Circuits Specialists 3D Printed Robot Arm




Introduction: Circuits Specialists 3D Printed Robot Arm

I found out about Circuit Specialists (CS) when I do some research for my Rover Repair Robot. The company offers the best servo motor for the price, and, I did an instucables on how to modify these servo motors. You can click here to find more information about the modification and about the company.
After speaking to the product manager and sharing my instructable's page I got a call from the company couple days later. Very please with the projects page, they offered me a temporary partnership to run a workshop at Arizona State University. The company had scheduled a robotic workshop at ASU on April 6, and they would love to have their version of 3D printed robotic arm using the company servo motors however the workshop is about a month away. I made a list of things need to be done, design the arm and the control unit, coding the arm and facilitate the workshop.

The workshop with IEEE ASU Chapter was a great success, to some team members that was their first time hand on a robotic arm. I was very excited to explain to the students about my project and the history of the industrial robotic arm. Some of the students came up to me later to have some very interesting questions about robotic arm and system control theory.

The company and I decide this project would be open sources. Which mean we will upload all STL files and the code for this 3D printed robotic arm. That is a reason why I write this instruction to be a basic guild for assembly and coding. Now lets start making, Makers!!! :P

Step 1: Plan of Attack!!!

The workshop's time was one of the greatest challenge for me, since I only have 1 hour and 30 minutes for a presentation, electronic assembly, upload the code, hardware assembly, testing the control unit. I also had to make sure my presentation not too long because I want each team has most of their time to be "hand on project".

The picture at the introduction speaks for the size of the audience that day, it was 5 CSRA kits with servo installed ready for the workshop. I design each of the parts so that they could hardware assembly before the workshop, save us some time. My main goal for the workshop was showing the students the important of following the instruction, upload the home position for the CSRA to the final step of the assembly, connect all components together.

I acknowledge this is one of the most common problems in the robotic field. Any type of robot you can name it, quadruped, humanoid, etc. only can work efficiently if they were homing the their home position properly, and robot arm is no different. Failing to "homing" your robotic project properly could cause a ripple effect to later performing of the project and could cause the significant decrease in the life span of the robot.

To any makers that want to 3D printing these parts and build one for your own work table, I will post step by step how to assembly all these components. Most of these parts are friction fitted, however, I still have indicate hold for you to screw in 2 of the servo screws.

Step 2: Base Assembly.

Most of the picture speak for themselves, however if you have any question just leave them in the comment area, I promise that I will answer them as soon as possible. : D

My first advice, you should already have the CSRA code ready and also check out the PowerPoint that I put together for the workshop. It will explain the electronic components in this project better.

My second advice, you should pre-connect all the servo to the microcontroller. Open the CSRA source code in the Arduino Enviroment, in the void loop, you could uncomment this line of the code to "home" all your servos.

void loop()
//homePos(); <====
//Arm_IK (15 ,5 ,1) ;

By "homing" your servos now, the job would be much easier later when get to the final assembly step.

Step 3: Main Arms Assembly.

Step 4: Gripper Assembly.

Step 5: Final Assembly. "Homing"

If you did take my advice and " home" your servo at the beginning now would be your pain. We need to connect all servo to the microcontroller, upload the CSA code with the homePos() uncomment.

The first thing you may notice id the rotation base was not centered, which mean you have to undo the base and redo the first assembly test with the servo plug into the microcontroller. This way your robot arm will face the right direction.

After upload the homePos code to the Arduino and have all the servos plug in, connecting all the part orientate the same way like the picture and screw in the servo's screw to secure everything in place.

Congratulation, you are done with the basic assembly and coding. There will be part 2 where I explain more about the control unit, battery source, and Inverse Kinematic. However, the source code I have provide you have the Inverse Kinematic Algorithm and PotControl Algorithm, please feel free to play around with it.

If you have any question, please leave on the comment box below and I will answer as soon as I can. Thank you.

Step 6: Circuits Specialists Robotic Arm Competion .

The students joined the workshop had a blast at the CSRA competition at the end. Some of the team did not follow the instruction causing the robot arm to be malfunctioning. Some of the team take too long to assembly the robot causing them time to practice with their robot. And that is all part of the game, if you follow the instruction, " homing" properly, practice with your robot, you will win.

There are lots of improvement on the CSRA design and the workshop structures that I could do for the future workshop. For now it was a great opportunity and experience, and it is only possible because of Circuits Specialists and IEEE ASU Chapter and of course you, Makers. I am greatly appreciated.

Any questions please leave it in the comment box below, and I will answer you as soon as I see it. :D

Circuits Specialists website :

Servo Motor :

Servo Shield :

Robotics Contest 2016

Participated in the
Robotics Contest 2016

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    Question 3 years ago on Step 2

    Where can I find out how many parts of each stl I need to print?

    Khang Nguyen
    Khang Nguyen

    Answer 1 year ago

    Hi Topgun574,

    Sorry for the late reply.

    You only have to print each part once.

    Thank you for the question.


    3 years ago

    Couldn't print robot arm cause most of the files has no heat target!


    4 years ago

    Nice integration of Tinkercad with circuits!

    Khang Nguyen
    Khang Nguyen

    Reply 4 years ago

    Thank you.

    Check out Mr.K the 3D printed humanoid Robot on my youtube channel.

    Just4Fun Media
    Just4Fun Media

    5 years ago

    Nice design. How much weight can the robotic hand hold?
    Have a great day! :-)

    Khang Nguyen
    Khang Nguyen

    Reply 5 years ago

    Thank you Just4Fun Media to be the first one to comment!

    To answer your question it is vary on the servo motor that you use for your project. In this case I am using Circuits Specialists servo motor, it is about 6 dollar each.

    Here is its spec:

  • Weight: 13.8g
  • Dimension: 22.8x12x31 mm
  • Stall torque: 3.1kg/cm (5.0v); 3.5kg/cm (6.0v)
  • Operating speed: 0.13sec/60degree (5.0v);0.08sec/60degree (6.0v)
  • Operating voltage: 5.0~6.6v

    Therefor the CSRA should be able to pick up anything from your pen holder, pen, marker, eraser, etc. The final goal for the project is a table top robot where it pick up pens and stuff that you use on the table and put it back to the pen holder.

    Note: I personally think the CS servo motor provide plenty of torque for the project size. However I recommend print out the battery holder STL file that I provide. It will increase weight to the base and shift the central of gravity toward the back and increase satiability. And you have a place for your electronic.

    Again, thank you very much for tune in. Let me know if you have any more question.