3D Design Pt.2

After getting the shape of the top and bottom plate, it was now time to start making the remaining pieces to finish the eclosure.
I started by making the side plates. I decided that the thickness of the box will be 75mm (including the thickness of the wood itself).
I started by making a 204mm by 69mm rectangle. Then I added teeth on the top and bottom that would perfectly align with the top and bottom plate. And finally, made teeth on the sides to mount the side panels.
With the teeth, the rectangle's dimensions become 210mm by 75mm, just like I wanted them.

And finally, I made the front/back panels. I started off with a 291mm by 69mm rectangle, and then added the teeth that would once again align perfectly with the top/bottom and side panels. And again, the rectangle's dimensions become what I wanted them to be : 297mm by 75mm

And all of the new teeth were made with an extra 0.15mm in width so that I can compensate for the laser machine's tolerance.
Having to manually make the teeth and take dimensions for every side of every plate made the process a bit painful and time-consuming. I had to precisely measure the distances from previous parts, and know exacly how to place these dimensions in the new parts and correcly use the features. I would say that it needs some experimenting to get to the result wanted. Especially since I didn't know any rules about how to make the teeth. And the extra 0.15mm of width for each tooth forced me to find a way to override the "Linear Sketch Pattern" function in Solidworks so that I don't offset the other teeth.
I ended up by using that function to duplicate the teeth and have some approximate measurements, and then spaced them by using their lengths' midpoints.

And after all of the enclosure's plates were ready, I went on with making an assembly to see of everything fits correctly.

And fortunately, everything fits perfectly without building errors of design errors !

3D Design Pt.1

After 2 days of having discussed the project's features, I started working on the 3D Design.
And before getting into Solidworks, I decided to make this project on some 3mm MDF wood, as it will be light. And this decision should be made before starting the design, as the mounting teeth should be designed according to the wood's thickness.

First of all, I started by making the upper part. I made a rectangle with mounting teeth 3mm thick, and then saved a copy of it for the bottom part, as they have the same base shape. And including the teeth, the rectangle makes perfect A4 dimensions.

And since I didn't really know any rule regarding how big the teeth should be, I spent some time experimenting to find the right balance between the number of teeth and their width and the space they should have between each 2.

I planned to glue the plates together so I wanted to have as many teeth as possible to maximize the contact surface between each 2 plates, hence maximizing the amount of glue used to secure them more firmly. But the teeth shouldn't be very small as they will become more fragile, and cost a bit more when cutting (in my local FabLab, cutting cost is calculated by using the quantity of material used and the time spent by the machine while cutting/engraving).

I hopped back to the top plate to start making the holes for the banana terminals and the potentiometer.
We'll have a grand total of 32 holes including :

• 16 for the resistors' terminals (2 each)
• 3 for the power supply's terminals
• 3 for the potentiometer's terminals
• 1 for mounting the potentiometer
• 4 for the capacito's terminals (2 each)
• 5 for the amplifier IC

To keep the design as beatiful and as pleasing to the eye as possible, I wanted to have everything symetrical. So I divided the 8 resistors to be 4 on each side with a capacitor below each column. Placed the amplifier IC in the middle. Placed the power terminals in the top center, and the potentiometer in the bottom center.
I left enough separation between the different types of components' terminals and mounting holes so that I can create some frames to be engraved, to separate each component type afterwards.
It took some prototyping and thinking before getting to that layout. But eventually I got it right.

After the holes were in place, I designed the frames that would seperate each component type. I started off with a rectangle, and added some fillets to round the corners and make them more esthetically pleasing. And I then used the thin feature set to 1mm wide to engrave them 1mm deep into the top plate.
How deep I engrave them won't really matter. You just need to have the lines created on the top face to be able to export them when the files are ready to be cut. I just made them 1mm deep so that I can visualize them well in SolidWorks.

Discussing features

3 weeks ago, I went to my teacher to see the old model given by the ministry of education, and discuss the things that I should include in my new refreshed design.
We pulled out some of the old models :

As you can see, the entire model is built on a very low quality PCB, that was mounted on a very cheap and ugly looking electrical box.
It works fine but my teacher didn't like the appearance and the 2mm terminals.
We checked how many 4mm terminals we had, and sorted them by color to determine how many components to include.
We found that for every color (red, black, yellow, green, blue), we had 10 terminals + 6 but their colors were slightly off.
We started discussing the number of capacitors we should include include in the new design, and we initially agreed on having :

• The amplifier IC (still didn't agree on the specific chip)
• A 10K Potentiometer
• 2 100nF capacitors
• 3 1K resistors
• 2 2K resistors
• A 3K resistor
• A 5k resistor
• A 10K resistor
• 3 power terminals

For the teminals' colors, we decided to go with the same ones as on the old model. But to make the use od the colors more even, and to have as many of them as possible to spare for a second model, we decided to make the capacitors' plugs green, and the negative terminal of the potentiometer black.

And of course, the new model should be cleanly designed to be laser-cut and engraved on MDF wood.
And we decided that all of the components will be hidden inside of the model's enclosure, and have only the symbols engraved on the top face.