1 2, 12 3, 11 4, 10 5, 9 6, 8 7 50 Ø 30 1 1 ’ 2 1 ’ 3 1 ’ 4 1 ’ 5 1 ’ 6 1 ’ 7 1 ’ 8 1 ’ 9 1 ’ 10 1 ’ 11 1 ’ 12 1 ’ 1 1 ’ 2 1 ’ 3 1 ’ 4 1 ’ 5 1 ’ 6 1 ’ 7 1 ’ 8 1 ’ 9 1 ’ 10 1 ’ 11 1 ’ 12 1 ’ 1 1 ’ 2 1 ’ 3 1 ’ 4 1 ’ 5 1 ’ 6 1 ’ 7 1 ’ 8 1 ’ 9 1 ’ 10 1 ’ 11 1 ’ 12 1 ’