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This is an Arduino controlled robotic arm I made just from cardboard and small servos. It takes around 2 hours to build. Once built, you can write all sorts of code to make it do anything.

In this instructable, I include two programmes I wrote. One makes the arm move periodically to lift a small object. The other takes input from the user via potentiometers, and moves the arm. The arduino records this movement and plays it in a loop afterwards.

This instructable focuses mainly on building the hardware. It can be divided into three parts. The claw, the elbow and the base.

Material required-

  1. Cardboard
  2. 1 clothespin
  3. 3 servo motors
  4. Arduino
  5. 3 potentiometers (optional)

Tools required-

  1. Fevicol or Hot glue.
  2. Black tape
  3. cello tape
  4. Knife
  5. Ruler
  6. Screwdriver
  7. Pins

Step 1: The Claw

I used a metal clothespin. Attach one of it's halves to the servo motor with tape and fevicol. You can use hot glue too.

Cut out a piece of cardboard of dimension approximately 3cm X 13cm. Attach the servo blade of the elbow to one end with fevicol and tape. This connection needs to be strong as this joint transmits the torque from the servo to the arm.

To the other end, attach the other half of the clip. After these connections dry, attach the claw servo with more glue and tape.

Ensure that the claw closes properly during servo operation.

Step 2: The Elbow

This part is like the claw in the sense that it has a servo motor attached at one end, and a servo blade at the other.

  1. Take 3 to 4 layers of cardboard of dimensions around 3cmX 15cm and sandwich them together Make sure that the longer side is along the cardboard grain, for higher strength.
  2. Towards the top, drill a hole of the dimensions of the servo, and embed it inside the cardboard.
  3. Make 2 cardboard trusses as shown in the pictures with cardboard which can support the claw during operation.
  4. Attach the truss to the elbow with fevicol such that a centimeter of space remains. The base servo will fit in this place.
  5. Coat the bottom surface of the trusses with cello tape to reduce friction.
  6. Attach the servo blade to the base with fevicol or hot glue, and pins. This joint needs to be strong to ensure proper power transmission from the base to the elbow.

Step 3: The Base

All of the arm's operations are within this region.

  1. Cutout 3 to 4 layers of cardboard and sandwich them together with tape.
  2. At the center, you need to fix the base servo. So cutout a t-shaped cavity.
  3. At the center, fix the servo with fevicol or hot glue.. I used the metal gear mg90 servo for the base.
  4. Make sure that the servo is in level with the base. The gear should fit in the space we left between the elbow and the trusses.
  5. There should be enough space in the T- hole for the wires to slip under.
  6. Mark of the circle in which the elbow will rotate with tape.
  7. Coat this circle with cello-tape to reduce friction between the base and trusses.
  8. You can even apply lubricant like machine oil over the cello-tape.

Step 4: Putting It All Together

  1. Attach the claw piece to the elbow such that at 180 degree the claw touches the base.
  2. Tape the connecting wires and jumpers to the side of the elbow pillar.
  3. The elbow pillar should connect with the base servo with little effort. You can make this connection permanent with a screw. I chose to keep it free so that during violent servo movement the arm doesn't get damaged.
  4. Pass all the wires underneath the base through the hole.
  5. Attach one final layer of cardboard to the base, which will ensure that the base servo doesn't touch the ground, and the wires are hidden.

Step 5: The Potentiometer Controller

Connect 3 pots to the arduino analog input pins. Any value will do. I used 10k.

Step 6: Code

I have attached the two codes used in the videos, and described in the introduction.

Step 7: Some Tips...

  1. Make appropriate measurement before cutting the cardboard, or gluing anything together.
  2. At every step of the construction, plan where to put the wires. Otherwise it will be a real hassle in the end.
  3. Give the glue time to dry before powering the servos.

Sorry once again dor disturbing but 2 of my servos are only working. Sometimes first and second work and sometimes 1st and 3rd works but they don't work all 3 at a time. What should I do???
Can you ellaborate more? Send a couple of pics of the arm, the connections and the code.
After making it I understood how hard you would have worked. Praised by your work and waiting for your next project........ :() :):):):):):):):):):)<br>Thanks once again...
Hi Sourav, sorry once again I am distirbing you but can you please tell me how to connect the circuit on breadboard I dont know where to connect power terminals. I think I should connect that triangle in the circuit diagram with the reset button and for gnd I have 2 terminals on my arduino where should I connect...<br>Please reply.....<br>
Just connect 5v from the arduino to a power rail in your breadboard. This is the triangle. Connect all wires connected to the triangle to this power rail.<br>Connect any of the three ground of the arduino to another power rail. Connect all grounded wires to this.
THANKS for your TIME
Hey Sourav, do I need to upload both the codes to run the arm for continuous motion. I mean when I have planned an action, do I need to upload both the codes so that my arm performs the same action repeatedly??? <br>Please reply
<p>No just upload the ServoRecordandPlay. Perform an action when the led at pin 13 is on. After it turns off, the arm is no longer taking input from you, and plays whatever it recorded in a loop. If you want it to repeat another action, just press the reset button and record the action.</p>
THANK YOU
Thanks bro you helped me so much I am almost done with it
Hey how did you power it. I meam is it powered by external battery. If yes than how many volt or is it powered by arduino itself
<p>It is powered by the arduino itself. You can attach an external battery of upto 12 volts to it. </p><p>If you are using servos which require more current than the arduino can source, you can use the external battery with a suitable voltage regulator (like 7805) to power them.</p><p>But that shouldn't be a problem because the arduino only supplies current to one servo at a time.</p>
Thanks and how many ohms potentiometer did you use. I found several like 470 kohm to 1k ohm which should I use
<p>Using a pot of very low resistance gives excellent readings to arduino, but it dissipates a lot of power.</p><p>Using a very high resistance takes in a lot less current, but it messes with the internal ADC of the arduino, and you don't get reliable readings.</p><p>So it is best if you use pots of resistances upto and including 10k ohms.</p>
Thanks bro you are the best!!!
<p>In which college do you study??? I am in 11th and soon will be in college......</p>
<p>how i use 4 servo with play record mode</p>
<p>There is a const int N in the first line of the code. It is set to 3. Just change it to 4 in your code.</p><p>Attach the 4th servo's data pin to GPIO 5, and it's control pot to analogread pin A3 (also called GPIO 17). </p>
Sourav bro I truly loved your project. I am also one such curious kid who wants to develop innovations at home.<br>Always boost your innovation and inspire us too.<br>Regards.....
Thank you for your appreciation.
Please share if you make some more interesting projects like this one
<p>Awesome. This project is the perfect illustration of the fact that you don't need to spend a ton of money to get into robotics.</p>
<p>Thank You.</p>
Sir, we are keen about your project, could you please upload the circuit connection<br>
<p>I just did. I am glad you are interested in it.</p>

About This Instructable

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Bio: I am an electronics and communication engineering student currently in my second year. I have an interest towards micro-controllers, electronic circuits and hardware hacking.
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