Introduction: SBDD (String Bot Drop Deposition)

The construction of this bot was a part of my master thesis experiment called (Tectonics of droplets) in the studio of Architecture and performative design in SAC,Frankfurt am main under guidance of Prof. Mirco Becker.

Introduction :

A wire bot is nothing but a simple bot made using three stepper motors and an arduino board to control the movement in cartesian space. The wire bot was used in my design experiments to control the micro level of particles in Architecture and the outcome are the droplets which as a designer gives a large degree of freedom to control the formation of parts on a per drop basis. The process involves heating of wax in the beginning, which is then controlled by dripping it in the desired location using the wire-bots. The droplets of wax are at liquid state when it leaves the nozzle and gradually changes from semi solid to solid when makes a contact with the surface of the environment or the other drops. This process differs a lot from the contemporary 3d printing process also known as Fused Deposition Modelling (FDM) which extrudes the material continuously. The difference in Robotic Droplet Deposition (RDD) is to control the size and flow of the droplets by actuating the motors.

For a drop to exist as a defined entity, a degree of immiscibility is required between at least two phases (solid or liquid), so that the cohesion of elements can give rise to stability in the surface of each droplets. For this a textile form work is used in my case for the droplets, it has three important consequences. Firstly, the textile would both act as a form work and reinforcement for the compression based material like wax. Secondly, unlike steel it doesn’t corrode and so ultimately unnecessary dripping of wax just to clad the reinforcement is got rid of. And thirdly, the synchronization of material and design would go hand in hand giving a larger degree of freedom for controlling. This gives the N number of possibilities for the formation of topologies with wax.

Wirebot Advantages:

The wirebot assisting in my prototype works on kinetic rotatory translation movement. It is made up of four main parts i.e. An Arduino board to control the stepper motors, three stepper motors to operate the movement of nozzle, Elastic strings to hold the nozzle, and an Actuated Nozzle to drip the wax. The advantage of the wirebot is that it contrary to its size and scale it could produce a larger scale products since it is connected by string, the limits of movement is waived off. The range at which it could handle now in the current prototype is it could produce a product of 1m x 1m x 1m. The ease of movement of this wirebot could be a great asset for architecture from prototype to buildable scales.

Step 1: Step 1 : Materials Needed for Assembling the Hardware

Materials needed for construction of wire bot:

1 x Arduino Uno

3 x Stepper motor - NEMA-17 size - 200 steps/rev, 12V 350mA

1 x Synthetos gShield (grblShield) V5

1 x wax melter

1 x peristaltic pump - only needed if the wax melter is unavailable

1 x 3m teflon pipe to with stand the heat of the melted wax and transport it to the nozzle

1 x Drip controller - used from the infusion system ( see the picture for reference)

3d printed parts (STL files attached ):

1 x Nozzle

3 x Motor case

3 x Pulley- One for each motors

Step 2: Step 2 : Assembly and Calibration

The motor are put inside the case and tightened with M3 screws, it should be then mounted on a wooden frame(the one shown in the picture is made from recycled wooden carton) to hold the motors in place as show in the picture. The motors are then mounted at their respective vertex as stated in the diagram .

Configuring the stepper motors:

The stepper motors are then connected by wires to the Arduino motor shield to their respective X Y & Z axes.( If there are confusions regarding pairing the wires of the motors to the shield please take a look at the wiki in rerap printers. Once all the wiring and connections are done its better to test it by sending the G code using Universal G code sender. Once the callibration is over the next step is to configure the software to control the movement digitally.

Connecting the wax melter to the nozzle:

The outlet of the wax melter is connected to the nozzle using teflon pipe with drip controller inserted to the pipe. The optimal temperature for the melting paraffin wax used in this experiment is 540-50 degrees. If in case the specified wax melter isn't available then a fondue pot can be used for the experiment and connected to the nozzle with the help of the peristaltic pump.

Step 3: Step 3 : Configuring the Software

Software Requirements:

Using the software:

The main grasshopper file is opened using rhino and the instructions are clearly available inside it. The motors are configured with the actual default settings. There are two types of models that could be inputted to the bot. One is the 3d geometry and the other is a set of curve.(refer to the diagrams). The nozzle moves according to the specified curve or geometry. The manipulation of these models are provided in the control panel of the .gh file. Please refer to the picture for changing the shape.

Step 4: Step 4 : Troubleshooting and Final Product

Troubleshooting with melted wax:

The images shows the final product. The major problem could be faced is drying of wax in the teflon tube on the way to the nozzle this could be solved by pumping the wax in order to make the liquid flow forcefully instead of falling out of gravity. Since the main aim of the experiment is to drip the wax on the surface or meshes so the wax melts instantaneously due to the drip controller but in the future the design could be improvised and with thermal wires around the PTFE pipe in order to make the flow continuous.

Final product and improvements:

The main agenda of this deposition is to see as a designer how a bot could control the micro elements in architecture the wax is only a lab material for testing it, in future it could be replaced by actual construction materials once the design and experiments are fully tested with professionals.

Credits and disclaimer:

The initial idea of making the bot was borrowed from the students of CCA their experiments can be found here. I am very much thankful to them for documenting their work process to make it clearly understandable for a beginner with no knowledge about arduino and stepper motors. Most of the code in the grashopper file are used from them with additional changes customized for my experiments. But the outcome of dripping the wax is totally different from their concept of extruding the clay.