Open source robot arm to extrude organics

Research resident Andreea Bunica is using her time at Green Lab to develop an open source hobby robot arm to extrude organics.

Having conducted her first months research and protoyping she has successfully produced her first iteration of a robot arm using an existing open-source arm (Dobot desk arm) redesigning the frame and firmware code to do the following:

  • Incorporate a syringe organics extruder
  • Provide stability and accuracy through low cost fabricated PLA parts and lasercut pieces
  • Incorporate an Android app-controlled robot functionality

By Andreea Bunica, Research resident


Additive designing
Fig. 001 concept render version 01

To start the build process Andreea modeled an accurate version of the Dobot desktop robot arm and created template lasercut files.

The original Dobot arm is fabricated out of cut steel sheets, for mobility freedom- aiming to create a low cost, but effective version, the parts for the first design of the organics printing robot arm have been fabricated through a combination of lasercutting and 3D printing. One of the main aims throughout the ongoing design process is to fabricate the majority of the robot arm components (including couplings, bearings etc.) through 3D printing.

Here is an example of what the first tape-bound casing version looks like:

Tape bound first version
Fig. 002 first tape-bound casing version

Still in it’s draft form the robot arm is currently composed of lasercut plywood parts for the main and minor arm, and 3D printed components for the base case, as well as 3D printed stepper couplings and base fixing elements to ensure smoothness of rotation.

Working through a trial and error fabrication ethos each iteration and prototype enables testing and informs constant re-design in order to work towards creating a refined, cohesive and functional end design.


first draft of the base casing
Fig 003. First draft of the base casing

The construction of the base is divided into three main sections:
1. Fixed base
2. Rotating base
3. Base casing

Base construction
Fig 004. Base construction

You can find the .obj files for each part here

1. Fixed base
For the first draft design, the base is the weight point to give the arm stability and to create a solid motion pivot point for the rotating element.

Files/ Components:

  • Base cylinder (screw-in base for fixing the rotating element)
  • Cylinder neck (glue-on the base cylinder to provide enough height between the fixed and moving elements in order to avoid friction)

Fixed Base
Fig 005. Fixed base

2. Rotating Base

The rotating bases attaches to the fixed base through a screw-in fixture attached to the stepper motor coupling. For the first draft, the case fixing legs are glued-on.


  • Screw-in stepper fixing
  • Gasket ring
  • Base plate
  • Coupling
  • Casing fixing leg
  • Stepper plate
  • Stepper motor 1

Rotating base
Fig 006. Rotating base
Rotating base
Fig 007. Rotating base
Rotating base
Fig 008. Rotating base
Rotating base
Fig 009. Rotating base
Rotating base
Fig 010. Rotating base

3. Base Casing

The draft casing (supporting the stepper motors) slots-in to the base plate and is secured with fixing legs.

Files/ Components

  • Base Casing
  • Casing Fixing Legs

Base casing
Fig 011. Base casing

ASSEMBLY (so far)

Assembly so far
Fig 012. Assembly so far

To follow Andreea’s project as it develops you can head to her website