There are three primary mechanical subsystems within our project: the gantry system, the physical chess board box (including an elevated camera mount), and the chess pieces.

The Gantry

The gantry is the most complex of the mechanical subsystems. It's responsible for moving the electromagnet to anywhere in a 2D plane. For our first sprint, we bought cheaper linear rails and sliders from Amazon. After testing these rails in 2D, we determined that they wouldn't have enough precision for our purpose and had to exchange them for slightly more expensive rails and sliders. Two of our rails are mounted parallel to each other directly to our base, and the third spans the distance between them, mounted to the stationary axes' sliders. We also custom-built mounts for our pulley and motor systems, of which we had two: one that runs parallel to the moving rail (along what we call the x axis) and one that attaches directly to the moving rail at a 90° angle to pull the gantry along what we call the y axis. We also created and 3D printed a mount for the electromagnet that could be easily adjusted for height. The gantry system in CAD is shown in the photos above.

The Physical Chessboard

Our physical chess board box is 26 inches square and four inches tall. Except for the top, it is made of ¼ inch MDF. We encountered issues while trying to obtain stock that was big enough to fit the entire 26 by 26 inch square, and ended up cutting the base in half and putting a half-lap joint in the middle to secure it and reinforce the glue. A picture of the box is shown below. The top of the box, which makes up the actual chess board, is made of three layers: ⅛ inch hardboard, printed poster paper, and 1/16 inch clear acrylic. We spray painted the entire board black except for the poster paper and clear acrylic, and lined the board with LEDs. We have four buttons, two on top of the board and two on one side. The camera is mounted about a foot and a half above the top of the board on a custom mount made of lasercut plywood.

Chess Pieces

We also have two full sets of chess pieces, which are 3D printed from PLA. We began with designs from user BigBadBison's Spiral Chess Set on Thingiverse (licensed under CC BY-NC, then modified them in Meshmixer to achieve the correct scale and add indentations for magnets. We made them 0.9in wide (except for pawns, which are 0.75in) so that they will have room to move through our 2in squares and have enough space left over for a knight to move between squares. After printing, we glued the magnets on the bottom, printed out unique Apriltags on cardstock, and glued those to the top of each piece.