MRSPTU

ENGINEERING GRAPHICS AND DESIGN

UNIT 5

Projection of Planes

Question banks

1. Rectangle 30mm and 50mm sides is resting on HP on one small side which is 300 inclined to VP, while the surface of the plane makes 45 degree inclination with HP. Draw it’s projections.

Solution steps:

1Surface inclined to which plane? ------- HP

1. Assumption for initial position? ------// to HP
2. So which view will show True shape? --- TV
3. Which side will be vertical? ---One small side.

Hence begin with TV, draw rectangle below X-Y drawing one small side vertical.

2.     A 30 degree to 60 degree set square of longest side 100 mm long, is in VP and 30 inclined to HP while it’s surface is 450 inclined to VP. Draw it’s projections

Solution steps:

1. Surface inclined to which plane? ------- VP
2. Assumption for initial position? ------// to VP
3. So which view will show True shape? --- FV
4. Which side will be vertical? ------longest side

3.     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.

Solution steps:

1. Surface inclined to which plane? ------- HP
2. Assumption for initial position? ------ // to HP
3. So which view will show True shape? --- TV
4. Which side will be vertical? -------- any side.

Hence begin with TV, draw pentagon below X-Y line, taking one side vertical.

4.     A regular pentagon of 30 mm sides is resting on HP on one of it’s sides while it’s opposite vertex (corner) is 30 mm above HP. Draw projections when side in HP is 30 inclined to VP.

Solution steps:

1. Surface inclined to which plane? ------- HP
2. Assumption for initial position? ------ // to HP
3. So which view will show True shape? --- TV
4. Which side will be vertical? --------any side.

Hence begin with TV, draw pentagon below X-Y line, taking one side vertical.

5.     A circle of 50 mm diameter is resting on Hp on end A of it’s diameter AC which is 30 inclined to Hp while it’s TV is 45 inclined to VP. Draw it’s projections.

Solution steps:

1. Surface inclined to which plane? ------- HP
2. Assumption for initial position? ------ // to HP
3. So which view will show True shape? --- TV
4. Which diameter horizontal? ---------- AC

Hence begin with TV,  draw rhombus below X-Y line, taking longer diagonal // to X-Y

6.     An isosceles triangle of 40 mm long base side, 60 mm long altitude Is freely suspended from one corner of Base side. It’s plane is 45 inclined to VP. Draw it’s projections.

Solution steps:

1. In this case the plane of the figure always remains perpendicular to Hp.
2. It may remain parallel or inclined to Vp.
3. Hence TV in this case will be always a LINE view
4. Assuming surface // to Vp, draw true shape in suspended position as FV. (Here keep line joining point of contact & centroid of fig. Vertical )
5. Always begin with FV as a True Shape but in a suspended position. AS shown in 1st FV.

7.     A semicircle of 100 mm diameter is suspended from a point on its straight edge 30 mm from the midpoint of that edge so that the surface makes an angle of 45 with VP. Draw its projections.

Solution steps:

1. In this case the plane of the figure always remains perpendicular to Hp.
2. It may remain parallel or inclined to Vp.
3. Hence TV in this case will be always a LINE view
4. Assuming surface // to Vp, draw true shape in suspended position as FV. (Here keep line joining point of contact & centroid of fig. Vertical )
5. Always begin with FV as a True Shape but in a suspended position. AS shown in 1st FV.

8.     Fv & Tv both are circles of 50 mm diameter. Determine true shape of an elliptical plate.

9.     Draw a regular pentagon of 30 mm sides with one side 30 inclined to xy. This figure is Tv of some plane whose Fv is A line 45 inclined to xy. Determine it’s true shape.

10. A hexagonal lamina has its one side in HP and Its apposite parallel side is 25mm above Hp and In Vp. Draw it’s projections. Take side of hexagon 30 mm long.