CURVED RAIL

The next major component we tackled was the curved rail.

Due to its large size and the need for durability, we chose to laser-cut it from plywood/acrylic instead of 3D printing it.

Dimensions:

• Outer Diameter (OD): 560 mm

• Inner Diameter (ID): 450 mm

The rail is composed of four layers, all secured together with M5 screws:

1. Two outer planks — 5 mm thickness each

2. Inner plank — 10 mm thick, this is the guide surface where the cart wheels will slide

3. External gear layer — 5 mm thick, this gear will be driven by the cart to move along the curve

   • The design of this driving system is inspired by this mechanism: 

Rail Support: Feet and Top Part

To hold the rail we designed those two piece :

Rail feet

The rail "Feet" is a very important part, it house the chessboard stepper motor, the cart and the orb limit switch.

It connects to the rail using a m8 bolt

Limit switch

As we're using stepper motors to move the cart and chessboard, we should be able to achieve a high degree of accuracy when moving to a position, but one problem with stepper motors is that, being an open-loop system, they wouldn't know, for example, where they are at start-up.

To solve this problem, we used limit switches in the path of each motor so that they could have a base (reference) position.

Here's the limit switch for the chessboard and the cart :

CHESSBOARD A 3D printed piece is fixed to the stepper shaft.

CART

Rail Top

The Top part help to complete the assembly

It also connects to the rail using a m8 bolt

Here is the final assembly showing the curved rail, feet and top parts, stepper motor, the spherical chessboard, and the chess pieces: