4- Final Steps: Designing and Manufacturing

Fixing the problems encountered in the first prototype, we decided to reduce the number of levels to two.

We modified the design of the connectors and slider joints too to increase robustness.

• Replaced 3D printed connectors with off the shelf metal corner brackets.

• New sliding joints made using wooden pieces sliding on metal shafts.

We modeled the final design in Solidworks including all the final details.

Solidworks Model

The lead screw is in the middle. It is connected to the motor at the bottom and the base support of each level.

Three separate levels of walls (upper two of them are rigidly connected) are highlighted in different colors.  

Cyan rods on the sides are the newly designed slides. We downloaded the Solidworks model for the metal corner bracket from Mcmaster and place it in our design to ensure accuracy.

To include autonomy in the folding and unfolding of the castle, we used the Arduino Uno board to control the motor speed , rotation direction and timing. It takes around 65 seconds to drive the whole system up or down.

Manufacturing

We spend a lot of time machining the whole system, the following are some key points of the manufacturing procedure.

Slider Joints

The improved design of the slider joints is based on the relative motion between a wooden piece and a shaft passing through it. We drilled a hole through the wooden block with a bit larger diameter than that of the shaft and placed metal bushings at the end. Hence, the only contact points of the shaft with wooden block were the bushings at the end. This ensured a smoother motion.

Minarets

The output links of the four bar mechanisms acted as the erecting minarets. Based on the link lengths obtained from the MATLAB calculations, we first tried to build the minarets using wooden cardboard. But, the dimensions were quite small and the wooden board was not strong enough. Hence we decide to switch to Acrylic. We laser cut the required links out of Acrylic board and made the revolute joints out of small metal shafts.

Lifting Mechanism

We 3D printed two unique shaped parts as the support of the walls to make the connection between the lead screw and the walls more robust.

We removed  threads of the lead screw after the designated height to generate the relative motion between the levels. After reaching the smoother part, the outer level stops while the inner level which is still moving on the threads continues to move up.

Engraving

To make the castles more artistic, we first painted the castles and then engrave it with the following patterns

And the final design then become much more pretty.