FilaWeigher Will Keep Track of How Much 3D Printer Filament Is Left on the Spool

The raw thermoplastic material for FFF (Fused-Filament Fabrication) 3D printers comes in spools of thin filament. Those spools help the 3D printer smoothly feed plastic into the hot end, but they don’t make it easy to tell how much filament you have left. Most of us can’t estimate the amount remaining with any better accuracy than about a quarter of a spool. You can, however, calculate the amount left if you know the weight of the empty spool and the current overall weight. You can also build FilaWeigher, which is a standalone WiFi web-based weight sensor that costs less than $7.

FilaWeigher will constantly keep track of the weight of your spool of filament, and then make that data available through a webpage. Whenever you slice a new model to print, your 3D printing slicer will tell you precisely how much plastic it will require to complete (usually specified in grams). All you’ll need to do is check to make sure there is at least that much left on your spool of filament. FilaWeigher doesn’t currently integrate with OctoPrint, but the project creator hopes to add that feature in the future. In the meantime, you just have to check it yourself before starting the print.

The two important components for this project are a Wemos D1 mini ESP8266 development board and an HX711 load cell with a built-in amplifier. Load cells are one type of sensor that can measure weight, and the amplifier is there to help make the output easier to read. The load cell fits into a custom, 3D-printable spool holder. The provided code hosts a web page to display that data, and even includes a calibration wizard to help you get everything setup. You can find out how much your spool weighs from the manufacturer, by weighing an old spool, or by subtracting 1kg (or the specified filament weight) from the overall measured weight. For just $7 or so, if you order everything through AlieExpress, you’ll have an easy way to find out if you have enough filament for that next job.