Fusion 360 Laser Cutting Tutorial: Create a sketch for Laser Cutting

Next step is to create a draft shape of the base of the pencil case we want to create. 

This step is to give an approximate representation of the drawing, so don’t bother to be very precise regarding dimensions. 

Click on the “sketch” button.

Let’s start by creating continuous lines to create the outline of the sketch.

Once you are done with the first draft of the sketch, press enter to exit the sketching mode. In this step, the draft sketch looks like this:

In order to convert this draft into the final sketch, we have to apply on it some constraints. It is important to apply constraints to the sketch so that its analogies are locked down. Otherwise the sketch will have a free form that will be affected every time we set a new dimension and the whole design will be changing accordingly.

In this case, the two highlighted lines should be parallel, as the sketch should be symmetrical. So, we have to add the constraint of the parallelism. To do that, select the lines by holding pressed the “Ctrl” button. 

To add the constraint, go on the hidden bar on the right of the board, and select “parallel”.

 Once you click on parallel, the constraint is applied and the sketch looks like this:

Keep adding constraints to all the lines that should be parallel with each other so that you lock the form of the sketch down and eliminate the degrees of freedom in your design.

Once the constraints are applied, it’s time to add some dimensions to lock everything down. To do that, select the line on which you want to apply the dimension and go to the “sketch” tool. From there, select “Sketch Dimension” as shown in the image below:

Now it is possible to add the value of the desired dimension in the box that appears next to the dimension line. Repeat that for all the lines for which you want to define dimensions.

In the end, the sketch should look like this:

Now that the constraints and the dimensions are set, the sketch is completed. To exit the sketch area and move to the next steps, select the “stop sketch button”.

After that, the sketch should look like this: 

Right now the sketch is in 2D. In order to visualize it in the 3D space, we need to add some thickness to it. Let’s add a parameter defining the thickness of our part. Adding parameters is a smart way to define the current thickness of your sketch. If you want to change the thickness of your parts later, you can modify the value of the parameter and it will change automatically.

Moreover, if your sketch contains multiple parts, you can use the parameters you set once for all the parts that you will design for now on.

So, this is a convenient and automatic procedure that makes the designing process less complicated. 

To add parameters, go to the “Modify” tool, and select “Change Parameters”.

A window will appear, asking you to define your parameter.

Let’s name this parameter “thickness” and set it at 2.5 mm. We set this value because this is the thickness of the laser cutting material we will use for producing the part.

To apply the thickness parameter, you have to extrude your sketch. To do that, go to the “Create” button and select “Extrude”.

You will be asked to define the value of the extrusion.

Since the thickness parameter was added at the previous step, instead of a number you can type “thickness”. It is automatically recognised that the value of the thickness is 2.5. 

If you want to change this value, you can do it by editing directly the parameter itself.

Now the 3D sketch should look like this: