In this session we will analyze how to build several components for a PCB enclosure.
The acronym PCB stands for Printed Circuit Board.
Many consumer electronics use printed circuit boards and they
often must be assembled in some type of enclosure.
The enclosure contains other important items such as fans, heat sinks,
and sometimes buttons and connectors to allow the user to interact with the electronics inside.
In this exercise we're going to create a few components for the PCB
and modify the enclosure to allow for adequate ventilation.
We’ll start by creating 3 different size capacitors and placing them on the circuit board.
This may sound time consuming, but don’t worry!
We’ve got a great way to make this quick and easy!
After that, we’ll improve the design of the PCB enclosure by adding holes for ventilation.
To increase airflow over the circuit board, some fans will be required,
so we’ll also be placing some mounting holes and creating cutouts for the fans.
We'll then design the fan housings and assemble them.
Lastly, we’ll assemble a heat sync and quickly alter the geometry
to match existing components on the PCB.
Let’s examine the assembly to get an idea of how we can make the necessary changes.
Open the file labeled PCB Exercise File and move to the Model stage.
Look at the main model and rotate it around a bit and note that the enclosure,
which is the box that contains all of the circuitry, has no holes for ventilation.
In the finished design, there would be a lid covering the top of the enclosure,
so the current design isn’t great.
Press Ctrl+2 to orient the model in the Front view.
The circuit board looks a little bit empty.
Our first task is going to be to create some electrical components to add to the circuit board.
Refer to sheet 2 of the technical drawing.
This drawing contains the dimensions to create a capacitor.
A capacitor is a device that stores electrical energy in an electric field,
usually in the gap between metal plates.
If we examine the technical drawing, we can see that our capacitor doesn’t have
any internal structure, so we can think of it as being for display purposes only.
This model is essentially a cylinder with a few minor modifications.
It’s generally advisable to create the bulk of a design in the first few operations,
then add the finer details.
Keeping that approach in mind, we can begin by creating the main cylinder.
The groove near the base of the cylinder can be created with a revolved cut.
Then we’ll add the depressions on the top and bottom faces
and create the radius along the top circumference.
The last step will be to add the 2 pins on the bottom of the capacitor.
Before starting, make sure that in the Display tab the Fade Scene option for the grid is activated.
This will help us visualize the sketches on the grid.
To begin creating the capacitor create a new sketch anywhere in the PCB exercise file.
The orientation of the sketch is not important right now.
The front face of the enclosure is a good place to start.
Select it, press K to activate the sketching mode, and click plan view on the HUD.
Outside the enclosure, create a rectangle 25 mm high and 10 mm wide.
Start the Pull tool and select the rectangular surface.
Click the Revolve option and select one of the long edges
on the rectangle as the axis to rotate about then press enter.
This operation should create a cylinder with a diameter of 20 mm and a height of 25 mm.
Press Escape to exit the pull tool.
For convenience, let’s hide the PCB housing assembly.
Move the mouse cursor over the cylinder and select the dashed center axis, then create a sketch.
The sketch plane should pass through the center of the cylinder.
Select the Circle sketch tool.
Then move the mouse cursor to one of the bottom corners of the cylinder and tap the shift key,
place a circle with the center point 4 mm up from the bottom and 1 mm outside the cylinder.
Set the diameter to 4 mm.
Start the Pull tool and select the circular face.
Select the Revolve tool guide again and select the same axis of the cylinder.
This time select cut from the Pull options on the right side of the HUD,
and click Full Pull to cut a groove around the base of the cylinder.
Click anywhere in the background to revert to the basic pull function,
then hold Ctrl and select the top and bottom edges of the groove.
Use the Pull tool to apply a 1 mm radius.
Press S on the keyboard to exit the Pull tool.
Create a new sketch on the top face of the cylinder.
Select the Circle sketch tool.
Place the center point at the center of the circular face.
Sketch a circle with a diameter of 16 mm.
Repeat this process on the bottom face of the cylinder.
Then activate the Pull tool, select the two circles
and enter -1mm to create a 1 mm depression on each face.
Hold Ctrl and select the two edges at the top of the cylinder.
Use the Pull tool to create a full round.
You can create a full round by clicking and dragging slightly
to begin adding a radius and then moving the mouse in the opposite direction.
If done correctly the two edges should be rounded into one continuous arc.
Now we need to create the pins at the bottom of the capacitor.
On the bottom face of the cylinder sketch two circles each with a 2 mm diameter.
Place one circle 5 mm up from the center and the other circle 5 mm down.
Press P to activate the pull tool and pull the two profiles 5 mm outward to create the pins.
We’re now going to duplicate the solid body using Move Copy.
Start the Move tool
and Select the body then hold Ctrl and click and drag the Move tool in any direction.
Click and drag again to create a 2nd duplicate.
The completed assembly has 3 different sized capacitors.
We can create these quickly using the Scale option within the Pull tool.
First select the top face of the 2nd capacitor and sketch a point in the center.
Click Pull and select the scale body option.
Locate the sketched point and select it as the anchor point.
This is a point that will remain fixed as the rest of the body is scaled larger or smaller.
Click and drag a box around the 2nd capacitor.
Press the spacebar and enter 0.75 as the scaling factor.
This new capacitor is 25% smaller than the original.
Repeat this process to create another capacitor that is half the size of the original.
Use 0.5 as the scaling factor.
Notice how the capacitor moved some distance toward the anchor point
in this case, since it was not on the body itself.
Then press S to exit the pull tool and delete the point.
Select the three solids from the model tree then right click and select Move each to new component.
Change the name of all three components
to capacitor and then add the size at the end of the name.
It would suffice to add L, M, or S to differentiate between large, medium, and small.
Display the PCB Housing assembly.
Use the Move tool to place the capacitors anywhere on the circuit board
but avoid the area near the 3 components furthest from the world origin.
Select a capacitor by triple clicking on it, then
use the Move handles to translate it along the X and Y directions.
Click the Anchor button and select the bottom edge of one of the pins.
Select the Up To option and click the top surface of the circuit board
to snap the capacitor to that position.
Repeat this process for the remaining capacitors.
You can now color the capacitors as you like,
then save the current file.
In the next session we will modify the enclosure to provide adequate ventilation.