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3D-Printed Robot Arm

Introduction: 3D-Printed Robot Arm

Picture of 3D-Printed Robot Arm

Hi! We are Kevin, Surya, and Tejas from Irvington High School. This is our 3D printed robot arm project that we made in our robotics class with Mrs. Berbawy. The original project blueprint for this arm was posted by Instructables user Beaconsfield. Our Instructables will follow her basic directions, as well as have our own experiences and fixes to the difficulties we encountered while completing this project.

Let’s get started!

Step 1: Gather the Parts

Building a 3D printed robot arm and programming it to move is undoubtedly on the challenging side of the project spectrum. As such, there are many, many materials that you’ll need, as listed below. Included with each part(s) is a shopping hyperlink.


  • 4 Servo Motors ($12.09 each)
  • 2 Mini Servos ($3.79)
  • 8 100-ohm Resistors ($3.16)
  • Electrical tape ($6.66)and duct tape ($7.12)
  • Superglue ($3.83)
  • (Green) LED ($5.27)
  • Printed circuit board ($5.19)
  • Jumper cables ($11.99)
  • Nuts and Bolts (16 x 8-32, 1/2 inch long) (Kit is $14.99)
  • Arduino Uno ($22.00)
  • Male-Female Headers ($0.68 each)
  • Male-Male Headers ($0.74)
  • 6 Servo Horns (Must fit BOTH mini and standard servos)(approximately $0.40-0.50 each)
  • Spool of Filament(PLA or ABS) ($25.00 to $40 approximately)

For the robot arm functionality, you will need access to:

  • A decent computer to run and upload Arduino code
  • Soldering Iron ($7.50-$20)
  • Dremmel ($40.87)
  • Pliers ($6.45)
  • Wire Strippers ($22.25)
  • Wire Cutter ($10.97)
  • 3D Printer (We used the Makerbot Replicator 2)

By no means are the specific products linked required in building the arm; any standard part should suffice.

Step 2: 3D Printing Your Robot Arm Parts

Picture of 3D Printing Your Robot Arm Parts

After the lengthy process of assembling all your materials, you will now endure an even lengthier one: 3d printing the robot arm parts. This process will take a week at minimum to complete, and most likely several accounting for damaged pieces and failed prints. To minimize frustration, please print using a sturdy and decent quality filament. It is recommended to print pieces using the recommended infill density (listed below) to minimize breaking or damaging pieces.

WARNING: Do NOT blindly print pieces. Each piece with an overhang (a part of the piece that hangs over air) will need additional supports in order to finish printing. It is recommended to use the Meshmixer program to automatically create supports for these kinds of pieces. Either get experienced using Meshmixer to print pieces or have a someone who already is do it for you. It is NOT a simple program to use.

For convenience, it is probably a good idea to print pieces by arm section (gripper, base, etc.) so you can work on assembling that section while other pieces are printing.

The attached zip file at the bottom is the intellectual property of Instructables user Beaconsfield.

Recommended Infill Densities:

Base Bottom Buttons Box – 55%

Base Bottom Rotator – 35%

Bottom (Base) Rotate Box – 45%

Base Servo Mount Curve – 45%

Servo Mount Curve Mirror – 30%

Top-Buttons Box – 45%

Top-Rotator Box – 50%

Gripper Base 1 – 30%

Gripper Base 2 – 25%

Gripper Pair – 35%

Lower Brace Horn, Brace Pin – 25%

Lower Curvehorn Cable – 40%

Lower Curve Pin – 45%

Lower Curve Servo – 35%

Mid-Brace L – 40%

Mid-Brace U – 40%

Mid Curve L Horn – 40%

Mid Curve U Horn – 45%

Mid Curve U Pin – 55%

  • final stls.zipfinal

Step 3: Coding Your Arduino

Picture of  Coding Your Arduino

The arduino serves as the CPU of the robot arm- essentially, the arduino contains the code and sends signals to move servos, which in turn will move the robot arm.

Download the code editor and load the code to the program. IMPORTANT: Test the code on the servos first. It is essential that the servos are compatible with the code syntax. If they aren’t, the arm is useless and immobile.

The code below is also the intellectual property of user Beaconsfield:

  • Robot Arm Arduino Code.zipRobot Arm Arduino

Step 4: Building the Circuit Board

Picture of Building the Circuit Board

The circuit board is a simple to make by concept but somewhat tedious to actually build. Ensure that before you begin on the board you have all the required parts listed below:

1) Circuit(Any size as long as it’s not too small)

2) 6 3-pin male to male headers(Make sure they fit in the board before soldering)

3) 2 4 pin male to female headers

4) 1 6 pin male to female header

5) 2 8 pin male to female header

6) 8 100 om resistor

7) Spool of red and black solid core wire(any color works)

It is recommended to tape headers down to the circuit board while soldering.

Tip: Instead of just using solder and connecting, cut a small piece of bare wire and use that as foundation to connect all the parts.

*Original electronics schematics diagram are from user Beaconsfield

Step 5: Gripper Assembly

Picture of Gripper Assembly

The gripper is likely the easiest and fastest piece to assemble, so it may be a good idea to print these parts first. Ensure that all pieces have the correct supports on their stl files before editing.

To assemble the Gripper:

  1. First take the piece that has the two knobs and place the micro servo in the hole as seen in the photo
  2. Take the two gripper gears and place on the 2 knobs(make sure the servo horn fits)
  3. Third take one of the side pieces and place the second micro servo in it(Make sure it has the correct orientation with the horn facing out)
  4. Place both side pieces on the bottom piece
  5. Place the top piece effectively “sandwiching the gripper”

Step 6: Lower Segment Assembly

Picture of Lower Segment Assembly

Be gentle with piece insertion: The prongs will likely break if inserted and pulled at an angle. Because of this, superglue/duct tape is recommended. This occurred with us many, many frustrating times- don’t let it happen with you.
Listed below are the files that comprise of this piece.

1. Attach the Lower Curve Servo to the Lower curve horn. The servo hole on the lower curve horn should be aligned with the convex part of the lower curve servo.

2. Attach the Lower Curve Horn Cable to the Lower Curve Pin. The pin and the servo hole should be aligned.

3. Place the two connected piece side by side.

a. The convex part of the Lower Curve Servo faces outward, as does the Lower Curve Horn’s servo hole.

b. The pin of the lower curve pin faces outward, as does the lower curve horn cable’s servo hole.

4. Connect the two pieces with the braces (ensure correct orientation). Refer to pictures.


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