Modeling a CPU case

Lesson 5 Modeling a CPU Case This lesson illustrates how to create the external case of a Central Processing Unit using the following commands. • NURBS curves. • Pipe. • NURBS surface editing. • Trim. • Edge extract. • Snap to Point / Snap in 3D. • Coons.

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You will start modeling by drawing the base curves.

Building the case 1) If you are already working with solidThinking, from the

File menu, select New and Save the scene you were working on. Otherwise, you must first run solidThinking.

2) Choose the default layout option from the Layouts panel

(choose View4Layouts).

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Modeling a CPU case

3) Select the NURBS curve tool and create a curve in the Front view for the front profile of the workstation. Try to keep as few control points as you possibly can.

Point coordinates: #1(-5, 0, 0); #2(-5, 0, 3); #3(-4.4, 0, 3); #4(-4.4, 0, 4); #5(-4.4, 0, 13); #6(-3, 0, 14); #7(-2, 0, 14).

4) Select the NURBS curve tool and create a curve in the Top

view for the upper profile of the workstation. Insert the points listed below and use the image below as a reference guide.

Just as before, try to keep as few control points as possible.

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Point coordinates: #1(-5, 12, 0); #2(-5, 11, 0); #3(-5, 0, 0); #4(0, -2, 0); #5(5, 0, 0); #6(5, 11, 0); #7(5, 12, 0). The curves you have created should be similar to those in the figure below.

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Modeling a CPU case

5) Click the Pipe icon. Click the front profile curve, followed by the top profile curve. Note: If the surface you have just attained is slightly different from the one shown in the figure below, you need to act on the two curves that generated the surface (the Construction Curves). Click the Edit Mode icon in the Application Toolbar and drag the curves’ points with the mouse. solidThinking adjusts the surface accordingly.

6) To create the front part of the workstation, select the surface and click the NURBS surface editing icon. An alert panel warns you: The selected surface is part of a Construction Tree. In order to edit with this Modeling Tool, the surface needs not to be a part of the Construction Tree. Do you want the surface to be set as hidden and a copy to be created for editing? Click Yes to confirm your choice.

Note: When you apply the NURBS Surface Editing action, the Construction Tree is broken. The original parametric surface is hidden from the 3D views, but still displayed in the browser. The newly created NURBS surface is NOT linked in any way to the original parametric one.

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Thus, modifying the shape of the original parametric surface will NOT cause the NURBS surface to change its shape accordingly.

7) Click the Edit Mode icon in the Application Toolbar.

8) Hold down the mouse button and drag in the view to select any

point included in a selection box. You can keep the CTRL key pressed to add any ulterior points to the first selection.

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Modeling a CPU case

Note: Selecting points is easier by simply orbiting the camera in the Perspective view.

9) Disable X and Y and click the Translation tool to move the

points downward. Once moved, deselect all of them and move only those needed to get your final shape.

Note: Getting a surface identical to the one below is unnecessary; the issue here is understanding how the command works.

Let’s now move to the upper side. This area is not flat as it may appear, but rather puffed up.

10) Select the points, switch to Edit Mode and Translate the

points onto the Z axis. You will so get a lightly rounded surface.

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Here is the surface viewed in Shade mode (Perspective window) after the translation of the points upwards. You can now distinguish its actual shape.

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Modeling a CPU case

Creating a slot

Let’s create a simple slot.

1) Enable X and Y dragging. 2) Click the Front view and click the NURBS curve icon.

Draw a curve as illustrated below using:

Point coordinates are: #1(-1, 0, 2); #2(-1, 0, 1); #3(-1, 0, 0); #4(0, 0, 0); #5(1, 0, 0); #6(1, 0, 1); #7(1, 0, 2). The curve must be translated through 13 units along the Z-axis.

This curve will now be used to trim the surface.

3) Click the Trim icon. Select the curve to cast and then the

surface. The outcome should look like the figure below.

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Note: The Trim modeling tool allows you to determine the area of the surface you want to keep. In the Modeling Tool panel, activate the appropriate radio button to specify if you want to Keep exterior or to Trim exterior.

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Modeling a CPU case

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You now need to close the trim hole.

4) With the trimmed surface selected, use the Copy and Paste command to create a copy of the object.

Note: The World Browser emphasizes the duplication of the object by adding a new object to the list.

5) Select the original trimmed surface again (not the copy) in

the World Browser and, in the Modeling Tool panel, enable Trim exterior under Loop exterior to highlight the inner portion.

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Closing the case

T

1) extract icon and click the left border to extract it. Do the same with the right one. You will obtain two separate curves. The figure below shows you the edges to be extracted.

o create the lid, we must extract the necessary curves.

Click the Edge

Modeling a CPU case

Note: You will find it easier executing Edge extract in the Perspective view.

2) Do the same to extract the edge relative to the frontal portion.

Refer to the below image.

You now have three profiles. Only the fourth is missing. Next, you will build the surface that will close up the CPU case.

3) Select Edit 4 Active Snap4Point and Edit4Active

Snap4Snap in 3D. The active snaps allow you to create a precise curve.

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4) Click the Top view and click the NURBS curve icon to create the fourth and last curve. Click the two points indicated in the figure below.

5) We will now use the Coons surface creation tool, which

creates a surface blended between four boundary curves. Click the Coons icon and consecutively pick the four curves (1, 2, 3, 4), which define the perimeter of the surface to be created.

1 2

3

4

Modeling a CPU case

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Once you have completed this last surface, your CPU case is ready.

We encourage you to repeat this lesson until you feel comfortable with the concepts and commands explained up this point.