Part 6: Completing the Model

In this section, you will complete the model by mirroring the surfaces and creating a cap.

Watch Part 6 of the tutorial.

Opening the tutorial file (optional)

If you successfully completed Part 5, proceed to the next step: Mirroring the surfaces below.

If you were not successful in part 5, open the file called showergel_part6.wire, located in the wire directory of the CourseWare project. This file contains the completed model from Part 5.

Mirroring the Surfaces

Finally, you will mirror all the surfaces using the Layer Symmetry tools.

1. Turn on Symmetry for the Bottle layer using the sub-menu on the layer menu.

2. Click in the layer tab to make the layer active. It will be shown in yellow with a white border.

3. Choose Layers > Symmetry > Create Geometry to convert the mirrored image of the geometry into actual geometry.

To complete the model as a closed volume, add a planar surface to the top of the neck.

4. Choose Surfaces > Planar Surfaces > Set Planar and select the two top edges of the neck. Click Go to create the surface.

Volume Measurement

If you have built your model carefully so there are no gaps between the surface patches, you can calculate the volume enclosed by those surfaces.

For the volume calculation to be accurate, all the surfaces need to face outwards.

As you build you model, you aren't concerned with the surface orientation, and surfaces will randomly face inwards or outwards.

NoteThe Surface Edit > Orientation > Set Surface Orientation tool can be used to show surface orientation (blue shading means that the surface faces outwards, yellow, inwards).

For an accurate volume calculation, you need all the surfaces to face outwards. So you will first unify the orientation of the surfaces.

Preparing the Model for Volume Calculation

1. Make sure that only the bottle surfaces are visible on screen.
2. Choose Surface Edit > Orientation > Unify Surface Orientation . Drag a pick box over the whole model to select all the surfaces.

3. The surfaces are highlighted,

4. Click Classify.

The surfaces are highlighted in blue, and a Unify button is shown.

A blue arrow is also shown, indicating the orientation of the surfaces. This arrow should point out, away from the model. If it doesn't, click it to switch the direction.

5. Click Unify to unify the surface orientations. A message is shown in the prompt window confirming the surfaces have been unified.

Calculating the Volume

Now, you will calculate the volume of the bottle.

1. Choose Pick > Object and select all the surfaces.
2. Choose the Evaluate > Mass Properties tool. The volume is created and displayed in a separate window.

Interpreting the Calculated Volume

The figure given in the mass properties window is in cubic millimeters. Most packaging designs are measured in milliliters.

To make the conversion, divide by 1000.

So, in this example, a volume of 336555 cubic millimeters is 336.5 milliliters.

Also, the volume measured is the external volume of the whole bottle. This will include the liquid, the airspace at the top of the bottle and the thickness of the plastic itself. Making an allowance of 25% is a good approximation of the extra volume all these factors add to the desired product volume.

So, if our target is a product volume of 250 ml, you would expect to add 25% to account for the plastic material and airspace, giving a target of 312.5 ml for the external shape modeled. This would then be displayed as 312500 mm3 in the Mass Properties window.

Revolving a Cap

To finish off the model, you can build a simple cap from curves supplied on the CapCurves layer.

1. Turn on the visibility of the CapCurves layer.
2. Select all the cap curves using Pick Objects on the layer sub-menu.

3. Choose Surfaces > Revolve and double-click the icon to open the option window.
4. In the Axes section, select Global. This enables you to revolve all the curves at the same time around the origin.

5. Click Go in the option window to create the cap surfaces.

6. Assign the new cap surfaces to the CapCurves layer.

The Shower Gel pack design is now complete.