How to Create Isometric Drawings in AutoCAD

AutoCAD Isometric Drawings

AutoCAD is significantly different from other computer-aided design (CAD) software such as SolidWorks, CATIA, SketchUp, Fusion 360, Inventor, Creo, and so on. This is because the latter group of applications is predominantly used to create 3D models. And while AutoCAD supports several types of 3D modeling, including wireframe modeling, mesh modeling, surface modeling, and solid modeling, it is primarily used to create 2D drawings and sketches. 

It comes as no surprise then that AutoCAD primarily features flat, sketch-based workflow and drawing tools such as lines, arcs, circles, and polylines rather than spheres, cylinders, and wedges, as is the case with the aforementioned 3D modeling software. But this is not to say that you cannot use AutoCAD in three-dimensional use cases. Far from it. AutoCAD does indeed let you create 3D models as well as create graphic representations of 3D objects, known as isometric drawings. In fact, to create the isometric drawings, you have to use the software’s flat, sketch-based workflow and tools. And in this article, we discuss how.

What is an Isometric Drawing?

An isometric drawing is a representation of a 3D object drawn on a flat plane that mainly contains 2D coordinates – the x and y axes. And although it uses the 2D coordinate system, it gives the illusion that a 3D system is being used. This type of drawing is made up of 2D geometric objects such as lines, ellipses, and parallelograms. And because it is a representation, an isometric drawing is not an actual 3D model. In contrast, and for a better, informative perspective, 3D models are made up of 3D geometric shapes such as spheres, cubes, cylinders, and cones, just to mention a few.

An isometric drawing shows three sides of the 3D object – the top, left, and right. The edges of the object along the left and right faces are tilted/rotated by an angle of 30º to the true horizontal axis. It is worth pointing out that the true horizontal axis is also known as the plane of projection, as the sides are projected outwards from a central reference point on this plane. The angle between the edges of the left and right faces is 120º rather than the normal 90º (refer to the image below). 

Isometric Drawing of a Cube

Isometric Drawing of a Cube (source)

Isometric Drawing vs. Isometric Projection: The Difference

The term isometric drawing is sometimes used synonymously with the term isometric projection. However, while both the isometric drawing and isometric projection represent 3D objects, which may perhaps be the source of the confusion, we want to point out that there is a significant difference between the two terms. The isometric drawing features the same (actual) dimensions as the 3D object it is representing. In contrast, the isometric projection features foreshortened dimensions by about 82%.

Isometric Drawings in AutoCAD

Isometric drawings are not a new concept in the design world. Before the advent and widespread adoption of CAD software, engineers, designers, and architects created these drawings using T-squares, protractors, triangles, and, in some cases, drafting arms. But the process was time-consuming.

Fast forward to the present. Most of the things are simplified. Virtually every design office and school lab is equipped with a computer, with the professionals and students using CAD software to create, among others, isometric drawings. AutoCAD is one such CAD software. And in this section, we will detail how to create isometric drawings in AutoCAD.

How to Open an Isometric Drafting View in AutoCAD?

To create an isometric drawing in AutoCAD, you must toggle on the isometric drafting setting. By default, this setting is off, manifesting in an orthographic model space made up of perpendicular grid lines parallel to either the vertical or horizontal. It is this workspace that enables you to create 2D sketches and drawings. Unfortunately, it does apply to the creation of isometric drawings, which, by their very nature, are supposed to represent 3D objects. 

Toggling on this setting instructs AutoCAD to tilt/rotate the horizontal grid lines by 30º in conformity with the principles of isometric drawings detailed above. You can turn on the isometric drafting (contracted as Isodraft) view/mode using the command line or the Isometric Drafting button. Below is a step-by-step breakdown of how to turn on isometric drawing mode using a button:: 

  1. Hover over the status bar and press the Isometric Drafting button
    This button is denoted by two axes intersecting at an angle. 
  2. Select your desired Isoplane option – left, top, or right.
    The Isoplane option represents the orientation of the gridlines. The left option shows the 90º and 150º axes, the right shows the 30º and the 90º axes, and the top option displays the 30º and 150º axes. (Refer to the image below.)

If you are intent on using the command line, follow this procedure to turn on isometric drawing mode::

  1. Key in the word ISODRAFT on the command line and hit enter.
  2. Select the Isoplane option by typing the letter L for the left option, T for the top option, or R for the right option and hit enter.

In either case, you will notice that the model space will automatically refresh, displaying a new non-perpendicular/angled layout of the gridlines. This signifies that you have entered the isometric drafting view/mode. 

How to Create Isometric Drawings in AutoCAD?

Key Isometric Drawing Commands in AutoCAD

Key Isometric Drawing Commands in AutoCAD

With the correct drafting mode toggled on, it is now time to create an isometric drawing. For the best isometric drafting experience, here are a few tips/pointers, including the main commands used: 

  1. Select the right Isoplane option
    Isoplane Options in AutoCAD

    Isoplane Options in AutoCAD

    The Isoplane Top option, for instance, displays the 30º and 150º gridlines, which correspond to the rotated horizontal edges of the AutoCAD isometric drawing. This enables you to create the bottom and top faces of a 3D object. On the other hand, the Isoplane Left option allows you to create the left face, while the Isoplane Right option lets you draw the right face.
  2. Turn on the ORTHOMODE when drawing geometric objects that are along the 30º and 150º axes.
    This action ensures that all the lines you draw along the 30º and 150º axes are parallel to the axes.
  3. Turn on Polar Tracking when you want to copy/move objects along the 90º axis.
    This comes in handy when you want to create the upper face of the 3D object when you already have an existing bottom face. Simply put, this tip simplifies the creation process.
  4. Suppose you want to create an isometric drawing with a face whose orthographic projection would be a circle, such as a cylinder. In that case, you must use the ellipse drawing tool > Isocircle rather than the circle tool.

To put all these tips into practice, we will detail how to draw a cuboid, three different circles, a cylinder, and an arc in AutoCAD. Let’s dive in.

How to Create an Isometric Cuboid/Cube in AutoCAD?

To create a cuboid in AutoCAD’s Isometric Drafting mode/view, follow the procedure below:

  1. Select the Isoplane Top option, which will help you create the bottom and top faces of the cuboid.
  2. Use the Line drawing tool to draw the edges along the 30º and 150º axes. Ensure you have turned on the ORTHOMODE for greater accuracy.
  3. Turn off the ORTHOMODE and toggle on Polar Tracking
  4. Use the Copy tool to copy the face you drew in step 2 above. If the face drawn in step 2 was the bottom face, for instance, the copy tool enables you to create the top face.
  5. Draw 90º lines that join the opposite vertices of the two faces in order to create a closed cuboid.
  6. Use the trim or erase tool to do away with the lines that are out of view.

How to Create an Isometric Circle (Ellipse) in AutoCAD?

While you can still use the Circle tool to create a circle in AutoCAD, the resultant object will not be tilted, as is the case with other isometric drawings. Instead, it will be orthographically orientated, as shown in the diagrams below. To draw a circle in the isometric drafting view, follow the procedure below:

  1. Press the drop-down arrow beside the ellipse button on the Draw ribbon panel 
  2. Choose the Axis, End option
  3. Next, type the letter I, which represents the word isocircle, and hit enter.
  4. Using your mouse, specify the center of the isocircle by pressing the left button.
  5. Specify the radius of the isocircle by keying in the figure and subsequently press Enter.

These steps apply to the three orientations of isocircles. If you want to create an isocircle on the top face, select the Isoplane Top option.

Isoplane Top Circle in AutoCAD

Isoplane Top Circle in AutoCAD

Similarly, if you want to draw an isocircle on the left face, choose the Isoplane Left option.

Isoplane Left Circle in AutoCAD

Isoplane Left Circle in AutoCAD

Lastly, if you want to draw an isocircle on the right face, select the Isoplane Right option.

Isoplane Right Circle in AutoCAD

Isoplane Right Circle in AutoCAD

How to Draw an Isometric Cylinder in AutoCAD?

 

Object Snap Options in AutoCAD

Object Snap Options in AutoCAD

If you want to draw a cylinder, follow the steps below:

 

  1. Create an isocircle by following the steps described above
  2. Use the Copy command to duplicate the isocircle, creating the opposite face of the cylinder
  3. Next, click the drop-down arrow next to the Object Snap – OSNAP button on the status bar
  4. Ensure you have turned on the Quadrant option from the menu that pops up.
    Alternatively, you can click on Object Snap Settings and use the Drafting Settings window to turn on this option
  5. Draw a line from the isocircle’s first quadrant to the other.

    First Quadrant in Isometric Cylinder Creation in AutoCAD

    First Quadrant in Isometric Cylinder Creation in AutoCAD

  6. Draw a second line from the isocircle’s third quadrant (as shown in the image below) to the other isocircle’s.

    First Quadrant in Isometric Cylinder Creation in AutoCAD

    First Quadrant in Isometric Cylinder Creation in AutoCAD

  7. Use the Trim command to erase arcs that are out of view

How to Draw an Isometric Arc in AutoCAD?

If you are looking to draw an arc in isometric view, follow this procedure: 

  1. Press the drop-down arrow beside the ellipse button on the Draw ribbon panel 
  2. Choose the Elliptical Arc option
  3. Next, type the letter I, which represents the word isocircle, and hit enter.
  4. Using your mouse, specify the center of the isocircle by pressing the left button.
  5. Specify the radius of the isocircle by keying in the figure and subsequently press enter.
  6. Specify the start angle
    You can do this by moving the mouse cursor from the center of the isocircle so that the dotted line drawn intersects with the circle’s circumference (as shown in the image below).

    Start Angle in AutoCAD

    Start Angle in AutoCAD

  7. Specify the end angle by following the description in step 6
    AutoCAD will erase the section of the isocircle that exists between these two angles, creating an arc as in the image below.

    End Angle in AutoCAD

    End Angle in AutoCAD

Conclusion

If you want to draw isometric arcs, circles, cylinders, and virtually any 3D shape, the isometric drafting mode in AutoCAD is an excellent place to start. And in this article, we have detailed how you can create each of these shapes. But before you can go about creating, it is vital to bear in mind that you need to activate the isometric drafting view using the ISODRAFT command or a button. You also have to choose the isoplane option that best works for you. And to help with this, we have included several tips and pointers. Happy drafting!

 

 

 

 


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