The technical drawing - Definition - Basic rules - Drawing software - Sketches and hand drawings

Oct 29, 2026

The technical drawing provides the detailed information required to analyze an object, support its design, and facilitate construction and handling before manufacturing. It can be produced with computer tools, and manual instruments like straightedge, square, and compass. The tutorial emphasizes strict rules such as respecting scale, matching views, and using continuous or dotted line types and proper thickness. It also explains cartridges, line conventions, dimensioning and quotations, and practical CAD and sketching workflows.

LanguageEnglish

CategoryTechnology

FormatPDF

Pages7

Reading Time18 min

AccessFree to download

Table of contents

Definition

Basic rules

Drawing software

Sketches and hand drawings

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The technical drawing | | EPFL-IPHYS | EPFL SB IPHYS Luc Chevalley | | | --- | --- | --- | --- | --- | | |
Table of contents:
1. Definition
2. Basic rules
3. Drawing software
4. Sketches and hand drawings | | | | | 1. Definition of the technical drawing
The technical drawing is a detailed representation of an object before its construction.
Its purpose is to provide the information necessary to analyze the object, to help in its design and to facilitate its construction or handling.
The technical drawing can be developed with the help of computers; some software allow projections and calculations to facilitate the drawing. Regarding manual instruments, as it is quite possible to do it with a pencil, the most usual are the straightedge, the square and the compass.
The technical drawing must respect several strict rules: respect of a scale, correspondence of the views, use of continuous or dotted lines; and the goal of this small tutorial is to remind it.
This will greatly facilitate the making, the understanding of the piece, as well as the discussion around a project. As they say: a picture is worth a thousand words. | Basic rules
There are 3 distinct parts to a drawing:
1. The cartridge
2. The drawing itself
3. The quotation | | EPFL-IPHYS | EPFL SB IPHYS Luc Chevalley | | | --- | --- | --- | --- | --- | --- | | | |

| | | | | 2. Basic rules
The cartridge
The first part is called the cartridge (usually located atthe bottom of the sheet) . It informs the reader about 5 essential elements:
1. the name of the piece
2. the number of piece to be made
3. the material of the piece
4. the scale used for the drawing
5. the name of the designer and his laboratory
The cartridge may of course have other information but the 5 points above are basic. | Example of a cartridge: EPFL-IPHYS EPFL SB IPHYS
Luc Chevalley | | | --- | --- | --- | | | | | | The drawing
Several types of lines are used in a technical drawing:
• Continuous lines
• Interrupted
• Mixed
These can be of different thicknesses depending on their function:
• Thick line 0.5 mm
• Thin line 0.3 mm)
Here is a small summary table for your information:
Line Désignation General applications Thickness Continu thik • Contours view
• Arrests views 0,5 Continu thin • Geometric constructions
• Dummy edges
• Dimension lines
• Attachment lines
• Marker lines
• Hatching
• Folded section outlines 0,3 Interrupted • Hidden contours
• Hidden edges
• Hidden geometric constructions 0,3
Line Designation General applications Thickness Mixed thin • Axes of revolution
• Drawing of symmetrical planes
• Trajectories 0,3 Mixed thik • Indications of surface lines subject to particular specifications 0,5 Continuous thin by hand • Hidden contours
• Removals of views 0,3 Contnu thin straight zigzag 0,3 | Example of lines on a drawing
Continuous lines 0.5 (visible lines around the part)
Interrupted lines 0.3 (hidden edges)
Continuous lines 0.5 and 0.3 0.5 for the drill hole
0.3 for the thread
Interrupted lines 0.3 (hidden edges)

Continuous lines 0.5 (visible lines around the part)

| | --- | --- | | | | EPFL-IPHYS | EPFL SB IPHYS Luc Chevalley | | | --- | --- | --- | --- | --- | | The quotation
It allows to transmit the dimensions of the drawing without taking direct measurements on the plan and thus avoid errors due to the printing scale of the drawing or simply measurement errors.
It is thus essential for the good realization of the part.
It is essential to dimension each element of the drawing so that it does not miss a dimension or a positioning during the manufacturing of the part.
If a value is missing, this will delay the production of the part. We will have to stop the machining of the part and contact the designer again so that he can provide us with the missing value.
It is

FAQs

What is the main purpose of a technical drawing?

A technical drawing represents an object in detail before construction to provide the information needed for analysis, design, and facilitating construction or handling.

What strict rules must a technical drawing respect?

It must respect scale, ensure correspondence of the views, and follow the required use of continuous or dotted lines.

How do dimensioning and quotations help during manufacturing?

They transmit the necessary dimensions without direct measurement, avoid errors from printing scale, and ensure each element has correct dimensions and positioning, including geometric tolerances.

Oct 29, 2026

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