This Nifty Diameter Sensor Checks 3D Printer Filament Consistency

If you’re still typing “1.75” into your 3D printer slicer software, there is a very good chance that your print quality is subpar. Actual physical filament diameter values are critical for achieving great prints and Sasa Karanovic’s WInFiDEL DIY Wi-Fi 3D printing filament diameter sensor can help you collect those.

Your slicer software uses the filament diameter value as the basis for all volumetric calculations, so any inaccuracy will affect every aspect of every print job. The worst thing you can do is assume that your filament is actually 1.75mm in diameter. At the very least, you should use calipers to measure a few different points on your roll of filament to calculate an average to input into your slicer. But Karanovic’s sensor constantly does the work for you, measuring filament diameter and making the data available over Wi-Fi, Bluetooth, or a physical USB connection.

This is a derivative of the InFiDEL sensor developed by Thomas Sanladerer. WInFiDEL has a few upgrades, including the use of an ESP32 microcontroller that allows for the Wi-Fi and Bluetooth connections. As filament passes through WInFiDEL’s body, it pushes up a roller that lifts an arm. That alters the distance between a magnet mounted at the end of that arm and a Hall effect sensor that measures the strength of the magnetic field. The arm acts as a lever, exaggerating the effect of filament diameter inconsistency in order to make it easier to measure, like a mechanical version of analog signal amplification.

After calibration, this is both precise and accurate. But it is worth noting that this only measures the distance between the two points touching the rollers. If filament had perfect cylindricity, that would reflect the diameter. But filament cylindricity can be just as inconsistent as diameter, so this is never going to be perfect. It should, however, be much better than the current industry standard “measure a few points with calipers” method.

The best part of the WInFiDEL’s design is the versatility. Karanovic programmed the firmware as two separate systems. The first measures filament diameter as often as it can and logs the data, tracking the running average, most recent measurement, mean value, and so on. The second system is a bit like an API and it lets other systems make requests to retrieve that data.

This firmware makes WInFiDEL easy to integrate into existing workflows. 3D printer firmware, like Klipper, can make requests whenever it wants to get the data it needs to adjust flow in real time in order to compensate for inconsistency. Stefan from CNC Kitchen was even able to use WInFiDEL in his filament extrusion system.

If WInFiDEL intrigues you, you can find all of the files necessary to build your own over on the GitHub page.