cbse syllabus for class 12 Engineering Graphics

CLASS XII (Theory)

One Paper                                                   3 Hours                                                  70 Marks Unit                                                                                           Mark
 I.  Isometric projections of solids                                                                                       25

II.     Machine Drawing

A.      Drawing of Machine parts                                                                                15

B.      Assembly Drawings and Dis-assembly drawings                                                   30

1.       Bearings

2.       Rod joints

3.       Tie-rodand pipe joints

4.       Couplings

5.       Pulleys

Total Marks         70

Unit I:    Isometricprojection of solids                                            50 Pds.

(i)           Construction of isometric scale showing main divisions of 10mm and smaller divisions of

1mm, also showingthe leading angles. Drawing helping view/s such as triangles, pentagon, hexagon etc using isometric scale.

(ii)          Isometric projections (drawn to isometric scale) of solids such as cube, regular prism and pyramids(triangular, square,pentagonal and hexagonal), cone, cylinder, sphere,hemi-sphere, frustumof right regular pyramids (triangular, square,pentagonal, hexagonal) and cone, when they are cut by a plane parallel to the base. The axis and the base side of the solid should be eitherperpendicular to H.P. / VP or parallel to HP and VP. (Indicatethe direction of viewing)

(iii)         Combination of two solids (except "frustum" of Pyramids and Cone) Keeping the base side parallelor perpendicular to H.P./V.P. and placed centrallytogether, axis of both the solids should not be given parallel to H.P.

Note:     (1)Question on frustum will be asked in vertical position only. (2)Hidden lines are not required in isometric projection.

Unit II:   Machine Drawing(as per SP 46 : 2003)

A.	Drawing of machine parts	36 Pds.
	(i)    Drawing to full size scale with instruments.	9 marks
	(Internal choice will be given between any two of the following).

Introduction of threads:Standard profilesof screw threads square, knuckle, B.S.W., Metric

(external and internal). Bolts (square, Hexagonal, Tee and Hook);Nuts: (square and hexagonal), Plain washer, combination of nut and bolt with or without washer for assembling two parts together, Single rivetedlap joint with standard dimensions.

(ii)    Free-hand sketches                                                                                    6 marks

(Internal choice will be given between any two of the following.

Conventional representation of external and internal threads; studs (plain, square-neck and collar),screws (round-head, cheese-head, 900 flat countersunk-head, hexagonal socket- head and grub-screw). Types of rivets:- snap head, pan head-without taperedneck, flat head and 600 countersunk flat head : Types of sunk-keys (rectangular taper, woodruff and double-head feather key with gib head on both ends).

B.           Assembly drawings and Dis-Assembly drawings                                               82 Pds. (Internal choice will be given betweenan Assembly drawing and a Dis-Assembly drawing). Note:

1.    In all Assembly drawings, half sectional front view will be asked. Side/End view or Top View/Plan will be drawn without section.

2.    In all the Dis-assembly drawings (asterix * markedonly), only two orthographic views (one of the two views may be half in sectionor full in section) of any two parts.

3.    (a)     In all sectional views,hidden lines / edges are not to be shown. (b)      In all full views, hidden/edges are to be shown.

1.           Bearings

* (i)  Open-Bearing

* (ii) Bushed-Bearing

(iii) Footstep-Bearing (only sectional front-view will be asked)

(iv) Simple Plummer-Block (only sectional front view will be asked with only round brasses).

2.           Rod-Joints

* (i)  Cotter-joints for circular-rods (socket and spigot joint)

* (ii) Cotter-joints for round-rods (sleeve and cotter joint)

* (iii) Cotter-joints for square rods (Gib and cotter-joint)

(iv) Knuckle-joints (only sectional front view will be asked)

3.           Tie-rod and Pipe-joint

* (i)  Turnbuckle

* (ii) Flange pipe joint

4.           Couplings

(i)  Unprotected FlangeCoupling (having socket and spigot arrangement)

* (ii) Protected Flange Coupling

5.	Pulleys
	(i)	Solid cast Iron Pulley (upto 200 mm diameter) having solid web
	(ii)	Single groove V-belt pulley (upto 200 mm diameter)

Practicals

One paper (Practical)                                3 Hours                                    30 Marks,  72 Pds.

(I)     To perform the following jobs from the given views of the prescribed Machine

Block (One).

Value-Points

1.    Copy the given views                                                                                               12. Drawing the missing view with hidden lines                                                                    23.      Sketching the Isometric view vithout hidden edges                                                 5

4.    To    make    the   machine    block   of   the   above    in   three    dimensions. (not to scale but approximately proportionately) drawn with any medium i.e. thermocol, soap-cake, plasticine, clay, wax, orchsis ( available with flowerists) etc. 7

(II)   "Computer aided design" CAD - Project                                                                   10

Projectfile to be submitted on the simple solids (Prism, Pyramids and frustums of equilateral triangle, square,pentagon and hexgon) or machine blocks as prescribed in part-I by using the "computer aided design" CAD software.

(III)  (i)      Sessional work relating to machine blocks as prescribed.                                          3 (ii) Viva-voice based on part-I and part-II                                                                                                2

Total Marks        30

Recommended Books:-

(i)      Engineering Graphics-Class XI-Pubished by C.B.S.E, New Delhi.

(ii)     Engineering Graphics - Class XII - Published by C.B.S.E. New Delhi.