Perfect Measurements: Precision Filling

The Precision Filling Module is a staple in the food and chemical packaging industry. It uses gravity and active weight feedback to dispense materials with sub-gram accuracy, making it perfect for filling spice bottles, coffee bags, or liquid vials.

The Feedback Loop

The system operates on an active feedback loop between a scale and a valve:

1. Tare: You place an empty bottle on the scale. The Arduino zeroes the weight (Tare).
2. Bulk Fill (Fast): The Arduino opens a large solenoid valve (or a strong servo gate) to 100%. The material pours in rapidly.
3. Dribble Fill (Slow): When the scale hits 90% of the target weight (e.g., 90g out of 100g), the Arduino partially closes the valve to slow the flow to a trickle.
4. Cutoff: The instant it hits 100g, the valve snaps shut, preventing any overfill.

Required Hardware

• Arduino Uno/Nano.
• HX711 Load Cell Amplifier: Essential for converting the tiny analog voltage changes in the metal scale into heavy, readable digital weights.
• 5kg or 10kg Load Cell (Strain Gauge).
• Servo Motor or Solenoid Valve: The dispensing gate.

Calibration Nightmare

Load cells don't output "Grams"; they output raw numbers. You must run a calibration sketch at the start. You place a known weight (like a 500g dumbbell) on the load cell, record the raw number, and then use that as the calibration factor (scale.set_scale(calibration_factor);) for all future measurements!