ANTHONY NISTOR // ROBOT ARM

Printed Servo Robot Arm

A 3D-printed arm on a rotating base. Servos move the shoulder, elbow, and wrist, and a printed holder puts a pen on the page.

SEE IT WRITE VIEW THE PHOTOS
// SYSTEM ARCHITECTURE

How the Arm Is Built

The arm is printed in purple and bolted together at each joint. A white ring sits on the base so the whole arm can turn. The servo cables run to a printed box that holds an ESP32-S3 and a PCA9685 servo driver. With a marker in the end mount, the arm writes ROBOTIX ONE.

  • Printed Links Purple printed segments, joined with screws, run from the flanged base up to the pen.
  • Servo Joints A servo turns the base. More servos lift the shoulder, bend the elbow, and set the wrist and the pen.
  • Control Box An ESP32-S3 and a PCA9685 PWM board sit in a printed enclosure and drive the servo cables.
ARM_MOTION.LOG ACTIVE
1. BASE

The flanged tower turns on the white ring

YAW
↓ Move out over the page
2. ARM

Shoulder and elbow set the reach

REACH
↓ Lower the pen
3. PEN

The wrist holds the marker on the paper

WRITE
// WRITING

ROBOTIX ONE on the Page

The end mount holds a marker. The arm sets the pen on the paper and writes ROBOTIX ONE.

PEN_ON_PAPER.JPGWRITING

Pen on the Paper

The printed holder clamps a marker. The wrist servo keeps the tip on the page while the arm draws the letters.

// HARDWARE & SOFTWARE

System Component Breakdown

01

Printed Arm

Purple links, a flanged base, and a white turn ring, held together with screws.

02

Servos

Hobby servos in the base, shoulder, elbow, and wrist, including a DS3225 at the wrist.

03

ESP32-S3

The controller board in the printed box, with a USB port for power and programming.

04

PCA9685 Driver

A PWM servo board that takes the servo plugs and sits above the controller.

// PROJECT MEDIA

Build Photos

The finished arm, the pen writing ROBOTIX ONE, and the boards in the control box.

Finished Arm
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Finished Arm

The purple arm on its base, with the control box beside it.

Writing
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Writing

The pen on the paper, with ROBOTIX ONE written down the page.

Pen Mount
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Pen Mount

A printed clamp that holds the marker at the end of the wrist.

Wrist Servo
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Wrist Servo

A DS3225 servo at the wrist, behind the printed tool plate.

Open Joints
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Open Joints

The arm on the bench with the servo covers off during assembly.

Control Box
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Control Box

The ESP32-S3 and PCA9685 wired inside the printed enclosure.

// SLIDESHOW

All Project Pictures

16 photographs and drawings from this build.

20260908_103355.jpg 1 / 16
20260908_103355.jpg
// TECHNICAL SPECIFICATIONS

System Parameters & Metrics

PARAMETER SPECIFICATION / VALUE
Structure 3D-printed purple arm on a flanged base
Base White turn ring under the shoulder
Joints Base, shoulder, elbow, wrist, and pen mount
Actuators Hobby servos, including a DS3225 at the wrist
Controller ESP32-S3
Servo Driver PCA9685 PWM board
Enclosure Printed purple control box
End Effector Printed pen holder
Shown Writing ROBOTIX ONE