Antikythera Planetary Prediction Mechanism

The goal of the project is to reengineer and create a prototype of an ancient Greek device that was used to predict astronomical portions of know celestial entities based on the Jian-Liang Lin and Hong-Sen Yan design.

=Problem Definition=

Background
The Antikythera Device was the world’s earliest computer. This mechanism, found off the island of Antikythera in the late 1800’s, was dated around 100 BC. The goal of this device was to use gear ratios to predict the positions of the moon and planets at a given date.

A University of Idaho Graduate Student, Alex Olson, created a prototype of this device, but had several unexpected problems. One set of gears in the planetary part of the device interfere with the outer axles. One axle that should be stationary, rotates due to an unsuccessful press fit. The date spiral needs to be designed to show what date the planets are at what position. The goal of this project is to solve the problems in the prototype and bring the machine to working condition. This will go in the Dean’s office, and show some of the projects that the University of Idaho students are capable of making. And the whole device is novel, because this will be the first fully operational version of itself in the United States, and the third in the world.

This project will be a relatively cheap (under $400) for getting the device to work. It will be interesting in the Dean’s office, and will be informational for both what the ancient Greek’s were able to make, and also where the planets will be at a certain date.

Product Requirements

 * Schmit Offset couplings
 * Check if two discs works instead of three
 * Design in Solidworks
 * Prototype large size
 * Prototype actual size
 * Find new location for third axle
 * Secure axles on each side of couplings
 * Create out of brass (get Bill’s help)
 * Assemble couplings and device
 * Straighten offset axles
 * Check problem
 * Assembled wrong?
 * Material weakness?
 * Fix problem
 * Reassemble device
 * Find way to fix center axle
 * Glue?
 * Less permanent way?
 * Design spiral
 * Switch dates from Greek calendar to modern calendar
 * Design dial to turn gears
 * Design extending pointer
 * Find aesthetic design
 * Make overall width and height smaller
 * New material other than acrylic?
 * Have to do this after date spiral is designed
 * “form follows function”
 * Lunar phase gear
 * Can't use bevel because it wasn't invented yet

Action Items

 * Design Schmidt offset coupling in Solidworks – 6/18
 * Completed Team Contract– 6/18
 * Client Interview Questions/Strategy– 6/18
 * Draft Budget estimates for both Summer & Fall– 6/18
 * Prototype large size schmidt offset coupling– 6/18
 * Product Requirements Document – 6/25
 * Prototype actual size schmidt offset coupling – 6/25
 * Cut offset coupling out of brass – 6/25
 * disassemble device – 6/25
 * Order parts with Molly – 6/25
 * label/stamp gears – 6/25
 * Project Schedule – 7/2
 * find way to fix center axle – 7/2
 * assemble offset coupling– 7/2
 * reassemble device– 7/2
 * design dial to turn gears– 7/2
 * Polish/Clean up gears– 7/2
 * Portfolio, Initial Wikipage, Logbook – 7/9
 * remake offset shafts – 7/9
 * design extending pointer for dial – 7/9
 * Design Crown Gear – 7/16
 * Design Validation Plan – 7/16
 * lunar phase gear – 7/16
 * Concept Design Review – 7/16
 * Project Value Proposition – 7/23
 * switch dates on sprial to modern calendar – 7/23
 * Make overall width and height of device smaller – 7/30
 * find aesthetic desgin – 7/30
 * disassemble device – 7/30
 * reassemble device – 7/30
 * redesign Planet dial – 7/30
 * Snapshot Storyboard – 7/30
 * Portfolio, Wikipage, Team Member Citizenship, & Logbook – 8/6

=Design Considerations=

=Project Learning= Another large portion was attributed to parts manufacturing. Many of the designs being implemented were a proven concept and we reverse engineered them and downsized them to fit into the mechanism

Schmidt Offset Coupling
All of the offset couplings that can be purchased, use three discs to allow the axle to return to its original offset, but our project didn't require that, so our prototype was to determine if two discs would mess up the design.



Date Spiral Indicator Design
Several designs were thrown around when the dial was being designed. The first was a tube with a spring in it to apply a constant pressure on the dial indicator, but we decided to go with a simpler design. Both, however, use a spiral slot to keep the indicator in the correct spot in the dates.

Recreated Acrylic Plates
When Alex originally cut the acrylic plates, he used cutting fluid in the CNC which caused a chemical reaction with the acrylic and created small cracks radiating out from any of the holes. We re-cut them, this time without using the fluid and this kept them intact.

Aesthetic Plate Frame
To make the device look more aesthetic and less like a block of acrylic we pitched some new design ideas. One was to cut out more from the acrylic plates allowing more visibility. Another was to copy a skeleton clock idea using brass. But the main goal was that "form follows function". We would need to keep the holes for the support spacers and give them enough support to keep them from bending or breaking.

Fixed Shaft
Level two of the main shaft (down the center of the device) needed to be kept stationary. We tried to use epoxy, but that cracked. There wasn't enough surface area to keep it strong. So we designed a bearing (like many of the other ones on the gears) to keep in stationary.

Remanufacture Offset Shafts
The original offset shafts that Alex created were not machined totally square, meaning that the gears would spin at an angle and sometimes not even mesh at all. So we had to re-machine them to make sure the holes were drilled in exact parallel to the shaft.

Greek Calendar Recreation
The original greek calendar used on this device was a lunar calendar. This means that it goes by 12 lunar months instead of the 12 solar months we normally use. They are very close in length, but aren't completely the same. Over 19 years, the lunar calendar adds 7 months and this makes exactly 19 solar years. So 235 lunar months equal 228 solar months exactly.

Input Crown Gear
We needed an input gear to allow us to turn the device without using the dials with wouldn't be able to support the force. A crown gear was our solution for this problem.

=Final Design=

=Validation=



=Team Members=

=Additional Documentation=

12:00 – Re-asked Alex questions so that the professors knew what was going on
Scale down and implement offset couplings into mechanism

Will compensate for meshing of different gear ratios, as well as allowing for clearance of rotating gears

Rebuild some offset shafts to better align gears for a cleaner mesh

Rebuild acrylic frames to hold new offset couplings, possibly implement aesthetic design into acrylic

Create a new modern interpretation of the Greek calendar with a pointer and slider implementation

Attendees:
Beyerlein Odom Sarah Alex Rakan Mshari Shane

Notes:
-	Levi was taking FE

12:30 – Develop product requirements
Prototypes began

Move device to meteorology lab

Show validation of design/changes

Implement into 3-D model

Use or modify old frame plates to show fitment

Create simple quick prototypes

Attendees:
Mshari Rakan Shane Levi Sarah Alex Beyerlein

Notes:
-	Don’t completely loosen the lantern gears set screws

-	Third offset only needs to be supported on opposite end of shaft

-	Input gear will mesh with gear #32

-	Move/relocate shaft for gears #12 and #28

-	Build press fit hub for stationary shaft? Use glue?

12:10 - disscuss work schedule
Verify if we are on track, and what tasks have been completed

12:30 – decided week’s work plan:
Monday 7/2: Rakan and Mshari began design work on calendar dial mechanism

Tuesday 7/3: Ordered Parts will arrive; assemble offset couplings

Thursday 7/5: remake acrylic plates; rebuild offset shafts

Friday 7/6: crass shaft arrives; reassemble mechanism or rebuild plates

Attendees:
Mshari Rakan Shane Levi Sarah Alex Swenson

Post meeting notes:
-	Find system for tracking revisions in files

-	Alex will be gone by 7/30

12:00 – run through schedule and where we are in the tasks
working on machining plates

working on spiral design

12:05 – how to cut the offset axle
do we need set screws?

12:07 - spiral date indicator
two slots?

Brass slider instead of acrylic

Keep it from jamming

12:10 – spiral design
sprials are the same size

marks show where eclipses are

12:15 – Machining plates
make sure they are in the right place

Attendees:
Mshari Rakan Shane Levi Sarah Alex Swenson

Notes:
-	Strikethrough for finished tasks on top of color

-	Move design review to Wednesday at noon

12:20 - Slides Review: (Suggestions)
•	 Address: Crown Gear, offset shaft

•	Number of Slides

•	Prospective for offset, coupling placement.

•	Bring in Mechanism to presentation.

•	Slides > Show DVP

•	Consider slider having on open end.

•	The presentation will be in EP 209.

•	Epoxy in Pins to offset couplings.

•	Restrain shafts from separating coupling.

•	Change the team name.

•	Fix “Project Learning” >> “ Project Management”

•	Look into “Schmitt coupling” name.

•	Coupling animation > Clear front disk.

•	Back plate >> Extra holes.

•	Add table for equations on offset.

•	Include remade calendar from Alex’s thesis.

•	Point Dial Pins arc.

•	 Add slide for QUESTIONS.

•	Add animations to Questions slide.

Attendees:
Mshari Rakan Levi Alex Sarah Swenson

Notes:
-	Presentation at 12:00 pm. EP 209

-	Tell Bill about our presentation and the location.

-	Shane was at a wedding so was not able to attend

11:30 – Project Value Proposition evaluation
•	First couple paragraphs are good

•	shorten

11:35 – Spiral Date reset after 19 years
•	figure out design requirements

Attendees:
Mshari Rakan Levi Shane Sarah Swenson

Notes:
-	email alex about way to reset date indicator

-	have better meeting agenda

-	“always go back to the requirements” – Swenson