Basic technical drawings course – Level1

Dear makers, designers and 3d lovers,

We are going to increase our projects and our designs.

It means, also, that the skills required to realize our projects need to be increased.

We would like that our projects can be read from everyone of you. For this reason, we are going to make this course.

We would like to do it written and not with an illustrative video because we would like that you can keep this pdf file and that you can use it everytime you want.

SUMMARY:

1. Introduction

  1. Lesson 1
  2. Lesson 2

1. I NTRODUCTION.

We decide to divide this course in 2 lessons. In this course we won’t tell you every singular normative that you can find, but we will give you just basic skills to read our drawings. We follow the UNI EN ISO normative so, if you are from America, the lesson 1 can have some different orthogonal projections.

Here I will write you the topics that we will find, so in this way you already know if this lessons are not for you. We would like to make an advanced course in future.

Lesson 1:
– orthogonal projections
– continue lines
– dashed lines
– technical drawings cartouche Lesson 2:
– sections
– quote
– meaning of Ø
– chamfers quote
– simple tolerance

2. LESSON 1

I designed a simple thing. From this 3d thing we will make our first  2D technical drawing

Let’s start!

Here there is a simple technical drawing,

Orthogonal projections

The first thing to understand are the orthogonal projections.

Watching the 3d model, you can easily understand the thing that is represented. Now, starting from the arrow A, try to have a look to the continue lines that you find in that direction. Imagine that you are to the tail of the line and that you are looking the piece with the same direction of the arrow. Witch line will you see for first? Well, that lines are represented on the right in the pic called A.

Now, how to represent the other 3 views? Imagine seeing the thing from the right zone of “pic A”. What are you seeing now? You will see exactly the “pic B” (this is a bit complicated if it’s your first time that you’re seeing in this way but will be common in future. If you didn’t understand well, read again and see the pic).

A common question that born now is: why “pic B” is on the left?

To answer to this question, you need to know something more about normative, but I will not go in the detail. I can just tell you that in ISO EN UNI (European) normative you will find it on the left, in ANSI (American) normative it will be on the right.

Now, how to represent the “pic C”? Well imagine seeing the thing from the top. What will you see? You will see exactly the “pic C”.

Dashed lines and continuous lines

Lucky way, this point is enough simple to understand for most normative with the continuous line you represent the lines that you see; with the dashed lines you represent the zone that are on back and you don’t see.

A common question is: why don’t we represent all the dashed lines?

The answer here is really simple. That’s because you see before the continuous lines.

Technical drawings cartouches

You can see it the bottom on the right. It’s really common for technical drawings, in that zone there are info about materials, departments, author, company, normative and other technical info that you will need.

LESSON 2

Welcome to the lesson 2! If you didn’t understand well the lesson 1, please read again the lesson 1 and then start reading the lesson 2.

In this lesson, some things are a little bit more complicated, but don’t worry! Together we will learn it easily.

Let’s start!

I designed a simple thing to make our second technical drawing together. Down you will find the technical drawing and we will discuss about what is written on that one.

Sections

Watching the pic on top left, you will find one “dash and point line”. This line, in this case, is the knife that is cutting the thing that is represented. I know, this point can be a bit complicated to understand, but now imagine taking the 3d model and to cut it exactly in the middle. What you will see? You will see the thing down the pic called  A-A (1:1).  

How a section is represented? For first, you will see the 2 arrows on the “dash and point line” and next to that arrows you will read 2 letters, for example A. Then on the section drawing you will find a zone that bring again that letters. Next to that letters you will read also the scale. So, it means that you will read A-A (1:1). You will also see some dashed lines into the drawing. That represent the cut face.

Some designers, before the letters, use the word SEZ. That’s because it gives a simple lecture to the worker.

Why we use to make sections? We do it because it to give more info about the internal part of the product. In fact, if we represented just the external part with orthogonal projections, you will not have any info about internal components.

Quote

Quote is an important topic to talk about. In every drawing you can find the quote and that’s because it’ll give you a lot of information about sizes.

The first thing to understand is the “quote line” it is the line that you see next the drawing where the quote number is written. This quote line is really important, because, thanks to the arrows, you can understand from/to the size written is take.

Quote number is another topic that is really important. You can find just the number or the number with some other signs. If you find it alone, it means that you are just taking the size exactly like when you take the measure with a ruler. In the next point we will talk about the signs that you can find near the quote number.

 Meaning of Ø

If you find this sign, it means that we are talking about a cylindrical thing. The size is a diameter. It also means that you will be able to made it thanks to a milling machine or a turning machine. This is really important because if you see just the pic on top-left, you can understand that you are talking about a cylindrical thing, if you didn’t find it, the thing could also be a solid thing. So in conclusion, Ø =diameter.

If we are talking about a radius, near the quote number you will read R=…..  So in conclusion, R=radius

Chamfers quote

Reading the chamfers quote, you will read 2×45°. The number 2 means the size of the quote line. 45° is a quote that shows the degree of the chamfers. So if you’re making this thing with a turning machine, you need to rotate the tower to 45°.

Simple tolerance quote

Before talking about tolerance quote, I want to tell you something about tolerance.

These are really important for mechanical design, thanks to this quote you  can have some junctions joint or some other junctions with play.

There are many ways to write the tolerance quote, the most common you will find are H7 or h7. But these kinds of tolerance quote need many technical info about normative. But I will talk about the simplest one.

In our  drawings, next the quote number, you will find +0.01 -0.01, it means that the error that you can do during the processing can go over 0.01 mm. for example if the quote is 19+0.01 it mean that the maximum number of the size that you can find will be 19.01 and if you don’t respect it there is an error.

Thanks to all of you that will read our first basic technical drawing course. We really appreciate it!

If you have some feedbacks or you want to have some more technical info or for some collaborations, you can write us on: info@eidos3d.it

To see the next project and to support us, follow us on Instagram @eidos3d .

www.eidos3d.it

Contact: info@eidos3d.it                                               

Designer: design@eidos3d.it

Marketing: marketing@eidos3d.it

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