# Problem 4.8 Projection of Straight Lines

Problem 4.8 Projection of Straight Lines – A line PQ 80 mm long is parallel to V.P. and inclined to H.P. by 55°. The end point P is 20 mm below H.P. and 30 mm behind V.P. Draw the projections of the line PQ.

## Procedure:

Step-1 Draw a horizontal line, which is x-y line of some suitable length.

Step-2 Draw a horizontal line of the length 80 mm at the distance 30 mm above the x-y line, and give the notations as p and q2 at the ends of the line.

Step-3 From the points p & q2 draw two projectors in down ward direction up to the distance equal to 20 mm below x-y. And mark the points as p’ – q1’, as shown in the figure. Then draw a straight line between the point p’ – q1’.

Step-4 From the point p’, draw a line of length 80 mm and at an angle 55°from the line p’ – q1’. And give the notation at the other end as q’. This is elevation of the line PQ. And its inclination with the x-y line is represented by the letter α.

Step-5 From the point q’, draw a vertical projector up to the line p-q2 and mark the notation as q. This is plan of the line PQ. And its inclination with the x-y line is represented by the letter β.

Step-6 Give the dimensions by any one method of dimensions and give the notations as shown into the figure. And make a list of the True Length & Angles made by the line PQ as shown into the figure.

## Author: Vasim Machhar

An Engineering Drawing Geek. Working at Noble Group of Institutions, Junagadh as Head of Mechanical Engineering Department.