1. DIMENSION PLACEMENT
By:
Muhammad Zahid

2. DIMENSION
The size and other details of the object essential for its construction and function, using lines, numerals, symbols, notes, etc are required to be indicated in a drawing by proper dimensioning.
The dimensions are written either above the dimension lines or inserted at the middle by breaking the dimension lines.

3. DIMENSION PLACEMENT There are two system of dimension placement.
Aligned system.
Unidirectional system
In aligned system dimension are placed perpendicular to the dimension lines in such a way that it may be read from bottom edge or right hand edge of the drawing sheet.

4. DIMENSION PLACEMENT
Aligned system.

5. DIMENSION PLACEMENT UNIDIRECTIONAL SYSTEM
The dimension are placed such that it can be read from the bottom edge of the drawing sheet.
The dimension lines are broken near the middle for inserting the dimensions.
This system is used on large drawings like aircrafts, automobiles etc.

6. DIMENSION PLACEMENT
Unidirectional system:-

7. DIMENSION PLACEMENT UNIT OF DIMENSION:-
The dimension should be in millimeters, omitting the abbreviation mm.
If the dimensions are not possible in millimeter and another unit is used, even then only dimension figures are written.
A foot note showing the dimension scale like “all dimensions in centimeters” should be placed at prominent place near title block.

8. DIMENSION PLACEMENT Rules to be followed for dimensioning.
Each feature is dimensioned and positioned only once.
Each feature is dimensioned and positioned where its shape shows.
The same unit of length should be used for all the dimensions on a drawing. The unit should not be written after each dimension, but a note mentioning the unit should be placed below the drawing.
Dimension lines should not cross each other. Dimension lines should also not cross any other lines of the object.

9. DIMENSION PLACEMENT Dimension should be given outside the view.
Dimension should be given inside only when they are more clear and easily readable.
Every solid has three dimensions, each of the geometric shapes making up the object must have its height, width, and depth indicated in the dimensioning.
Aligned system of dimensioning is recommended.

10. DIMENSION PLACEMENT
Should be placed at least 10 mm away from the outline.
All other parallel dimensions should be at least 6 mm apart, or more, if space permits.

11. DIMENSION PLACEMENT
Specification of dimension lines

12. DIMENSION PLACEMENT
Dimensioning of angles:- Normal convention for dimensioning of angles

13. FEW EXAMPLES DURING DIMENSIONING OF SOLIDS
PRISM:- This is the most common shape and requires three dimensions. Two dimensions shown on the principal view and the third dimension on the other view

14. FEW EXAMPLES DURING DIMENSIONING OF SOLIDS
CYLINDER:-
Cylinder is the second most common shape. It requires  two dimensions: diameter and length, both shown preferably on the rectangular view.
dimension of cylinder should not be given as radius.

15. FEW EXAMPLES DURING DIMENSIONING OF SOLIDS
RIGHT PYRAMIDS:- requires three dimensions – dimensions of the base, width and altitude.

16. FEW EXAMPLES DURING DIMENSIONING OF SOLIDS
SPHERES:- It requires only one dimension. i.e. diameter. However in case of extra features, those dimensions are required to be provided.

17. GEOMETRIC CONSTRUCTION
By:
Muhammad Zahid

19. GEOMETRIC CONSTRUCTION
Drawing consists of construction of primitive geometric forms viz.  points, lines and planes that serve as the building blocks for more complicated geometric shapes and defining the position of object in space.

20. GEOMETRIC CONSTRUCTION
The use of lines for obtaining the drawing of planes is shown in figure

21. GEOMETRIC CONSTRUCTION
Solids are obtained by combination of planes. Plane surfaces of  simple solids are shown in figure

22. GEOMETRIC CONSTRUCTION
In addition curved surfaces also exists.

23. GEOMETRIC CONSTRUCTION
Primitive geometric forms The shapes of objects are formed from primitive geometric forms . These are
Point
Line
Plane
Solid
Doubly curved surface and object
Warped surface

24. GEOMETRIC CONSTRUCTION
POINT:-
A point is a theoretical location that has neither width, height, nor depth and  describes exact location in space.
A point is represented in technical drawing as a small cross made of dashes that are approximately 3 mm long.
A point is used to mark the locations of  centers and loci, the intersection ends, middle of entities

25. GEOMETRIC CONSTRUCTION
POINT:-

26. GEOMETRIC CONSTRUCTION
LINE:-
A line is a geometric primitive that has length and direction, but no thickness. Lines may be straight, curved or a combination of these.
Lines have few important relationship or conditions, such as parallel, intersecting, and tangent. 
Lines can be of specific length or non-specific length. A Ray is a Straight line that extends to infinity from a specified point.

27. GEOMETRIC CONSTRUCTION
LINE:-

28. GEOMETRIC CONSTRUCTION
Bisecting a line:-
A line can be bisected by taking A as centre and radius equal to higher than half the length of line AB, draw an arc. With B as centre and with the same radius draw another arc intersecting the previous arc. The line joining the intersection points is the perpendicular bisector of the line AB.

29. GEOMETRIC CONSTRUCTION
Bisecting a line:-

30. GEOMETRIC CONSTRUCTION
Dividing a line into equal parts
Draw a line MO at any convenient angle (preferably an acute angle) from point M.
From M and along MO, cut off with a divider equal divisions (say three) of any convenient length.
Draw a line joining ON.
Draw lines parallel to MO through the remaining points on line MO.
The intersection of these lines with line MN will divide the line into (three) equal parts.

31. GEOMETRIC CONSTRUCTION
Dividing a line into equal parts

32. GEOMETRIC CONSTRUCTION
Locating tangent points on circle and arcs

33. GEOMETRIC CONSTRUCTION
Drawing an arc tangent to a given point on the line
Given line AB and tangent point T. Construct a line perpendicular to line AB and through point T.
Locate the center of the arc by marking the radius on the perpendicular line.
Put the point of the compass at the center of the arc, set the compass for the radius of the arc, and draw the arc.

34. GEOMETRIC CONSTRUCTION
Drawing an arc, tangent to two lines

35. GEOMETRIC CONSTRUCTION
Drawing an arc, tangent to a  line and an arc

36. ASSIGNMET 1
Drawing following object on A4 paper. Apply title block with complete details