Project Development

Final Assignment: "EX-TERRA-DUR" Terracotta Clay Extruder

 

 

 

 

 

 

For my final project, I divided my tasks as following:

01. Clay Preparation: This is the most crucial step, as it is important for the clay to be in perfect consistency such that the motor can push it out easily and uniformly. Also, if it is too fluid, it wont take the form while pinting.

So, this is my first step towards the final project.

 

02. Structure and Assembly: This includes designing of the form and structure of the extruder in Rhinoceros 5 and fabricating the components using subtractive and additive techniques such as Laser Cutting, CNC milling, 3D printing and Vinyl cutting.

 

03. Electronics and Coding: For this task, I plan to make a board that  would control my output device (bipolara stepper motor) and input device (End stopper).I shall try to embed the controls for my input and output device in the satshakit so that I can easily program it or else would make a board to control both that would programmed using Arduino.

 

04. Device Functioning: Last step would be to get all the steps together and make the extruder work and document it by mounting it on an 3-axis machine and running a code to the machine to fabricate a form using the extruder.

 

Completed Tasks:

01. Clay Preparation:

For this step, I took help of the Clay- Workshop technician at my university Mr. Mahesh who has his own clay workshop in my city and is also an expert who has been working with clay since a long time.

 

Availability: Here, in my country, terracotta clay is available in the form of solid lumps from local potters that is measured in kg.

 

First step is to prepare clay, for which I followed the following steps:

 

What is the deadline? How much time is left?

My final presentation is scheduled on 21st of June, 2017. Hence, my aim is to finish everything one day before the final submission i.e. on 20th June. I have around a week and half left to finish the remaining tasks.

 

What tasks have been completed, and what tasks remain?

I am done with fabricating the components and have also tried and tested the clay consistencies. Further I need to work on the electronics and coding part and get all the pieces of puzzle together.

 

What has worked? What hasn't?

As mentioned, the assembly of all components was successful as planned, Electronics, I havent started yet, hence I need to start onto that.

 

What questions need to be resolved?

The coding is the crucial part, because the board that I have prepared to control my input and output device needs to work. As the circuit is going to play an important role for the functioning of my device.

 

What will happen when?

Currently, my schedule is working correct. The rest of the schedule is as below:

1st June: Complete fabricating all components and recieve the ordered hardware

6th June: Finish electronics design

8th June: Finish electronics production and start programming

13th June: Complete presentation video and slide

 

What have you learned?

Almost all the assignments have been somewhere helped for the final project. The most important learning from the final project is the understanding of measurements that are required to fabricate a machine. And also, understanding of the electronics and the connections and flow of data.

 

 

The progress and process regarding the final project can be seen below:

 

Bowl

Mesh

Filter

Bowl

Measuring cup

Water

Hammer

Terracotta clay lump

Syringe

The following things are needed to prepare the clay. Idea is to break the chunk of clay into fine particles so that there are no air bubbles and lumps formed when we add water to it for extrusion.

 

Mesh Filter: This helps in separating fine particles after we break the chunk into pieces using hammer.

 

Hammer: This helps in breaking the clay chunk.

 

Bowl: One bowl is required to store the fine clay powder and the other is used to store the larger particles of  residue that can be again broken into fine particles by grinding.

 

Water: This will required later to make soft clay that can be extruded.

 

Measuring Cup and Syringe: This is required to maintain an accurate proportion of clay and water.

Below video shows, how I used the hammer to break up the clay chunk into pieces.

Note: Clay should be prepared in an open environment, as terracotta contains a reddish pigment in itself that can leave stains and can be really messy to work with indoors.

As seen above, the roller can be a quick solution for breaking clay particles into fine particles.

Next, a roller can be used to further break down the pieces into finer particles. The image on the side, shows the same. The roller can simply be rolled on to the clay particles like done to spread dough.

Now, I used the mesh filter to sew the clay particles to obtain fine particles of clay. The residue left in the filter can be re-rolled into fine particles.

As seen above, the after sewing it through the mesh filter, only fine particles get into the bowl.

 

Note: This powder can be stored in an air-tight container, and can be used whenever required. It is important to keep it away from moisture to avoid forming lumps again.

Next step is to add water to form clay from powder.

To obtain a perfect ration that can be extruded from a syringe, I measured 50gm of clay in a cup as seen below  and added water using a syringe.

To begin with, I added 15 ml water in 50 gms of clay. I followed to same by following the same process.I mixed the following proportions to test the consistency.

The trick is to add water to the clay powder and let it absorb the water on it own for a few seconds before stirring it.

01

02

03

04

05

Next, I filled the various consistencies in the syringe and tried pushing them to checked the pressure required.

The image shows the various consistencies of the clay that I prepared for testing.

Consistency Testing:

Below are the consistencies and their respective results from the test:

CLAY POWDER

 (Gms)

WATER

 (ml)

RESULTS

50

10

 TooHard

50

15

 Hard but not smooth

50

20

Liquidy

50

30

Too Liquidy

50

40

As fluid as water

CONSISTENCY

NO.

01.

02.

03.

04.

05.

Since consistency 01 was too hard and 02 was too smooth, I needed a consistency between the two. Hence I tried "50gms clay with 17ml water". This time the consitency was perfect. The result can be seen in the video below.

02. Structure and Assembly:

I started this task by making a basic sketch of my extruder. Sketches usually help to given an idea of the components that would be required. Below is the sketch that I make to get started with 3D.

For this, I first took the measurement of the motor and syringe, as I wanted them to fit perfectly. Below are a few images for the same.

Since, I planned to fabricate a device that can be easily fabbed. I tried to work with basic cuboidal forms.

After, completing the 3D, I created a few rendered views and marked out the components to make the assembly more understandable. I also created a GIF image that shows the assembly of all components. The GIF image can be seen below:

Fabricating the Components:

I used 4 additive and subtractive techniques to fabricate my components as follows:

Laser Cutting

3D printing

CNC Milling

Vinyl Cutting

 

Laser Cutting (Week 3):

I decided to prepare a box to conceal my circuit and integrate it in the device. Hence I chose to use laser cut 2.5 mm thick MDF board for this.

 

Preparing the file for cutting:

I made a box in reference to my device such that it can be mounted onto the back plane. Istarted by making 3D using Rhinoceros 3D and then extracted the 2D files by using the command 'Make 2D' in Rhinoceros. The images below show the process of preparing files in Rhinoceros.

I exported the 2D file in 'DXF' format. Once the drawing is imported, laser cutting parameters are set for cutting.

 

The video and image shows the process of laser cutting of the box.

3D Printing (Week 5):

After finishing my 3d design I decided to start fabricating all the parts of my extruder. All the components are very simple and as I wanter to keep my extruder lighter I decided to 3D print all of them with ABS.

 

Preparing the file for printing:

While designing the extruder components I made all the components in such a way that they can be fabricated easily through 3d printing and the removal of the syringe. I started by making 3D using Rhinoceros 3D and then extracted the 3D files by export command and converted all the files in stl format. The images below show the process of preparing files in Rhinoceros.

I imported 3D files in Cura. Once the 3D is imported, all the parameters are set for 3D printing in cura. After setting up parameters, Gcode file is uploaded in ultimaker to print with the setting shown in the image.

 

Images of components being 3D printed.

 

CNC milling :

Once all the 3D printed components are ready, I decided to finish my major component where my other 3d printed components will fix and my motor will be supported.

Preparing the file for milling:

The base of the extruder is designed in such a way that, it becomes most important member and holds all the other members of the extruder. The images below show the process of preparing files in Rhinoceros.

Below images explain the parameters that I used for milling the base.

Below image showing the x/y zero setting and material thickness of material used.

Image showing the pocket cutting path with the selected tabs.

Below image shows 2d profile tool-path and the cutting depth of the material.

Image showing the 2D profile to mill and parameters that are used for setting up the cut depth and tabs..

I used 1/8th Ball Nose bit at the following parameters for all toolpaths.

Spindle Speed: 7500

Feed Rate: 1.5

Plunge Rate: 1.5

Images of components being 3D milled:

 

Vinyl cutting (Week 3):

I planned to make a sticker for naming my extruder to give it a more personalized touch.

Preparing the file for vinyl cutting:

I prepared file in Adobe Photoshop. Basically i typed name of the font that i like and saved it as a JPEG file that I then opened in Cut studio to cut in vinyl. The below image shows the process of using cut studio.

Images for Assembly:

03. Electronics and coding:

I required a circuit board that would help me run a Bipolar stepper motor for my 'Clay extruder'. I wanted to redesign the board designed by Neil, but unfortunately the ICA4953 motor driver required to run the motor wasn't available in my area. Hence, I was trying to make a circuit using A4988 motor driver.

I started by modifying the Satsha-kit and added the required components based on the connections that I understood from Jari's board. I came across Jari Pakarinen's work for FabAcademy 2017 and found out that he had prepared a board using the A4988 motor driver to run a bipolar stepper motor. Hence, I decided to redesign the board and try it myself to see if the board was helpful.

 

I added provision for 12V power supply that would power up my IC and the IC would further supply power to the motor. Also, Satshakit had a lot of pins, which I reduced depending on the connections that I would require for my end stopper and top stopper. Initially I added a voltage regulator to maintain the current flow to the IC. I removed it later as it was not required in the circuit. I could directly power up the IC to transfer power to the motor.

I embedded the schematic of my input and output boards  in one schematic where I used Atmega 328P  as my microcontroller.

Next, I made the board and checked it with the design rules.

Further, I included holes for the purpose of mounting and completed the circuit.

 

 

 

I milled and prepared the circuit and it was working, but only for the ease of adding pins for the future users, I shifted the headers for the motor a litte away. The revised png can be acessed below:

Above are the png file for my TERRAPIN board. EAGLE files can be accessed here.

Below are the images that show the milling process and stuffed board:

Programming:

I prepared the codes to run the board.The codes I used are attached below and the video showing the working of the code can be seen beneath the codes.

 

// codes for TERRAPIN board " EX-TERRADUR"

// codes by Chandni Chhabra

//http://archive.fabacademy.org/archives/2017/fablabcept/students/203/

 

const int stepPin       = A1;

const int dirPin        = A0;

const int topStopper    = 3;

const int bottomStopper = 4;

 

void move( int times, int stopperToLookFor ){

 //  loop stayes 'times' times.

 //  One Loop iteration moves motor aporx 8.4 millimeter

  while( times-- ){

      for( int x = 0; x < 200; x++ )

      {

        // check for inputs from stopper To Look For

        if( digitalRead( stopperToLookFor ) == HIGH )

        {

          // if stopper sends HIGH, Means plate has reached to its end

          // so simply return back to the parent loop function

          return;

        }

          //make some step with motor

          digitalWrite( stepPin, HIGH );

          delayMicroseconds( 2000 );

          digitalWrite( stepPin, LOW );

          delayMicroseconds( 2000 );

      }

    }

 }

 

void setup() {

  // Sets the two pins as Outputs

  pinMode( stepPin, OUTPUT );

  pinMode( dirPin, OUTPUT );

 

  //set two stopperButtons as output to reduce high voltage.

  pinMode( topStopper, OUTPUT );

  pinMode( bottomStopper, OUTPUT );

}

void loop() {

 

  digitalWrite( dirPin, LOW ); //Changes the rotations direction

  // if move is performed 10 times, it will move about 8.4 CM which is a littlebit less than height of the injector

  move( 2, topStopper );

 

  digitalWrite( dirPin, HIGH ); //Changes the rotations direction

  move( 2, bottomStopper );

 

//  terminate the process after single execution of the sequence.

 exit(0);

}

 

 

Stating the pin numbers of the respective, step, direction from the A4988 IC and stopper switches connected to Atmega 328P on the board

Movement for the plane that pushes the plunger:

Commands for the Plane that pushes the plunger to look for the top stopper button and then count the number of steps to move forward.

Functioning for the end stopper and top stopper:

Commands for the top stopper and end stopper act as switches for the functioning and movement of the motor to move the plunger plane upwards and downwards.

The below diagram can be referred for pin numbers:

Videos showing the working of the board:

Final working:

After all trials, I moved forward to extruding terracotta clay using my extruder.

I prepared the clay as per the consistency I mentioned above under 'clay preparation' on this page. It worked smoothly.The video of my extruder extruding terracotta clay can be seen below: