EvoArm
B✓ Links verified May 19, 2026
Guides and BOM only — orobot firmware does not yet support this hardware.
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EvoArm
A desktop-sized 3+2-DOF 3D-printable robot arm built around Dynamixel smart servos, designed by Ali Shug. Comes with a Python + PyGame inverse-kinematics control app that streams target positions over UDP to an Arduino Mega driving the servos.
Specifications
- DOF: 3 (base swing + main arm + forearm) + 2 (wrist/end-effector)
- Servos: 3× Dynamixel AX-12 or AX-18A (arm) + 2× XL-320 (effector)
- Controller: Arduino Mega 2560 with multiplexed TTL lines via 74LS241
- Kinematics: Python PyIK app (PyGame) with interpolation + reachable-volume visualization
- End-effector: flat touchpad (level with floor, 2 extra DOF)
- Origin: based on LiteArm i2 by Armatec (Thingiverse 480446)
- License: CC-BY-SA 3.0
What's in the source
Design/— STL files for the main arm + Derived Parts + EffectorPyIK/— Python inverse kinematics applicationArduino/— Mega firmware for Dynamixel multiplexingDocs/— circuit and wiring diagrams
Getting started
Clone the repo, print the STLs, source Dynamixel servos + Arduino Mega, wire up the 74LS241 multiplexer, flash the Arduino sketch, and run the PyIK app. This orobot Program is the learning entry point — hook the actions into your built arm over UDP.
🖨 Print Files (32)
evo_Arm_-_608_bearing_cap_Med.stl
evo_Arm_-_608_bearing_cap_Small.stl
evo_Arm_-_actuator_hinge_L.stl
evo_Arm_-_actuator_hinge_R.stl
evo_Arm_-_actuator_linkage.stl
evo_Arm_-_base_center_support.stl
evo_Arm_-_forearm_v2_hinge.stl
evo_Arm_-_main_arm_L.stl
evo_Arm_-_main_arm_R.stl
evo_Arm_-_main_arm_spacer.stl
evo_Arm_-_mounting_bottom.stl
evo_Arm_-_mounting_top.stl
Required Hardware
| Item | Qty | Unit Cost | Notes |
|---|---|---|---|
| Dynamixel AX-18A smart servo | 3 | $130 | Main arm joints (AX-12 underpowered) |
| Dynamixel XL-320 smart servo | 2 | $25 | Wrist / end effector |
| Arduino Mega 2560 Rev3 | 1 | $45 | Main controller, multi-UART |
| 74LS241 octal tri-state buffer IC | 1 | $1 | Serial multiplexing |
| 12V 5A power supply (DC barrel jack) | 1 | $15 | Powers AX-series bus |
| 4.7k–10k pull-up resistors (5V) | 4 | $0.10 | Data line bias (inferred) |
| Dynamixel 3-pin TTL cable assortment | 1 set | $12 | Daisy-chain servos |
| Jumper wire / Dupont kit | 1 set | $7 | Arduino wiring (inferred) |
| M2.5 / M3 socket-head screw + nut kit | 1 set | $15 | Frame assembly (inferred) |
| Half-size or full-size breadboard | 1 | $6 | Buffer IC prototyping (inferred) |
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