11/6/2025 - Made the first version of the board design

4.11.25
I spent about 45 minutes researching possible parts for the project, including stepper motors, electromagnets and main boards. I was initially thinking about using an Arduino board, but I realized that the GUI app that I want to build is very complicated to write in C, so I switched to a Raspberry Pi.

5.11.25
I designed the top of the board in Fusion 360. It was to big to 3d print (on my own printer) in one piece, so I had to break it up into 4 smaller ones. I made a cross-shaped beam with holes to hold them together. That was also too big, so it had to be spit up as well. I chose to connect it all in the middle, but I have some concerns with it being too thin. I hope it will hold up.

Here is the bottom side of the board, without the beam. The top side looks like any other chess board.

This is the beam.

11/10/2025 - Tweaked board and created XY-joint

6.11.2025
Instead of pins coming out the beam to hold the board together, I decided to use some stainless steel pins that connect the beam with the pieces and made the necessary adjustments. This took about 30 minutes.

9.11.2025
Added screw holes on the side of the board for attachment to the case. I used M3 screws. This didn't take a lot of time, but I also did some research on the core xy cartesian system, which I plan on using (about 1 hour in total)

10.11.2025
Did some more research on a possible electromagnet, steel rods for the y-axis and linear guiderail for the x-axis and made a xy-joint: a piece which contains a linear bearing that runs along the y-axis and attaches to the guiderail of the x-axis.
I decided to get rid of the bead that holds the board together and just use those steel pins to join the pieces directly, but haven't made the changes.

Here is the modified board:

and the xy-joint (it's still and early prototype, I have to split it in two and add screw holes):

11/14/2025 - Worked on Core XY System

10.11.2025
I added screw holes to the xy joint. I then had to move them on the other side, because on the top of the joint I will have to mount the idler pulleys. I also gave up on the hexagonal shape, because it was too hard to 3d print.

14.11.2025
I started work on the part that actually moves the chess pieces around. I designed the guiderail carriage and thought of an idea of how to move a permanent magnet up and down using a servomotor. I started the sketch for the mechanism.

Here is the xy joint seen from below:

Here is the sketch for the carriage. I am thinking of a mechanism that uses a disc with a pin to pull a rod that has the magnet at the end up and down.

And this is the core XY system so far:

11/15/2025 - Designed the magnet mechanism

15.11.2025
I finished the design of the mechanism I started yesterday. As I said, I went for a piece that holds the magnet and goes up and down, guided by the holes in a bigger piece. It is moved by a disc with a pin.
I 3d printed what I thought was a working version, but, apparently, some tolerances and dimensions had been messed up when I made some edits. I fixed them and I'm going to print the new version tomorrow.

Here is the big piece with the magnet-holding one in it:

An this is the wheel with the pin. You can see how it interacts with the one with the magnet.

11/24/2025 - Worked on the carriage

16.11.2025
I made some adjustments and printed a version that, with a bit of sanding, was great. I had some concerns about the pin breaking, but that didn't happen, now I have to see if a magnet of the chosen size will be strong enough.

During the week, I added screw holes to mount the mechanism to the guiderail carriage. I had some trouble because the disc was in the way of the screws and I had to use headless screws for that part. I also struggled with the dimensions of the servomotor and didn't make much progress because of it.

24.11.2025
I found a 3d model of the servomotor that allowed me to design the mounting. The problem is that it partly obstructs the hole where the wheel is inserted, So I had to make a bit of space and shrink the wheel. I hope it'll fit.

Here is the mounting without the motor:

And here it is with it:

12/4/2025 - Added pulleys and belt attachment holes

29.11.2025
I made the first sketches for the core xy system: I placed the pulleys.

30.11.2025
I modeled the pulleys according the the ones I decided on using. I'm using the same ones usually found in 3d printers. I also searched for steel pins to fixate the pulleys and modeled holes for the belts to attach to the carriage. I was inspired by my Prusa 3d printer that has something similar.

3.12.2025
I positioned the pulleys on two levels to allow the two belts to work independently.

Here you can see the holes for the belt:

And here is the whole system, with the pulleys spread on two levels:

12/21/2025 - Created mount for stepper motors

Over the past week I've had some challenges with the motors. I realized they were too big to fit in the vertical space that I had arbitrarily chosen. This was not all that bad, as I could just make the whole board taller, but they also didn't fit sideways: the carriage would have hit them when going to the corner and the belt would have had some weird angles. I then thought of methods to make them fit. The idea I came up with was to make the x-axis longer, thus creating space for lowering the pulleys. In my head, this would allow me to fit a slimmer motor upside down, over the pulleys. I did not have the space and these motors were much more powerful and required move power, which I didn't really have any idea how to supply.

I began to worry that I might not be able to work this out, but, after scrapping the slim motor idea, I realized that rotating my current motor would solve the carriage problem. I would just have to accept the board is now about 6 cm tall. I thought this was my only option, so I went for it.

I created the mounts for the motors, as well as what I hope to be a belt tensioning system that uses screws to move the mount and the motor.

Here is the left mount:

And here is the right one:

12/26/2025 - Redesigned board and created ejecting mechanism

Since the last entry, I've tweaked the board design. I've removed the connecting beam and the 4 pieces now directly connect using steel pins. I've also extended the lateral walls and added screw holes. After that, I created the mechanism for ejecting pieces off the board, after they are taken by the other player. I chose a special square and I added a hinge to allow it to rotate about 20 degrees in order for the chess piece to slide off the table. I initially had two ideas that are hard to describe, but I ended up adding some prisms to both the special square and the magnet carriage that allow the carriage to rotate the square.

Here is the special square seen from underneath. You can see the prism:

Here is the ramp I added for the sliding piece. You can also see the prism added to the carriage:

And here is the whole board:

1/17/2026 - Created schematic for PCB

27.12-29.12.2025
Beside moving the pieces, I want the board to also detect where the pieces are on the table, so I can also make my moves. For this, I am making a PCB that will go directly under the pieces. It will have hall sensors for every piece, thus being able to detect their presence.
So I started to design the schematic. My dad helped my throughout the process. I decided to use a Raspberry Pi Zero for the board, because the other ones were too big. Because the board requires a 8x8 matrix, we used a I2C expander to reduce the number of pins needed. We also added another chip that provides more current for the sensors. I also thought of integrating connectors for the stepper motors and servomotor that connect to the Raspberry Pi. For connecting the stepper motors, we had to use an 8-bit buffer for logic level change. (conversion from 3V supplied by the pi to 5V required by the motors).

Because the board is split into 4, the PCB had to be spit as well. Because of this, at the end, we put some thought into the placement of connectors that connect the 8x8 matrix to the Pi. We positioned them so that 3 of the 4 PCBs are identical, to save on cost. The 4th one has all the chips and motor connectors on it, as well as the cutout for the piece eject system.

Here is the schematic, broken into 3 pages:

This is for the 3 identical PCBs

This is the special one

And this page is dedicated to the Pi and the connectors for the motors

1/18/2026 - Started PCB

29.12.2025
I assigned all of the footprints to all of the parts. Some of them were harder to find. I also searched and settled on some pulleys. I updated the BOM to include them and started designing the PCB. I made a simple box and arranged the sensors according to the dimensions of the board.

Here it is:

1/26/2026 - Finished the PCB layout

17.01-18.01.2025
I arranged all of the components on the PCB and settled on a design that has some extensions that connect with neighboring PCBs. On the special PCB, I crammed the stepper motor drivers and the Raspberry Pi connectors. I had to overlap them to make them fit, and I will buy a longer header for the Pi.
Before doing the routing, I'm going to continue designing in Fusion.

Here is the normal PCB:

And here is the special one:

1/28/2026 - Starting to wrap up

Over the past week, I've been busy fixing little details and putting the project together. I've made spaces for the components on the PCB, I've searched and imported 3d models for the connectors, Raspberry Pi and drivers. I've also painstakingly extruded all the holes for screws and nuts that will keep the whole thing together and rearranged the pins that connect the 4 quarters of the board.

This is how it looks now:

1/30/2026 - Adding the finishing touches

29.01.2026
I added the last touches to finish the project: added screw holes in the PCB, created pins that connect the two slices of the board. The PCB goes in between them. I also created a support and a guiding piece for the servomotor cable and added holes for the pi's ports. At the end, I routed the PCB, updated the BOM and gathered all the files for submitting the project.

Here's the finished board:

and the PCBs:

2/4/2026 - Fixed PCB holes

04.02.2026
I realized that the hole I had made in the PCB were off by almost a millimeter, so I fixed them. I also remembered that I forgot to add holes for the pins connecting the two plastic pieces of the board "sandwich".

You can see the new holes around the middle of the PCB. The tileable one has more holes, because they always have to be towards the center of the board.