Digital Fabrication

3D modelling involves creating a representation of a 3D object with software. It can involve manipulating polygons, vertices and edges in a simulated 3D environment.

There are many different software applications for 3D modelling, from simple to extremely complex. Some are oriented towards creating models for objects to be printed, while other applications are oriented towards creating models for animation.

Tinkercad

The software we will be using in this class is Tinkercad. It is free, with a web based interface. Tinkercad has been designed to be easy to use to both create models and to export in a format that can be printed.

To use Tinkercad, you need to create an account for Autodesk, the company that makes the software. Click here to set up an account.

Tinkercad has many useful tutorials that are quite helpful when you are learning the software. This tutorial, Let’s Learn Tinkercad, walks you through navigating the workspace, moving rotating and scaling objects, making and manipulating groups and using the align tool. It is a good place to start.

This page will cover some basics of the workspace and some simple instructions to get you started. It is highly advisable for you to work through the Tinkercad tutorials as well. While Tinkercad is relatively simple for 3D modelling, it uses the terms as well as some of the methods of creating, revising and viewing 3D models.

Starting a design

When you have created an account, there is a home page with a menu on the left side with your user name and icon, and buttons marked 3D Designs, Circuits and Lessons. Click the button labelled 3D Designs, then click the button marked Create new design.

You will be in the workspace of Tinkercad. The grid, graph paper-like plane is called the workplane. Your view is called the camera.

Navigating the Tinkercad interface

On the left side, there is a view cube and icons for setting the view to home, zooming in and out, and other viewing functions. Clicking on the view cube changes your view of the workplane: front, top, left, right, bottom. Try clicking the view cube and seeing how the orientation of the camera changes.

The shape menu is on the right hand side of the interface. This shows you the primitive shapes that you can select and drag to the workplane to combine and revise to create your models. Scroll through the menu to see all of the shapes, there are many.

Drag a box to the workplane. Use the view cube to look at each side. Try clicking the home and all the other icons in the menu on the left to see how it changes your view. You can also zoom in or out with the trackpad if you are using a laptop. If you are using a mouse, zoom in or out with the track wheel in the center of the mouse. You can pan left and right by holding down the right button of your mouse and dragging. By holding down the scroll wheel and dragging, you can reposition the camera.

If you have a shape on the workplane and it is selected, on the top right side, you will see the shape menu. This menu tells you many of the properties of your shape, such as whether it is a solid or a hole, the length, width and height.

Translation: moving along the X, Y and Z axis

When you move an object in 3D space without rotating or scaling it, that is called translation.

• Moving an object left to right is translating it along the X axis.
• Moving an object front to back is translating it along the Y axis.
• Moving an object up or down on the workplane is translating it along the Z axis.

When you drag a shape in the workplane, you will see the numbers that indicate how far you have translated the shape, in centimeters. You can click on the shape to select it, then drag it forward, backward, to the left or right.

If you want to move an object up or down, click on the black arrow at the top of a shape when it is selected. You can move it above or below the workplane.

Rotating an Object

You can rotate an object around its 3 axes: X, Y and Z. When an object is selected, you can see the rotation handles for these axes. If you move over the handles with the cursor, you will see the rotation protractor, showing you the possible degrees of rotation for that axis.

The Z axis is perpendicular to the workplane, it is relatively intuitive to rotate on that plane. The X and Y axes can be more confusing. Rotating along the X axis rotates a shape left-right. Rotating along the Y axis rotates an object front-back.

If the cursor is placed inside of the protractor, the shape will be rotating by 22.5 degrees. If the cursor is outside of the protractor, the shape will be rotated by 1 degree.

Try rotating the shapes in all three axes.

Scaling an Object

When an object is selected, you see 5 white squares and 4 black squares arranged around the object. These are the scaling handles. Move the cursor over them. If the cursor is over a black handle, you see the dimensions of the object along the X or Y axis. If you put the cursor over a white handle, you see the dimensions for both the X and Y axes, Put the cursor over the white handle at the top, and you will see the dimension for the Z axis.

Click on the white handle at the top and scale your object up and down.

Next click and drag on one of the corner white handles at the base of your object and scale both the X and Y axes.

If you want to scale only in the X or Y direction, you can click on one of the black handles at the base and scale that way.

If you wish to scale proportionally, hold down the shift key, then grab any handle and drag. If you wish to scale around the center of the object, hold the alt key on Windows, command on a Mac. If you wish to scale proportionally about the center of an object, hold down shift and alt on Windows, shift and option on a Mac.

Skew by Rotating and Scaling

Sometimes you want to make a shape that doesn’t exist in the shape menu. By rotating and scaling an object, you can create new shapes. Try creating a parallelogram- how would you do it?

Grouping objects

Most objects are made of a combination of shapes joined together. Let’s combine a few cylinders of different scales.

First, drag a cylinder to the workplane. Scale it proportionally, by holding down the shift key when you drag on one of the white corner handles, so it has a diameter of 30 cm. Then set the height to 5 cm by clicking and dragging the white handle at the top of the object.

Next drag another cylinder over from the shape menu.

Scale the diameter to 15 cm (remember to hold shift down while dragging), then scale the height to 5 cm.

We want to make a copy of the smaller cylinder. There are many ways to duplicate a shape in Tinkercad. One of the simplest is to select an object, hold the alt key on Windows or the option key on a Mac, and drag. You will drag a copy of the original shape, position it at the other side of the large cylinder.

Now let’s group the shapes together. Make sure that all of the shapes are selected.  At the top of the window on the right side of the interface, there are a number of icons. The icon below is the icon for grouping the selected objects. Click it, and the shapes on the workplane that you have select3ed will be grouped ihnto one object.

Combining Solids and Holes

A 3D object may consist of positive and negative shapes. A negative shape is known as a hole. While building models, you will be combining shapes and grouped shapes with holes, to add hollow spaces to your model, for instance. Let’s add a hollow to the model we have created.

Drag a sphere to the workplane and position near the middle of the model.

Resize the sphere to 10 cm in the X, Y, and Z axis. Click on the black arrow and pull the sphere up 2 centimeters.

With the sphere selected, you will see the Shape Panel. There is an icon for Solid and one for Hole. Click the Hole icon. the object changes to a hole.

Aligning Shapes

As we have seen, creating complex shapes involves combining basic shapes. Perhaps you might need to align shapes to each other before you group them. This is easy to do in Tinkercad.

First select the shapes you want to align to each, by dragging over them, or shift clicking. Next click the Align icon at the menu on the upper right of the interface.

You will now see dots or handles around the selected objects that indicate how you might want to align your objects. There are handles on the X, Y and Z axis. You will see a preview of what it will look like when you click the handles when you roll over the handles.

When you click on the handle, the shapes will align along that axis.

Flipping shapes

Flipping shapes can also be very helpful when you are creating a model. To flip a shape, select it, then click on the Flip icon on the upper right side of the interface.

The object you have selected will have handles that look like arrows indicating the way the object will be flipped along the X, Y, or Z axis. If you roll over one of the arrows, you will see a preview of how the object will be flipped.

Once you click on the arrow, the object will be flipped.

Exporting

In order to print your model, you must export it from Tinkercad. You can export it as an .stl or .obj file. In most cases we will probably use .stl files to print.

To export, click the export button in the upper right menu. When you roll over it, you may see a tooltip.

Next there will be a dialog box with buttons where you can choose to save your file as an .obj file or .stl file. Choose .stl.

One more dialog box will appear. Click OK. Now your file is ready to be printed.