http://www.instructables.com/i...

This robot arm is made almost entirely of 3D printed parts that snap together. It has three servo-controlled joints, plus a rotating base and gripper. The arm is controlled by a series of buttons that connect to an Arduino Uno hidden in the base. A simple circuit makes connecting the servos and buttons to the Arduino easy and makes set-up and assembly very quick.

• Arduino Uno - RadioShack 276 128
• Standard servos (4x) - RadioShack 273 766
• Micro servos (2x) - RadioShack 273 765
• Momentary push buttons (8x) – RadioShack 275 1566
• On/off switch - RadioShack 55050508 (web only)
• Potentiometer and knob (specific resistance doesn't matter) - RadioShack 271 215 and RadioShack 274 416
• Green LED - RadioShack 276 022
• Printed circuit board - RadioShack 276 149
• 10K Ohm resistor (8x) - RadioShack 271 1335
• 220 Ohm resistor - RadioShack 271 1111
• Various wires and connectors
• Nuts and bolts (16x 8-32, 1/2” long)
• Afinia 3D printer - RadioShack 277 181
• 1kg roll of PLA filament - RadioShack 277 163
• power supply, capable of 2A (I used a standard bench supply for prototyping, so something like RadioShack 550 57676 (web only) or RadioShack 22 507 should work although you will need to regulate the voltage before sending it to the Arduino and servos)

The arm is about 20 inches long, so it takes a lot of time and material to print. The parts are sized to fit on the bed of the Afinia H479 printer, and some can be printed together on the same platform to save time. I used a resolution of 0.25mm and hollow fill for all the parts (other settings were set to the defaults). In addition, I found that I needed to use a raft to both help the part adhere to the print platform and help the printer compensate for my table, which was not perfectly level.

The total estimated print time for the arm is about 32.5 hours, although as mentioned earlier some parts can be printed together (the estimate was done using the print preview function of Afinia's software - my actual print time was difficult to calculate because I was still iterating through designs). Including the raft material, it uses 842.8g of filament, which means it can be printed from one 1kg roll.

Most of the parts have "flat" sides that should face the platform . Many of them also have fairly delicate tabs for holding the cables, so take care when you remove the raft and support material. Study the stl file first to get an idea of where the most delicate areas are