Tools
Screwdrivers, drill, enclosure-safe drill bits, wire cutters, and a wire stripper.
Before You Start
The goal is a clean, robust scale that is easy to wipe down, with no exposed wiring during a brew day.
Wiring
Flexible wire, jack connectors, PG7 cable glands, and an RJ9 cable for the platform.
Safety
Work with power disconnected. Check 12V polarity before connecting the Dial or the valve.
Software
After assembly, use the software guide to flash the firmware and calibrate the scale.
Wet environment: this project is intended for a garage brewery, but the electronics
still need protection. Close the enclosure, use cable glands, and prevent liquid ingress.
Shopping List
The purchase links below preserve the affiliate links from the project README. Each card shows the
first product image extracted from its affiliate link and downloaded locally into img/.
M5Dial
The M5Stack Dial provides the ESP32, Wi-Fi, round screen, and rotary encoder. It keeps wiring low and gives the brewer a physical interface that remains usable with wet hands.
Unit Weight I2C
The Unit Weight I2C converts the load-cell signal into data the Dial can read. Keep the wiring short and mechanically protected inside the enclosure.
Unit Relay
The Unit Relay switches the optional 12V solenoid valve for keg filling while keeping the control signal separate from the valve power path.
VEVOR Scale
The VEVOR postal scale platform is robust, affordable, and suitable for heavy brewing vessels. Its RJ9 connector makes integration easier and keeps the platform replaceable.
RJ9 Cable
The RJ9 cable keeps the scale platform connection removable and avoids hard-wiring the load-cell cable directly into the enclosure.
Spunding Valve
The spunding valve is only required for keg filling. It remains the mechanical pressure regulator while the scale controls the filling stop by weight.
Solenoid Valve
The normally closed solenoid valve gives the controller a safe way to stop filling. If power is lost, the gas path closes.
1/4 Adapter
The adapter helps integrate the solenoid valve and spunding hardware into the gas-side assembly used by the keg-filler function.
Waterproof ABS Enclosure
The enclosure gathers the electronics, protects the connections, and leaves only the useful external cables: scale platform, power input, and optional valve output.
PG7 Cable Gland
Cable glands provide strain relief and help keep splashes away from the electronics inside the enclosure.
Jack Connectors
Jack connectors make power and optional valve wiring easier to disconnect for service or transport.
12V 3A Power Supply
The 12V supply powers the build and shares the same voltage family as the solenoid valve used by the keg-filler option.
Hardware Assembly
Build the scale path first, then add the valve-control path only if you plan to use keg filling.
Prepare The Enclosure
Position the M5Stack Dial so the screen and rotary encoder remain accessible. Then mark the required exits: 12V power, RJ9 scale cable, and valve output if the keg filler is installed.
- Mark all holes before installing the electronics.
- Install PG7 cable glands for every cable that leaves the enclosure.
- Leave a small service loop inside the enclosure so connectors are not under tension.
Install The VEVOR Platform
Place the platform on a flat and stable surface. Route the RJ9 cable into the enclosure through a cable gland, then connect it to the I2C weight reader.
Simple integration: keep the RJ9 connector when possible. It lets you replace
or disconnect the platform without redesigning the mechanical assembly.
Connect The I2C Weight Reader To The Dial
The weight reader converts the load-cell signal into readings for the M5Stack Dial. Connect power, ground, and I2C according to the labels on your actual modules.
| Connection | Purpose |
|---|---|
VCC / power |
Powers the weight-reader module with the voltage expected by that board. |
GND |
Common ground between the Dial, the weight reader, and the power supply. |
SDA and SCL |
I2C bus between the Dial and the weight reader. |
Before power-up: check the exact markings on your boards. Do not trust wire
color alone; confirm polarity and continuity with a multimeter.
Distribute The 12V Supply
The 12V 3A power supply is the main input. Use jack connectors for a clean power entry, then distribute power to the modules that need it.
- Clearly identify positive and negative on the jack input.
- Keep a common ground for modules that communicate with each other.
- Insulate connections with heat-shrink tubing or suitable terminal blocks.
Add The Relay And Solenoid Valve
For keg filling, the relay drives the normally closed 12V solenoid valve. If the system loses power or restarts, the valve returns to the closed position and filling stops.
- Mount the relay inside the enclosure, away from any possible liquid ingress.
- Route the valve output through its own cable gland.
- Install the valve on the gas path associated with the spunding valve, not on the beer line.
Pressure: the spunding valve remains the pressure-regulation device. The
solenoid valve provides automatic control; it does not replace pressure adjustment.
Close And Protect The Assembly
Once the connections have been checked without load, secure the modules, tighten the cable glands, and close the enclosure. No bare conductor should be reachable during use.
- Check that the Dial knob rotates freely.
- Make sure the scale cable does not touch or constrain the weighing platform.
- Label external connectors if multiple outputs look similar.
Checks Before Software Setup
These checks prevent you from debugging in software what is really a hardware assembly issue.
Free platform
The platform does not touch the enclosure, cables, or workbench when a load is placed on it.
Strain relief
The RJ9 cable, power input, and valve output cannot be pulled out by a light tug.
Polarity checked
Positive and negative on the 12V input are verified before connecting electronics.
Valve closed at rest
For keg filling, the solenoid valve must be normally closed when the system is unpowered.
Next: Software Installation
When the hardware assembly is complete, flash the firmware and run the scale calibration wizard.
Next step: open the
Software Installation Guide, flash the M5Stack Dial,
configure Wi-Fi, and run calibration. Final weighing accuracy depends heavily on calibration quality
and on the mechanical stability of the platform.