ChemEng stuff followers

Things to set in AutoCAD

 In this post, I am going to cover the key settings to use when first using AutoCAD, such as units, page setup, and other features that help a lot with drafting.

Things to care about in AutoCAD

... the first time. However, most of the time, software packages like this have a default configuration that meets most users' needs. Here, I shall talk a little about how to modify and go along with such settings.

Planning is key

Before starting your drafting, it is desirable that you have, if not as a by-hand sketch on paper, at least in your mind, the whole picture. You should remember that this is an engineering software, and if you do not have a proper system, the result may not be as good as needed.

Among the things you need to think about, I can recommend the following,

  • Drawing size.- You need to visualize whether the whole drafting is to be placed on a single sheet of paper or if more than one sheet of paper is needed. What paper size?
  • Units.- What is the unit system you use? Or, even better, what unit system does your contractor require?
  • Deliverables.- Are you required to provide different views with certain features? Do you need to provide data tables with information about the draftings? Are the deliverables part of a larger project?

The scaling problem

The usage of scale is common to some engineering fields, such as civil engineering, and in architectural projects. However, you can overcome the scaling issue by incorporating dimensions into the drafting, making the process a bit simpler. This is why a number of draftings of mechanical and chemical engineering are not created using a scale.

However, you still need to maintain proportion across all components of a single draft and warn the engineer using the draft that the work is not scaled. Sometimes a part of a machine is too small relative to other components on the same sheet of paper, so drafters magnify the smaller components to aid appreciation of the details. It is in these cases that proper dimensioning and warning labels pay off.

On the other hand, even without scaling, you sometimes need to use a specific scale because of the default line-type features. There is a minimum length for a line section to show its features (dashing, dot-dashing, etc.), so you need to make your drawing a bit larger so the lines are easier to identify.

The unit system problem

In AutoCAD, you choose among four unit systems (say): architectural, decimal, engineering, fractional, and scientific. For engineering, I think decimal and engineering systems are the ones to pay attention to.

Fig. 1 Drawing units box to choose among the different unit systems available in AutoCAD


In decimal units, you can choose among the most common units for length in mechanical and chemical engineering and set a desired precision, which, of course, depends on the drafting requirements. In this very same box (see Fig. 1), you can also set the units for angles and precision.

The main difference between the decimal and engineering systems lies in their presentation. In engineering, two units are given: one for long distances in feet and another for short distances in inches. This is, when referring to, for example, 3.5 ft, in AutoCAD you would write 3' 6" (3 ft and 6 in).

I find the decimal system more tractable, but, to tell the truth, it is just a matter of getting used to it.

You can choose your preferred system by following the path shown in Fig. 2.

Fig. 2 Path to access the Drawing Units box


Model and layout

Here is an important thing for you if you are new to AutoCAD. All drafting is performed in the so-called Model canvas (also called lienzo in Spanish) tab, while drafting ready for printing and delivery is handled in the Layout tab.

You can switch between the model tab canvas and one or more layouts in the bottom-left corner of the window.

Fig. 3 Here are the tabs to switch among model and layout tabs


There is only one Model tab since it has virtually unlimited extension. In there, you can draw minuscule and gigantic stuff. Do not worry about space. On the other hand, there are several layouts, since larger and more detailed drafting projects require deliverables that show key details for reviewers and final commissioning. This is: each layout counts as a sheet of paper.

The grid tool

This is just as in Paint, it is an assistance grid to guide you while drafting and to give you some sense of orientation and verification. The grid is gray so it does not interfere with visibility.

You can adjust and deactivate the grid by accessing the controls in the bottom-left corner of the window, as shown in Fig. 4.

Fig. 4 Grid settings in AutoCAD


In my case, I do not modify these parameters and use the software's default settings. However, it is obvious that when drafting things of the same size and precision, a convenient grid design could be more comfortable.

Snapping things

AutoCAD has a tool called snap, or, better said, a mode. This mode helps you when joining lines or the like. For example, to start a new line at the end of an existing one in the canvas, just position the cursor at that point, and that's it. However, there are cases in which it does not occur: the two lines are not joined.

When you activate the snap mode, AutoCAD is forced to join the two lines when the cursor is placed at the end of a line or another designated position.

Fig. 5 Activate and deactivate the snap mode


I recommend that you activate it. It is a way of avoiding undesirable mistakes. Once the snap is active you can also set some useful preferences in AutoCAD. You can do that with the buttons shown in Fig. 6.

Fig. 6 Snap settings


You can choose the points at which the cursor in AutoCAD is going to be tracked. The first button serves as an orientation tool, turning reference lines on and off, which are useful in the absence of rays or construction lines.

Creating other views of a 2D draft

Well, drawing on a plane gives different details on the object to be manufactured or commissioned. However, perspectives provide useful insights for the drawing's final users, say, those who will build, manufacture, install, etc.

In drafting, there are several perspectives,

  • Isometric
  • Dimetric
  • Trimetric
  • Oblique

AuoCAD offers the isometric option, which can be activated as shown in Fig. 7.

Fig. 7 the isometric view options


Depending on the perspective of the drawing, you can choose among drafting from above, from the left, or from the right. No matter which option is selected, all previous settings work perfectly, and even the grid is adapted to the new environment.

This is the end of the post. I hope you find it useful.

Any questions? Write in the comments, and I shall try to help.

Other stuff of interest

No comments:

Post a Comment

Subscribe to: Comments (Atom)

Most popular posts