polytechnic Engineering sem 2 Engineering drawing ch-1 notes + 20 MCQs

This chapter provides a detailed description of the various instruments used in engineering drawing and their operational principles. It offers an in-depth explanation regarding the proper selection and technical application of essential tools, such as drawing boards, T-squares, set squares, and compasses. The textual material not only outlines methods for accurately drawing lines and angles but also offers crucial tips on drawing sheet layout and maintaining neatness. Furthermore, it incorporates various geometric problems and objective-type questions to facilitate student practice. Ultimately, this guide emphasizes the importance of tool maintenance and precision in producing high-quality technical drawings.

(यह पाठ इंजीनियरिंग ड्राइंग में उपयोग किए जाने वाले विभिन्न उपकरणों और उनकी कार्यप्रणाली का विस्तृत विवरण प्रदान करता है। इसमें ड्राइंग बोर्ड, टी-स्क्वायर, सेट-स्क्वायर और कंपास जैसे आवश्यक साधनों के सही चयन और उनके तकनीकी उपयोग को गहराई से समझाया गया है। पाठ्य सामग्री न केवल रेखाओं और कोणों को सटीकता से खींचने की विधियाँ बताती है, बल्कि ड्राइंग शीट के लेआउट और स्वच्छता बनाए रखने के महत्वपूर्ण सुझाव भी देती है। इसके अतिरिक्त, विद्यार्थियों के अभ्यास के लिए इसमें विभिन्न ज्यामितीय समस्याओं और वस्तुनिष्ठ प्रश्नों को सम्मिलित किया गया है। अंततः, यह मार्गदर्शिका उच्च गुणवत्ता वाली तकनीकी ड्राइंग तैयार करने के लिए उपकरणों के रख-रखाव और सटीकता के महत्व पर बल देती है।)

Here are the notes and objective-type questions based on the provided text.

Notes on Drawing Instruments and Their Uses

1. Introduction to Drawing Instruments

Purpose: Drawing instruments are used to prepare accurate and easy-to-read drawings. The accuracy depends significantly on the quality of the instruments .

Essential Instruments: Include a drawing board, T-square, set-squares, an instrument box (compasses, dividers, inking pen), scales, protractor, French curves, paper, pencils, an eraser, drafting pins/tapes, sand-paper block, and duster .

2. Key Instruments and Functions

Drawing Board: Made of soft wood strips and cleated at the back by two battens to prevent warping. It features an ebony "working edge" on one side, which guides the T-square .

T-Square: Consists of a stock and a blade joined at right angles. It is used exclusively for drawing horizontal lines and acts as a base for set-squares .

Set-Squares: Transparent tools available in 30°-60° and 45° formats. They are used for drawing vertical or inclined lines . Combined with a T-square, set-squares can create angles in multiples of 15° (e.g., 15°, 75°, 105°) .

Drawing Instrument Box:

Compasses: Used for drawing circles and arcs. For large circles (over 150 mm radius), a lengthening bar is attached . For very small circles (less than 25 mm radius), a small bow compass is used .

Dividers: Used to transfer dimensions, step off equal distances, and divide lines/curves . A small bow divider is highly convenient for setting off short, equal distances .

Inking Pen: Used for drawing straight lines and non-circular arcs in ink .

Scales: Designated M1 to M8, scales are used to transfer true or relative dimensions. Importantly, a scale should never be used as a straight-edge for drawing lines .

Protractor: A semi-circular tool (0° to 180°) used to draw or measure angles that cannot be obtained using set-squares .

French Curves: Used to draw complex curves that cannot be drawn with a standard compass .

3. Drawing Materials and Accessories

Drawing Papers: Available in sizes A0 to A5. The surface area of an A0 sheet is exactly one square metre. Successive sizes are obtained by halving the length of the preceding size .

Drawing Pencils: The quality of the drawing heavily relies on the pencil grade .

Hard pencils (e.g., 3H, 4H) are used for fair work and thin lines .

Soft pencils (e.g., HB) are used for lettering, dimensioning, and freehand sketching .

Leads are typically shaped into a conical point for sketching/lettering, or a chisel edge for drawing uniform-thickness long lines .

Accessories: Erasers remove unnecessary lines , sand-paper blocks sharpen the pencil lead , and dusters clean rubber crumbs .

Drafting Machine: Combines the functions of a T-square, set-squares, scales, and protractor, offering significant ease and time savings .

20 Objective-Type Questions

1. To prevent the warping of a drawing board, what are attached to its back?

A) Packings

B) Wooden blocks

C) Battens

D) Cleats

Answer: C) Battens

2. The edge of the drawing board on which the T-square slides is called the:

A) Straight edge

B) Working edge

C) Chisel edge

D) Ebony edge

Answer: B) Working edge

3. The T-square is primarily used for drawing which type of lines?

A) Vertical

B) Inclined

C) Horizontal

D) Curved

Answer: C) Horizontal

4. The two main parts of a T-square are:

A) Vertical and horizontal edge

B) Straight edge and working edge

C) Stock and blade

D) Head and arm

Answer: C) Stock and blade

5. Angles constructed by the combined use of a T-square and set-squares are generally in multiples of:

A) 10°

B) 15°

C) 20°

D) 25°

Answer: B) 15°

6. Which instrument is attached to a compass to draw large-size circles (radius > 150 mm)?

A) Straight bar

B) Small bow compass

C) Lengthening bar

D) Divider

Answer: C) Lengthening bar

7. A small bow compass is specifically used for drawing small circles and arcs with a radius of less than:

A) 10 mm

B) 15 mm

C) 25 mm

D) 50 mm

Answer: C) 25 mm

8. Which tool is used to transfer dimensions from one part of a drawing to another?

A) Scale

B) Divider

C) Compass

D) Protractor

Answer: B) Divider

9. For drawing curves that cannot be drawn with a regular compass, which instrument is used?

A) Protractor

B) French curves

C) Set-squares

D) Bow compass

Answer: B) French curves

10. What is the designated surface area of an A0 size drawing paper?

A) 0.5 square metre

B) 1 square metre

C) 1.5 square metres

D) 2 square metres

Answer: B) 1 square metre

11. A standard scale should NEVER be used as a:

A) Straight edge for drawing lines

B) Tool for transferring dimensions

C) Reference for relative dimensions

D) Guide for the compass

Answer: A) Straight edge for drawing lines

12. Which of the following instruments combines the uses and advantages of a T-square, set-squares, scales, and a protractor?

A) Roll-n-draw

B) French curve

C) Drawing instrument box

D) Drafting machine

Answer: D) Drafting machine

13. To remove unnecessary lines without damaging the paper surface, one should use:

A) A duster

B) Chalk

C) A sand box

D) An eraser

Answer: D) An eraser

14. For drawing long, thin lines of uniform thickness, the pencil lead should ideally be sharpened into a:

A) Conical point

B) Pointed edge

C) Chisel edge

D) Flat surface

Answer: C) Chisel edge

15. Which grade of pencil is most suitable for freehand sketching and lettering?

A) 3H

B) 4H

C) HB

D) 2H

Answer: C) HB

16. The standard size of a B2 drawing board is:

A) 1000 × 1500 mm

B) 700 × 1000 mm

C) 500 × 700 mm

D) 350 × 500 mm

Answer: C) 500 × 700 mm

17. The standard semi-circular protractor is graduated to measure angles ranging from:

A) 0° to 90°

B) 0° to 180°

C) 0° to 270°

D) 0° to 360°

Answer: B) 0° to 180°

18. What tool is specifically used for setting off short equal distances and marking minute divisions?

A) Small bow divider

B) Lengthening bar

C) Scale

D) Small bow compass

Answer: A) Small bow divider

19. What is the primary purpose of a sand-paper block in engineering drawing?

A) To clean the drawing board

B) To sharpen the pencil lead

C) To smooth the edges of the drawing paper

D) To erase ink marks

Answer: B) To sharpen the pencil lead

20. The inking pen (from the drawing instrument box) is used for drawing:

A) Straight lines and non-circular arcs in ink

B) Large circular arcs in ink

C) Thick boundary borders only

D) Freehand curves in ink

Answer: A) Straight lines and non-circular arcs in ink