Wei Xun He

How to Make this Real?

How to open it?

For my last works-like model, I simplified the Sarcaphagus as a shoebox and designed a motorized arm that rotates to open the lid... This time, it's time get real.

When designing the mechanism to open the lid, the most important question was, should this be external or internal to the Sarcaphagus? Opening a lid externally is the most natural solution. It's what we do everyday. We can model an arm's pulling action with a pulley system that applied force upwards from the lip of the lid, done. Problem is, does that look realistic? How much will these irrelevant pulleys and chains dangling from the roof detract from the experience? Our theme is Egypt and the goal is to awaken the mystical Pharaoh, so the lid NEEDS to open more magically. The other option is to open it internally. With this method, the opening mechanism is hidden for the most part, but from an engineering standpoint, this is more challenging and pricey. After a team discussion, we decided to move forward with designing the internal mechanism in the interest of maintaining the immersive atmosphere.

What to prioritize?

In the world of getting things done under time constraint, prioritization is key. Now that we have 2 weeks left until final presentation, I asked myself, what challenges of the Sarcaphagus do we need to solve right now in order to convey that 5WITS should totally pursue this idea? This helped me wrestle with the design team.

In the Egyptian world, Sarcaphagus are very standardized. The forms of these coffins outline a real human, making it very realistic. However, constructing curved walls would take a lot of effort and time. More importantly, creating curved walls doesn't tell us anything new... especially since the Egyptians already did this centuries ago! As a result, we decided to simplify the shape into just a rectangular box and focus on demonstrating that we can create the mystic opening experience.

For future, if we have more time, here's how I would build the realistic model. The Egyptians back then probably found huge logs and carved out of it, so that's one option. Or we can leverage rapid prototyping tools like router to cut out a smooth profile on wood planks sourced from HomeDepot. From research, the thickest planks are 3/4", so to construct a realistic and structural coffin, I would glue two pieces of 3/4" together and then route it to the desired profile, which can be designed with a 3D modeling software like Solidworks.

Digital Rendering

This is What I Hope It Looks Like in Two Weeks!

Real Prototyping Plan

Here's How I Plan to Make This Happen

First, I want to make a box that is structural. Since I have to upgrade from the cardboard I used last time, I need to source more appropriate materials and think up new construction method. I found 3/4" thick plywood from HomeDepot, which I plan to cut to size and screw together. Then I found a 30" long hinge that allows me to pivot the lid and one of the long side of the box. I also plan to engrave the walls with hieroglyphics using the laser cutter.

Second, I want to electronically actuate the lid to open and close it at will. I researched multiple technologies, and finally narrowed it down to a linear sliding actuator. This provides the linear motion I need to push the lid open, keeping the action minimal and internal. Then I modeled the geometry and forces to find out how the angle of the lid varied with the force applied, which I did in excel. After modeling the forces in the system, I found that I need an actuator to support at least 743N of force, which equates to 166.5lb of weight, helping me choose an actuator that supports up to 180lb. In addition, there is an engineering consideration with the rotation of the lid. In order to maximize ability to see inside the coffin, we want to maximize the angle, but as the lid rotates close to 90 degree, it may potentially flip the other way due to momentum or if the player was to even apply a tiny force. If this happens, then we lose control and the room will go down because it can't reset anymore. I plan to prevent this situation both in hardware and software, by designing a mechanical stopping mechanism, like a servo motor, and telling code to stop after 85 degrees.

Third, I want to complete the experience. This involved acquiring the fan and speakers. When I made my works like model, I had only one speaker and one fan activated inside the Sarcaphagus, and the effect wasn't as immersive as I wanted. It was difficult to feel the wind and the sound was hard to hear. As a result, I plan to fit four box fans and a pair of surround sound speakers inside the Sarcaphagus. I also designed meshes of air pockets on all sides for sound and wind to travel, which I think can exagerate the effect.

Once everything is put together, I plan to create the 3D contour of the lid using Autodesk 123D Make which slices the model into 2D sheets that I can lasercut using a light material like cardboard. I will then sand the combined product and spray paint to make it look realistic.

To learn more about how the Sarcaphagus will communicate with each of the wall, please check out the electrical and software.

Bill of Material

Component	Function	Key Specification	Source
Plywood 1	Lid and bottom	3/4 in. x 2 ft. x 8 ft.; 36lb	HomeDepot
Plywood 2	Short walls	3/4 in. x 2 ft. x 4 ft	HomeDepot
Plywood 3	Long walls	3/4 in. x 4 ft. x 8 ft.	HomeDepot
Hinge	Pivots lid	1-1/16 in. x 30 in	HomeDepot
Linear Actuator	Lift lid	12" Stroke 115 lb (heavy duty)	ServoCity
Fan	Immersive experience	20-Inch, 3 speeds	Amazon
Speakers	Immersive experience	Surround sound	Amazon
Adafruit Feather	Microcontroller	Bluetooth capability	Adafruit
Smart Outlet	Listens for signal from puzzle when solved to activate electronic outputs	Strong RF signal	EtekCity

Hatshepsut's Journey: Sarcophagus Mechanical Design