11/2/2025 3 PM - Discussing features

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.

11/2/2025 4 PM - 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.

11/6/2025 - 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 !

1/6/2026 - 3D Design Pt. 3 ; Patterns to be engraved

I had a lot of exams so I had to take a break.

I focused on another project during the holidays, but now since my teacher needs it soon to teach with it, I have to get back to work.

For engraving, I wanted to put normalized symbols for each component + some text.
First, I started by making the enclosed shapes that weren't going to the holes and cut them 1mm using a 1mm thin feature.

I drew closed shapes first because I encountered some errors when doing everything in the same sketch where there are the branches that go to the holes. Solidworks couldn't execute the cut extrude feature.

At first, I couldn't really understand the error message. So I deleted everything and started drawing and cutting every group of entities.

Everytime I add a group of rectangles, lines... I re-execute the feature to see where the errors begin.
Errors started showing up when I added the lines. Thin features were conflicting with eachothers and with the circles.

Next, I made the branches that went to the holes, and actually left a small gap before reaching the holes.

You see, if I made them directly go the holes, they would show up in the DXF file as one entity, and they would both be engraved together or cut together. I wanted the holes to be cut and the branches to be engraved, so I left a small gap to separate them.

And in the process of doing that, I modified the holes positions' to get something more pleasing to the eye.

Now, what's left for next time is adding the text.

1/7/2026 3 PM - 3D Design Pt. 4 ; Text

As I said last time, now it's time for making the text that'll be engraved.

I first tried to write the text without anything else. Just write the text and then place it.
I thought that it will be pretty easy to do, since I thought that it worked the same way as Microsoft Word. Drag and place, and Solidworks will help you position it.

Solidworks didn't have those snap lines to snap the text, so I thought that I'll use constraints. But the text showed up as only a text, not like Word with a text box that has dots to help you position your text.

After watching some videos on YouTube, it turned out that I can place a constuction line, write a text onto it, and then I can choose the arrangement... relative to the line's position and center. So I did just that !

I wrote the text and positioned it, and then I got back to adjust the text size and font.

I tried placing the resistors labels on each side so that each series would make some sense when you look at each column.

At this point, it was really a matter of how it looks, text should be apart from eachother, and big enough to be read.

So I spent some time prototyping to get things looking right.

And finally, of course, I had to write my name, and my teacher's. I hid them in the picture below for obvious reasons.

1/7/2026 5 PM - 3D Design Pt. 5 ; A requested modification

After showing what I've done to my electronic engineering teacher, he liked it, and asked me to add 2 resistors.

And to see how the thing will look like before cutting it, he asked me to put the terminals inside of the assembly.

So I started by adding the 2 resistors like he said. To keep everything symetrical, I put one on each side.

After doing that, I proceeded by adding the terminals inside of the assembly like he asked.

I downloaded a model online, and made a copy with every single color that I'll have in the final design just like real life.

Unfortunately, the models I found online were very detailed. The threads on the models were pretty heavy on my computer (8GB of ram :/), especially since they were 35 terminals.

They made SolidWorks run really slow, and the terminals kept disappearing on they own. So it made making the constraints very difficult for me to fix the components in place, but I ended up by getting it right.

Taking this shortcut was pretty difficult as the terminals kept disappearing :) But fortunately, this is the last step of the 3D Design.

What is left now is laser-cutting and assembling everything together !

1/10/2026 - Laser Cutting

In this journal, I won't log the time the model took on the machine. Just the things I had to do to prepare it for cutting.

First of all, I had to prepare the files for cutting. For all of the parts, it was as easy as a right click on the front plane of each part, and export as DXF.

But for the top plate, I had to select each loop, line... so that they would appear on the engravings.
After that, I had to send the files to the guy in charge of the machines, and tell him what to do as cutting, and what to engrave.

But when he was calculating the cost, it turned out that the wood was 2.7mm thick instead of 3mm.
I thought that it was a really big deal, and tried fixing it.

But as soon as I started fixing the dimensions, errors in the assembly started popping up violently.

I insisted on trying to fix it since 0.3mm was 10% of the dimensions. But when I couldn't realiably fix them, I figured out that the machine is very dirty, and the 0.3mm can really fit into the tolerence of the machine at that state.

So I sent the model for cutting and engraving.

The first result was pretty underwhelming.

Even tho I really tried to correct for the teeth spacing tolerence, there was still some large play.
And when I thought that the engraving looked clean and dark, when I got the model out of the machine, the engraving turned out to be very light.

Also the cut's were not clean. The laser power was set a bit too low or the speed was a bit too high.
When directly under the sun or under a light source, they become a bit difficult to read.

But fortunately, those 0.3mm were almost fully eaten by the machine's tolerance, and the borders came out almost flush.

I asked the guy to do it again.

He tried re-engraving on the first model, but it came a bit offset and still light since he used the same laser power to avoid the engravings reaching through the wood.

So I asked him to do it all over again, just the top plate.

Here is how the box turned out :

1/16/2026 - Back to 3D Design Pt.6 ; A requested change.

After taking the parts cut to my teacher, I realized some very stupid mistakes.

When making the model in Solidworks, I didn't really think about the students' behavior.

What my teacher mentioned, is that the model is too fragile.

Students tend to use this type of model very violently.

They pull out multiple wires at once instead of pulling them one by one...

The 3mm top plate flexes a lot, and with the whole thing held together with glue, it won't last 10mn.

So he brought me a wood box and asked me to edit the design so that the top plate mounts with screws.

So the only thing I had to do is to modify and cut again is the top plate.

So I hopped on Solidworks, and made a copy of the project, and started editing the top plate.

I first took the length and width measurements of the box and entered them in Solidworks.

I found some 4.8mm screws in a hardware store close to my house, that have those cylinder heads with a hex pattern inside. I really like those screws.

So I put 4 holes, one on each corner, in the center of the corner fillets of the frames so that everyting looks good.

Also after adding the holes, I added a small boss extrude function to separate them from the frames that will be engraved, so that they show up as separate entities in the DXF.

And one thing my teacher told me about, that could have ruined the design is to measure the wall thickness of the wood box he gave me, to space the terminal holes enough to leave room to place and screw them.

Here is how it turned out :

I made a DXF file, and I made sure to carefully select all of the contours, and sent it for cutting and engraving.

1/18/2026 - Back to 3D Design Pt.7 ; Stupid error

My dad went to pick up the latest file that I sent for cutting, after adapting it to go with the wooden box my teacher gave me.

He sent me this picture, and it looks really amazing.

I went back home after school really excited I was finally going to start working on it.

The first thing I did, was to place it on top of the box to see if it fits nicely.

And surprise, surprise, it doesn't :/

I don't know how, the holes were not spaced far enough from the side edges. Now, the side terminals can't be inserted in place.

There could be 2 possibilities for how this happened :

• I used center distance instead of minimum distance in Solidworks while measuring
• I remember spamming Ctrl + Z to cancel a design attempt, but I also remember saving and re-opening the document before making that attempt, so the spacing should not be rolled back.

I initially wanted to use the milling machine to eat some of the box edges to allow for terminal insertion. And with that idea in mind, I screwed in all of the terminals outside of the box, to see how this would turn out :

I immediately went to call my mechanics teacher for a solution.
He told my electric engineering teacher about this, and he asked me to do it again.
At first, I didn't want to, since this already started to cost him quite a bit of money, but he insisted.

So I hopped back to Solidworks to fix this issue.

I started by spacing the holes. This resulted in each pair of columns being closer to eachother, so I had to adjust the symbols between them.

Then I remembered that the screw holes came slightly offset from where I want them to be, and in that position they could crack the wood.

So I redimensioned the frames so that the screw holes come exactly in the middle of the box edge walls.

The design turned out looking a bit blank, especially looking at the side frames for the resistors since the holes came closer to the center. So I spent some time trying to improve it without messing with functional components, but this is the maximum I could do :

Again, I exported the file as DXF and e-mailed it for cutting. And hopefully, this should be the last iteration !

1/21/2026 - Assembly Pt.1

As today is a stormy day, and school was cancelled, I took the opportunity to go to my local FabLab to pick up the model I sent previously for cutting and engraving.

Looks good again, and as soon as I got home, I rushed to check if it fits correctly.
And it does ! The sides are flush with the box, and there is more than enough room to fit in the banana terminals.

So with that excitement, I tidied up my desk, went for lunch, drank A LOT of coffee, and got to work.

I first started by unscrewing everything from the old model, and screwing it back to the new one.
I screwed them in a way that would make the terminal plugs have concentric holes, so that I can lay the resistors between them for soldering.

After that, I got my cordless drill to try to make the screw holes and threads.

I know that wood screws should drill the threads by themselves, but the wood that the box was made out of was really thin and very rigid. And the screws were less than 6.5mm away from each side. So the wood was very prone to cracking, and I can't afford that.

So I bought a 4mm wood drilling bit, as the screw is 4.8mm in diameter, and drilled a hole for each screw.

This will get some material out of the wood, so that the screw doesn't push it apart and crack the wood.
Then, I carefully inserted the screws and turned them slowly until they reached the bottom, or the nail for 2 of them.

I ended up cracking one side, but it wasn't too bad.

And since there are nails blocking 2 screws, I will have to take the screws to my high school to cut them, as I couldn't do that by myself. I tried with pliers, a saw, but couldn't.
At school, we do have those heavy things that can help hold the screw in place for cutting.

Anyways, with that sorted out, it was now time to start assembling the components.
I borrowed my friend's soldering iron, as I am waiting for my new one to be delivered, and started to solder.

I started with some simple ones, which are the 1KOhm resistors.

I layd them flat between the 2 terminal holes, and tried soldering them normally.

It was kinda hard to get the first 2 ones right since I didn't want to overheat the terminals as they are plastic and expensive, and it was basically soldering metal to metal, which is very tricky.

Eventually, I got them right. But I then remembered that I had some flux laying around, which can help me solder easier.

For the next 1KOhm, 5KOhm, and 10KOhm resistors, I placed some flux on the terminal plugs, heated the plugs, and placed the solder wire just above the hole and resistor leg, and it made soldering quite easier, tho it was still tricky.

Now came the 2 and 3 KOhm resistors.

For these, my teacher gave me 1KOhms resistors to put in series.

I didn't have helping hands to hold the resistors, so I tried a pretty smart method.

I cut a small perf board, placed the resistors in a way that 2 consecutive resistos would share one hole, and soldered them together there. This made it very easy to solder them together, as solder adheres very well to the perf board pads.

I then repeated the same process above to solder the resistor assemblies to the terminal plugs.

I then proceeded with the potentiometer. Unfortunately, the potentiometer my teacher gave me had a threaded part thinner than the plate's thickness. So I had to swap it out with one of mine. (Spoiler alert, this didn't go well).

I didn't have some thin wire laying around, but I thought that it won't really matter with a thicker wire.

I soldered the wires directly on the terminal plugs, as well as on the potentiometer pins.

Unfortunately, in the process, I melted some low quality terminals out of place, but tried to get them ligned up back properly using multimeter cables.

I wanted to go on with the capacitors, but the ones my teacher gave me have very short legs, that can't be spread between 2 terminal plugs.
And by that time, caffeine, as well as the solder fumes and accumulated fatigue, started to mess with me.

The coffee I drank was so concentrated that my hands started vibrating and became very stiff to control, so I knew I had to stop.

But before doing that, I wanted to make sure that everything was done correctly. So I pulled out a multimeter and started taking measurements.

The resistors work just fine, as expected. But the potentiometer though, didn't pass any tiny bit of current.
The multimeter didn't want to show any readings, so I figured that it might be just broken.

I called my teacher and asked him to try to look for a potentiometer and some capacitors with longer legs so that I can finish working on this model another time. We'll see if he finds them !

1/30/2026 - Assembly Pt.2 ; Project done !

Today, I just finished this project.

My teacher gave me some capacitors with longer legs like I asked, and a new 10KOhm capacitor.

I started off by soldering the capacitors. I spread the legs between 2 terminals, and used flux just like last time to solder them.

It was just as difficult as soldering the resistors before.

Then I proceeded by desoldering and removing the old potentiometer, and soldering the new one.

This time, I bought thin wire for soldering. The thick ones I used before were very bulky and difficult to solder, and using them to solder the IC will be a real pain.

There is a "trick" my friend told me about, and it is to put the soldering iron in the flux for a little while before soldering. When I tried this, results were a bit mixed.

And by this point, I got a bit dizzy. The fumes from burning the flux felt very toxic, and by this point, my head started to hurt and there was a strange feeling in my throat.

I decided to take a break and go outside for a moment to breathe in fresh air.

And this also convinced me that the first thing I'll be getting from the shop is a fumes extractor XD

And to make things worse, I had opened the window in this cold weather, and it didn't really help with fumes.

Be careful when soldering, and try to avoid inhaling the fumes coming from it, as they tend to be extremely toxic.

Anyways, after taking the break, I went on to solder the last component : the amplifier IC

I didn't have a diagram, and the IC had 8 pins while I only needed to use 5 of them.

I hopped on google and found this diagram, which used the same triangle diagram as the one I engraved.

So I cut a small piece of a perf board, 5 ~10cm wire pieces, and started soldering.

I placed the wires first on the perf board, inserting them from the side with no solder pads.

I then placed the IC in a way that an IC pin and a wire will go in the same hole, for each connection, so that I can solder them on the pads, which will help me join the wires and the IC pins, just like I did before with the resistors.

And with that, the project is almost complete.

All that's left is cutting 2 screws so that I can insert them without hitting the box nails.

I used a mini angle grinder to do that, and it was my first time using it.

At first I got really scared that the sparks would burn my clothes, but my teacher cut the first screw with so much confidence, and it looked very cool, so I cut the second screw, and it was really cool !

That's it, the project is done !