Buying List
| Item | Vendor | Price | Unit |
| Arduino MEGA 2560 | Arduino | $50 | 1 |
| Encoder (1250 CPR) | US Digital | $75 | 1 |
| Encoder (500 CPR) | US Digital | $65 | 1 |
| Motor (0-COPAL50-6) | Robot MarketPlace | $25 | 1 |
| Motor Controller (0-PL1372) | Robot MarketPlace | $35 | 1 |
| Large Pulley (1375K53) | McMaster | $15 | 1 |
| Small Pulley (1375K21) | McMaster | $10 | 1 |
| Belt (1679K84) | McMaster | $1 | 1 |
| Battery (9V) | convenient sotre | $4 | 1 |
| Mechanical parts | self made | - | - |
| Total cost: approximately $280 | |||
Machenical Structure
The mechanical parts was made by a 3D printer. The Autodesk Inventer design files are available in DOWNLOAD section. I and my MakerBot 3D printer:
This photo was taken when I just finished assembling the 3D printer--MakerBot Thing-O-Matic. It took me 26 hours continuously working on the assembly. (April 1st, 2012)
Pendulum Base
Part1.ipt and Part2.ipt construct the pendulum base. The 500 CPR encoder is fixed in the left, and the motor is under the large pulley.
Arm
Part3.ipt and Part4.ipt construct the arm. A copper rod is in between Part3 and Part4 to make the arm more rigid.
Pendulum
Drill a hole to the pendulum, and connect to the encoder shaft directly.
Electrical Diagram
