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- Download this template file with the shape and size of the Arduino Micro if you need a reference to start off with. It is always good to measure things in real life, because it is inspiring to get hands-on experience.
You need to draw a surface where the Arduino Micro will rest. We will draw it from above and extrude the shape to a box. We will be using the "Part design" workbench.
The size of the Arduino Micro PCB is 48.5 mm x 18 mm. Let us give the pcb a little bit of space on each side. Let say 0.5 mm on each side. We need walls, so add another 1.3 mm on above, beneath, to the left and to the right of the PCB. Which give us a final size of 52.1 mm x 22.1 mm.
- Make a sketch on the XY-plane and draw that shape of the surface
- Add constraints to your drawing to make it exact.
- Exit the the sketch when you are done with it.
- The base of the box needs a thickness, so that it becomes a box. Use the pad tool to do this.
- Set the first length to about 7 mm (upwards) and the second length to 9 mm (downwards).
I linked all special words and functions which I use, to the FreeCAD manual. This is good for the beginner, who knows nothing about FreeCAD and for the Intermediate, user who just wants to do the tutorial fast. I also recommend that you take a look at our last tutorial, where we go through each step in detail when using FreeCAD.
Make two holes in the box. One on the top and one on the bottom. The hole should be "cutting" towards the micro. It should cut just below the Micro, so 9mm will work just fine. The hole on the bottom can have a length of 6 mm.
- Click on the surface you want to cut in.
- Draw the shape of the hole that will make the "walls" of the box.
- If you choose the wireframe from the drawing style menu it is easier to see the objects inside the box.
- Add constraints.
- Exit the sketch.
- Choose the pocket parameters under "tasks".
- Choose the length of the cut. You can also decide in what direction you want to cut. But the standard setting is towards the surface you drew on earlier.
- Click "OK".
TIP: If you make a "pocket" into an object. The surface you draw on acts as a sketch paper or plane. The edges that make up the surface can be used as references for your shapes to get the aligned with the surface in a correct manner. Use the "external geometry" on the edges of the surface you are drawing to enable these as reference lines.
Use the same technique as you used in the previous step.
- Click on the surface you want to cut into.
- Draw the shape of the hole for the usb-connector.
- If you choose the wireframe from the "drawing style" menu it is easier to see the Arduino Micro inside the box.
- Add constraints.
- Exit the sketch.
- Choose the pocket parameters under "tasks".
- This time you can choose "To first", under "type". This cuts all the way through to the first "stop" or "wall".
- Click "OK".
I want the pins on the bottom of the Arduino Micro to be able to pass through the shelf in the box. So that we will get a nice looking box without any pins or wires sticking out.
We do this in the same manner as we did the hole for the USB.
- We select the surface of the shelf from the top of the model. If you are uncertain which side is up and down, press zero on your keyboard to return to the standard isometric view of the model.
- We draw two boxes near the edges of the surface that will act as slots.
- Here we can use the "external geometry" tool in combination with the constraint tools to position our slots at the exact desired length from the edges. My slots were 1mm tall,left and right outermost edges were 1.6 mm from the edges of the surface. The top line of the top slot where 1.6 mm from the top edge and the other way around with the bottom edge on the bottom slot.
- When you are done, exit the sketch and use the pocket tool in the tasks tab to make the slots into 3D slots through the surface. In the pocket parameters, you can choose the "to first" alternative in the "type" drop down menu.
TIP: If you press the 0 through 6 buttons on your keyboard you can choose 7 different standardized views.
On this box we need two lids and these have to be fastened somehow. I solved this by adding two grooves on the inside of the walls of the box. I placed the grooves near the edge of the wall, about 1 mm down. This is so that we can put a small hooking mechanism on the lid that snaps into the grooves.
- We draw this in the same manner as the hole for the USB-cable.
- Do not forget to use the external geometry tools to add reference lines from the surface you are drawing on. I find that the distance constraints in combination with the these external reference lines makes it easy to place shapes where you want them.
- Make a new document.
- Add a sketch on the XY-plane.
- Make a rectangle with same size as the base of your box: 51.5 mm x 21 mm.
- Exit the sketch and pad the rectangle, making the basic shape of our lid.
- The thickness I used was 1.5 mm. You can make it thinner if you want. I would not go thinner than 0.8 mm.
- Press the zero button on your keyboard to get an overview of your object. Click on the top surface and start a new sketch.
- Draw a rectangle and another rectangle inside of it.
- Add the constraints as you see in the picture below. Remember to use the external geometry tool.
- Exit the sketch and pad the shape. Make it 2.2 mm tall.
The ledges are meant to snap into the holes on the inside of the box.
- Click on the sides of the extruded edges we made earlier.
- Click create sketch.
- Draw two rectangles on the surface according to the picture below. The ledges are supposed to lay flush against the top edge and you can add a horizontal length constraint of 1 mm on outsides of the ledges.
- We need one rectangular hole and six small round holes to secure the IR-receiver on the lid.
- Click on the flat side of the lid.
- Make a new sketch.
- Draw a rectangle and 6 circles like in the picture below.
- I have put them in the lower left corner.
- You can use the external geometry tool here also to get a reference point from which you can set your constraints. Set your constraints like in the picture below.
- Click close to exit the sketch.
- Click on the "Create a pocket..." button.
- In pocket parameters choose "Thru all" in the type drop-down menu.
- Click OK.
- The LED also needs a hole. We will make a special hole for the LED, because we do not want it to slip through the lid.
- Click on the flat side of the lid again and choose "create sketch".
- Draw a circle with a radius of 2.9 mm.
- You can flatten the bottom part of the LED if you want to and if your LED is flat on one side. The "trim" tool is really handy when it comes to cutting up objects. It can remove according to intersections.
- When you are ready click close.
- Click on create a pocket and set 0.8 mm as a length.
- Click OK.
- Click inside of the hole and start a new sketch.
- Draw a smaller circle with a radius of 0.85 mm.
- Put it somewhere in the middle of the bigger circle.
- Click close and choose create pocket to cut straight through the lid.
To export from FreeCAD to post-processing program for 3D printing, we have to select the body the model we want to export. We can either do this in the Tree view on the left side of the screen or we can click on the 3D object on the screen.
- Go to the File menu and click Export.
- Give the file a name and choose to save it as a STL.
- Open Slic3r.
- Go to the file menu and click on "Load config"
- Navigate to the Tutorial3.ini and click on open.
- Go to the file menu again and this time click on "Quick slice and save as".
- Choose your Stl and where and what you want to save the G-CODE as.
- Put the G-CODE on an SD card and put it in the printer.
- Go to the "Print from SD" menu, scroll down to your file and start it by clicking on it.
- Congratulations! Your custom Arduino Micro case is printing.
NOTE: Don't forget to make sure your 3D printer is healthy and well calibrated.
kengdahl
Arduino_Scuola
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