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FM Essentials: The Sensor

A detailed overview of the Filament Sensor, its function, and how it takes measurements. These essentials are to help you understand how best to use the machine to your specifications.

The Filament Maker extrudes with a collection of features and components working together efficiently. It is up to the user to utilize these tools and ensure that the machine works well.

Table of Contents

Things to Watch Out For
Machine Settings
Safety / Error Messages
Further Information


The singular function of the Sensor is to measure the filament diameter and provide data for DevoVision and the Puller Wheel

For the material to be actively measured, it must be cool enough and solid enough to go through. If the filament is still too liquid or contains still unmelted particles, the Sensor cannot serve its function well. This is exactly why the Sensor is only used during the Finetuning and Spooling phases.


As mentioned in Nozzle Essentials, the industry standard for filament diameter is 1.75mm and 2.85mm. Both the FM and DevoVision have settings for each of these diameters. The measurements are shown on the FM interface, as well as on DevoVision as a graph with thickness in micrometers on the y axis and time in seconds on the x axis. 

Things to Watch Out For

The focus of most extrusions is getting a quality, printable filament. The Sensor measures only a single aspect of this, therefore it is crucial that we always compare the taken measurements with the visual evidence as well.

This means physically inspecting the extruded filament after it has gone through the Sensor (and Puller Wheel) and check for any inconsistencies, like scarring, bubbles, or lumps. You may do this under a light, microscope or even running your finger on the surface of the filament helps with checking the quality. 

PLA colored filament 11

Machine Settings

The 1.75mm or 2.85mm diameter can be set.

Furthermore, a more specific diameter thickness can be be manually set.

Safety / Error Messages

Safety Warnings:

The Sensor does not pose any danger.

However, the Sensor is very close to the extruded filament, which can at some points still be too hot to touch with bare hands. Please use gloves or tools when handling a hot filament!

Furthermore, since the Sensor is only used during the Finetuning and Spooling phases, any other time we recommend covering the Sensor with a piece of silicon sheet or cardboard.

Error Messages:

There are no error messages linked to the Sensor. It either measures a filament as it passes through, or it does not and only shows '0'

Further Information

This article comes handy when the Sensor glasses have become dirty.

Instructions on how to replace the Filament Sensor.

Troubleshooting guide to help when the Sensor shows 'Zero'.

Next essential: The Puller