Whether it is for telling different component drawers apart or knowing more details about the food one is eating, labels are everywhere and contain vital information. Most modern label makers rely on replaceable cartridges of thermal paper, which then go through a dot-matrix print head to receive their lettering. But because they rely on expensive, proprietary software and lack the charm of older manual label makers, Andrei Speridião decided to add new IoT functionality to one.
Priced at a mere $10, Speridião's original, manual label maker uses a different kind of paper than the more expensive thermal printers. Rather than being covered in a coating of thermally-sensitive film that turns black when heated, this paper turns white when pressed/imprinted. This allows the user to rotate a dial above the paper strip, click a button, and watch as the dial presses the desired letter into place. One major issue with hardware this cheap was the lack of reinforcement and strength, which led to inconsistent results that would have to be addressed later.
Speridião started his project by first deconstructing the existing label maker and removing its most important component — the dial. This part was then attached to the end of a 5V stepper motor and put into the bottom of a custom 3D-printed enclosure. From here, a secondary 5V stepper motor rotates a much smaller cog to pull in the label paper for embossing. The use of a mini SG-90 servo motor proved to be far too weak at applying enough pressure, meaning a modified, improved design was in order.
The primary stepper motor was swapped out for a larger NEMA17 motor along with an A4988 stepper motor driver. Additionally, the SG-90 servo was replaced by a more suitable metal-geared MG-996R servo which could apply more force. Original testing of the printing mechanism was handled by an Arduino Mega 2560, while the web app was served by an ESP8266. In their places, a single ESP32 replaced both of these components with one of its CPU cores handling networking and the other controlling the hardware. After finishing most of the code, everything was assembled into a compact 3D-printed box and sealed shut.
In order to get input from a phone into an embossed label, Speridião created a small web application that is hosted on the ESP32. When the device first starts, it displays its local IP address along with a dynamically-generated QR code for quickly accessing the interface. The webpage then enables visitors to enter their label's text and see a preview in real-time, as well as enter any one of five special characters or change the spacing.
After the text has been entered and sent to the ESP32, the label maker's top OLED screen displays what is currently being printed along with the current progress. Every stamp of the dial is accompanied by a blink from an LED, and two blinks indicate the label has been finished and cut.
To see more information about this label making device, you can read Speridião's detailed write-up here on Hackaday.io. The completed device also only costs $70, and he encourages anyone with the same manual label maker to convert it into a fully connected, automated E-TKT machine.