{"id":6755,"date":"2020-06-18T13:48:23","date_gmt":"2020-06-18T10:48:23","guid":{"rendered":"https:\/\/fractory.com\/?p=6755"},"modified":"2025-02-14T12:23:07","modified_gmt":"2025-02-14T10:23:07","slug":"engineering-drawing-basics","status":"publish","type":"post","link":"https:\/\/fractory.com\/engineering-drawing-basics\/","title":{"rendered":"Engineering Drawing Basics Explained"},"content":{"rendered":"

An engineering drawing is a subcategory of technical drawings. The purpose is to convey all the information necessary for manufacturing a product or a part.<\/p>\n

Engineering drawings use standardised language and symbols. This makes understanding the drawings simple with little to no personal interpretation possibilities.<\/p>\n

So let’s look at the different line and view types you will come across in the engineering discipline.<\/p>\n

The Purpose of Engineering Drawings<\/h2>\n

As already said, such a technical drawing has all the information for manufacturing a part or welding<\/a> and building an assembly<\/strong>. The info includes dimensions, part names and numbers, etc. So once a manufacturing engineer gets the drawing, he can start the production process without a second thought.<\/p>\n

First, we have to pause for a second and address our own customers here to avoid confusion. The drawings you submit for instant pricing and manufacturing<\/a> in our system do not need any of this. The same applies to 3D models. CAD files and drawings made according to our design tips<\/a> include all the necessary information for making your product. The only time we ask for a drawing is if you want to specify tolerances.<\/p>\n

Still, knowing all the rules and basics of formatting is an absolute must in the industry<\/strong>, as traditional manufacturing companies still need detailed drawings.<\/p>\n

How to Make Drawings?<\/h2>\n

A few decades ago, you would have had to sit down at a drawing board covered with papers of different sizes, rulers, callipers, etc. Today, all these instruments are still good for manual drafting but no contemporary manufacturer really wants such drawings.<\/p>\n

Why? Because most of the machinery uses CNC systems that can read the information straight from the files and produce a cutting program accordingly. Drawings done by hand would just add a lot of manual work for manufacturing engineers.<\/p>\n

So, we are left with only one option really – every engineer should use CAD (computer aided design) software because of its many advantages<\/a>.<\/p>\n

You can, of course, use CAD for making drawings from scratch. But the easier option is to first make a 3D model and create the drawings from that, as the programs generate the views with only a few clicks. All you need to do is add the dimensions. Having models also makes updating the drawings for revisions simple.<\/p>\n

Basic Components of an Engineering Drawing<\/h2>\n

Let’s see what makes up an engineering drawing. A single drawing includes many elements with quite a few variations to each of them. So let’s take a closer look here.<\/p>\n

Different Types of Lines<\/h3>\n

Not every line on an engineering drawing is equal. The different options make it possible to show both visible and hidden edges of a part, centre lines, etc.<\/p>\n

\"continuous<\/p>\n

The most common is a continuous line, also known as a drawing line. This represents the physical boundaries of an object. Put simply, these lines are for drawing objects. The line thickness varies – the outer contour uses thicker lines and the inner lines are thinner.<\/p>\n

\"hidden<\/p>\n

Hidden lines can show something that would not be otherwise visible on the drawings. For example, hidden lines may show the length of an internal step in a turned part without using a section or a cutout view (we explain both later).<\/p>\n

\"centre<\/p>\n

Centre lines are used to show holes and the symmetric properties of parts. Showing symmetricity can reduce the number of dimensions and make the drawing more eye-pleasing, thus easier to read.<\/p>\n

\"Dimension<\/p>\n

Extension lines annotate what is being measured. The dimension line has two arrowheads between the extension lines and the measurement on top (or inside, like in the image above) of the line.<\/p>\n

\"broken<\/p>\n

Break lines indicate that a view has been broken. If you have a part that is 3000 mm long and 10 mm wide with symmetric properties, using a break-out gives all the info without using as much space.<\/p>\n

While a good way to provide information to people, CNC machines need full views to cut the parts<\/strong>. Otherwise, the manufacturing engineer has to reconstruct the whole part from the measurements.<\/p>\n

\"cutting<\/p>\n

When using a cutout view, the cutting plane lines show the trajectory of the cutout. Here you can see that the A-A cutting line brings both types of holes into the view.<\/p>\n

Types of Views<\/h3>\n

So let’s take a closer look at the different types of views that are often present in a manufacturing drawing. Each serves a certain purpose. Bear in mind that adding views should follow the same logic as dimensioning – include as little as possible and as much as necessary.<\/p>\n

A tip for good engineering practice – only include a view if it contributes to the overall understanding of the design.<\/p>\n

Isometric View<\/h4>\n

\"Isometric<\/p>\n

Isometric drawings show parts as three-dimensional. All the vertical lines stay vertical (compared to the front view) and otherwise, parallel lines are shown at a 30-degree angle.<\/p>\n

The lines that are vertical and parallel are in their true length. This means you can use a ruler and the scaling of the drawing to easily measure the length straight from a paper drawing, for example. The same does not apply to angled lines.<\/p>\n

\"perspective
Left – perspective; right – isometric<\/figcaption><\/figure>\n

It is important to distinguish the isometric view from a perspective view. A perspective view is an artistic one that represents an object as it seems to the eye. Engineers stay true to the dimensions rather than optical illusions.<\/p>\n

Orthographic View<\/h4>\n

\"Multiview<\/p>\n

This is the bread and butter of an engineering drawing. An orthographic view or orthographic projection is a way of representing a 3D object in 2 dimensions.<\/p>\n

Thus, a 2D view has to convey everything necessary for part production. This kind of representation allows for avoiding any kind of distortion of lengths.<\/p>\n

\"Orthographic
Orthographic projection (ISO standard)<\/figcaption><\/figure>\n

The most common way to communicate all the information is by using three different views in a multiview drawing:<\/p>\n