Introduction: 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.


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

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

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%

Step 3: 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:

Step 4: 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

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

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.

Step 7: Middle 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 mid curve L Pin to the Mid Curve U Horn. Ensure the hole and the servo prong are on the same side.

2. Attach the mid curve L Horn to the Mid Curve U Pin. Ensure the hole and the servo hole are on the same side.

3. Place the two connected piece side by side, with the circular hole on one pin/horn facing the servo hole on the other pin/horn. The (servo) holes are facing inward, towards each other.

4.Attach the braces in their correct orientation, and connect the two linked pieces. See picture.

Step 8: Routing Cables

-Route the cables through the lines in the prints by aligning with the trench (the lined holes in the pieces with periodic overhangs)

-Gently push the cables through the holes in the top rotating base so the cables dont get tangled. However, you should finish the base portion of the project FIRST- otherwise, the wires simply interfere with the base assembly.

Step 9: Base Assembly

First take the base with the circular hole and place the circle with the servo horn hole underneath and place the other circle on top, effectively sandwiching the base between the two circular pieces. Attach the base that has the servo holder underneath

Step 10: Control Panel Assembly

The control panel is fairly easy to assemble

Materials list:

1. Buttons

2. Super Glue

3. Spool of solid core wire/or jumper wires

4. Potentiometer

5. LED(Any color)

First make sure the buttons fit. If they don't either make the holes slightly larger/smaller on TinkerCad by downloading the file, finding the cylindrical prism and make it hollow/solid to change dimensions.

Solder wire onto the the buttons(Make sure you differentiate between both of the ends)i.e. black for the right only

Solder 3 diff. color wires to the potentiometer

Solder 2 different wires to the LED(Note positive and negative end)

Superglue the buttons in after pushing wires through

Bundle all the red wires and solder one wire to all of them(Look at the pictures above for clarification), wrap the solder in electrical tape for safety

Superglue the potentiometer

Superglue the LED into place

Step 11: Add the Circuit

Adding the Circuit is fairly simple, it just consists of adding the buttons and eventually the servos to the circuit board. For the servos, in order of left to right, the far left port is for the micro-servo for the gripper, next one is the upper servo, then the middle, then the two lower servos and then the base. (Left to right from the orientation of the resistors pointing down). For the buttons, first gather the bundle of red or black leads and plug that into the port 5V for buttons. Next starting from the potentiometer, plug in one of the wires into the 5V potentiometer and the other one into the Gnd for potentiometer. The third wire will be plugged into the arduino in the next step. The order for the buttons is very important so follow the pictures and written instructions closely. The button that points up that is the farthest from the potentiometer should be plugged into the far left port on the circuit board and the buttons that goes down should plug into the second port. Then the next button that points up should go in to the 3 port and so on until last down button.

Step 12: Plug in the Arduino and Servos

So for the for plugging the Arduino into the circuit board, there are 16 points. 5 for the servos, 8 for the buttons, and 2 for ground and power. The first ones are easy; take two jumper cable and connect from the gnd and 5v on the arduino to the gnd from arduino(on circuit board) and 5v on the circuit board. The 5v should go to the 5v and gnd to gnd. For the servos and buttons, order matters. For the servo's, from left to right plug in the jumper cables into ports 13-8 in that order. I.e. the far left port on the circuit board should have a cable connecting into port 13 on the arduino(See pictures for extra clarification). Same thing for the buttons except for the last 2 ports. The far left button port should have a wire connecting it to port 7 and so on till port 2. The last two ports should plug into ports A3 and A4. For reference, use the electronic diagram pictured in the precious section that helps detail the wiring. Plug the last potentiometer wire into port A0 of the arduino.

Step 13: Closing Up the Base

This part is a bit difficult as its hard to compress all the circuitry into a tiny box. Of course, ensure all circuitry is completed and successfully tested before compressing the top of the base onto it. Take the other two base pieces and fit together and slide into the other base.


Step 14: Attaching Arm to the Base

Attaching the arm to base is very easy. First route the cables through the base. Then make sure the screws are screwed properly into the servo and prongs. Then place the bottom two ends through the holes on the top circular base.

Step 15: Finished!

Marvel at your perseverance and creativity navigating through this daunting project!