31372 - Computer-Aided Drawing L

Course Unit Page

Academic Year 2018/2019

Learning outcomes

The course aims to provide the necessary basis for the understanding of the main features of the most modern programs of Computer aided design ( CAD ) and for the proper use of such programs as part of the Technical Design . The course consists of a first part dedicated to ensuring students learning the basic rudiments of the Technical Industrial Design . In the second part of the course discusses the issues of its computer-aided design and describes the principal methodologies used in modeling , editing , coordinate transformation and visualization of curves , surfaces and solids .

Course contents

Architecture of a CAD (Computer Aided Design). Hardware: computer, dynamic memory (RAM), mass storage (HDD), flexible disks, CD-ROM. Data input: keyboard, mouse, tablets digitalizzatrici, scanner. Output: Display Devices vector and raster-scan, hard-copy devices (plotters, dot matrix, inkjet, laser). Software: interface with the operator, defining and designing the model, image generation (rendering), database management, applications, utilities. Advantages and limitations of CAD.


Notes on raster and vector graphics with particular attention to the use in CAD systems.


The graphics primitives, the initial settings of the design, how to enter data, how to select objects, editing commands objects, the ability to display, how to support the targeting, the use of layers, the use of blocks, dimensioning of a drawing, text, headers, and squaring, raster images, the backgrounds, the use of paper space, the problems of the press, simple graphics primitives, the graphics primitives complex, the design of a relief, the blocks attributes.

Bisecting a segment of an arc, of a corner. Perpendicular to a segment (a straight line) from a given point: external, belonging to it (center or end). Parallel to a given line (at a given distance, for a given external point). Transactions related to corner. Trisection of the right angle and angle plate. Division of a segment into equal parts. Tangents to a circle from a point outside or belonging. Circle with given radius tangent to a straight line in one of its points. Bribes internal and external to the two circles. Circle through three points, fittings line and circumference with arc of given radius. Regular polygons: triangle, square, pentagon, hexagon and octagon with side assigned or circumscribed circle. Construction of a polygon with a number of side given the length side or the circumscribed circumference. Plane curves (ellipse, parabola, hyperbole, oval, ovolo, evolving in circumference).

Study and comparison of snapping and object snapping in a  CAD system.

Representation with orthogonal projection on two orthogonal planes of points, lines, planes. Conditions of membership of a point and a straight line and plane, and point plan. Terms of coplanarity, incidence and parallelism for lines; of parallelism between floors. The third plane of projection: determination of the third projection of points, lines, planes, curves. Orthogonal projection of plane figures and solids. Criteria for the identification and representation of the lines in sight and no.

General. Method of tipping. Rollovers of points, lines, segments, plane figures lying in planes perpendicular to the principal plane of projection.


Axonometric projections, orthogonal and future
Reduction factors. Axonometric oblique unified (cavalier; UNI 4819). Parallel perspective orthogonal or isometric orthogonal. Axonometric isometric unified (UNI 4819). Axonometric representation of flat surfaces, prisms, pyramids; Exact and approximate representations of circles, curves and solids of revolution. The concept homography and stereograph.

Aim of sections: ideal plane of section. Plane sections of prisms and pyramids. Sections of solids of revolution (cylinder, cone, sphere, torus). Determination of the contour lines of the sections: method of generating and auxiliary method of section planes. Solids obtained by section plane (frustum of a pyramid, cone, cylinder oblique, etc ...). Use the PATTERN for obtaining the backgrounds in the CAD system.

General. Interpenetration of prisms and pyramids. Specific use of the auxiliary section planes. Determination of the intersection line on the interpenetration of solids of revolution: method of the generatrices, the method of the auxiliary plane section, method of auxiliary spheres.

Basis, dimension lines and reference, layout and reading of the shares. Dimensioning systems (in series, in parallel, overlapping dimensions, dimensioning combined, in coordinates, polar coordinates). Particular agreements of dimensioning (solid of revolution, circles, spherical surfaces, square, chamfers and rounding elements regularly or irregularly arranged). Criteria for selection of the reference elements and general rules for proper dimensioning.
Using the controls of DIMENSION and their setting for correct dimensioning of the drawing.
Coordinate systems and reference systems
· Coordinate Systems:
· Cartesian coordinates
· Cylindrical Coordinates
· Spherical Coordinates or Polari
· Coordinates Homogeneous
· Reference systems
· Local
· Global
· Observer
· Views
Onscreen representation of graphics primitives and outline of the classical algorithms.
UNITA 'Basic geometrical
Methods of representation of the main basic geometric units.
· Offsets
· Rotations
· Transformations of scale
· Symmetry and Reflection


CHIRONE, TORNINCASA, Disegno Tecnico Industriale, ed. Il Capitello, Torino.

CONTI, Disegno tecnologico, vol. 1, 2, ed. Pitagora, Bologna.
SOBRERO, Corso di Disegno, solo vol. 1, ed. Pitagora, Bologna.
FILIPPI, Disegno di Macchine, vol. 1, 2, ed. Hoepli, Milano.
Mortenson, Modelli geometrici in computer graphics, McGraw-Hill.

Teaching methods

The course consists of a theoretical part, given in unified turns in frontal mode in the classroom. At the link:

it is possible to download the course slides and the exercises developed in the exercises.

The exercises take place in two separate shifts: first round for students with initials of the surname A-K and second round with students with initials of the surname L-Z. The two shifts have the same contents.
Up to the maximum capacity of the laboratory (120 workstations) it is also possible to attend both shifts and / or refrequent. If the capacity is exhausted, priority must be given to the holders of the first frequency year shift.

In the laboratory, guided exercises will be performed by hand and / or computer. Each student will have a configured station at his disposal and must develop the exercises himself.
The teacher performs most of the exercises at the projector.
Students must carry out the exercises performed in the laboratory and, possibly, exercises indicated as to be performed autonomously or voluntarily. It is possible to have an educational software license for installation on your notebook: the indications will be given at the beginning of the course for the best update of the information. The use of the notebook in the laboratory is not recommended.

The student must save the exercises performed on their own USB memory drive from time to time.

Assessment methods

The exam consists of:

1) a multiple-choice test on the computer ("Part 1") lasting 30 minutes on the theoretical issues developed during the course;

2) a computer test ("Part 2") lasting 90 minutes, which involves 3D modeling and "constructive commissioning" of an assigned component;

3) a final interview in which will be dealt with issues addressed in the written part and the verification of the models and tables created and / or assigned during the course. The student can choose to continue with a question of theory if he intends to improve his voting proposal (only if he is more than sufficient: 18/30). Failure to check the tables taken during the course will cancel the exam completely.

The passing of the initial test (the minimum grade will be defined from time to time based on the complexity and the number of questions) allows admission to the written test.

Part 1 and eventually Part 2 will be held in the same location (PC) in a computer lab. The conclusive interview can be fixed following the written or other date (with communication at the end of the written). If it is the same day, a period of time will be required that varies from the number of the appeal to correct the written tests.
Registration for the exam takes place through AlmaEsami [http://almaesami.unibo.it].

Teaching tools

Lectures in the classroom.

The course includes the use of computers in a computer lab equipped with a 3D CAD system for parametric solid modeling and automatic commissioning.

Links to further information

Office hours

See the website of Alfredo Liverani