Name and explain seven types of sketch line techniques. What is the meaning of the following Abbreviations: DRG, A/F?

Here are the answers to your questions:

12) Name and explain seven types of sketch line techniques:

1. Freehand Lines: Lines drawn without the aid of a ruler or straightedge, relying on hand-eye coordination to create straight or curved lines. Used for initial rough sketches and conceptual designs.
2. Construction Lines: Very light, thin lines used as guides to lay out the basic shape and proportions of a sketch. They are usually erased or made very faint in the final drawing.
3. Outline/Object Lines: Darker, thicker lines used to represent the visible edges and contours of an object. They define the main shape of the part.
4. Hidden Lines: Dashed lines used to represent edges or features of an object that are not directly visible from the current view.
5. Center Lines: Long-short-long dashed lines used to indicate the axis of symmetry for symmetrical parts, or the center of circles and arcs.
6. Dimension Lines: Thin lines with arrowheads at each end, used to indicate the extent of a measurement. The numerical value of the dimension is placed along or above this line.
7. Extension Lines: Thin lines that extend from the object's features to the dimension line, indicating where the measurement begins and ends. They do not touch the object's outline.

13) What is the meaning of the following Abbreviations:

a) DRG: Drawing

b) A/F: Across Flats

c) A/C: Across Corners

d) I/D: Inner Diameter

e) O/D: Outer Diameter

14) What is the meaning of the following symbols:

a) $\phi$: Diameter (The student's answer "center line" is incorrect. The symbol for center line is a chain line.)

b) R: Radius

c) $\perp$: Perpendicular