Clean the Filament Maker optical sensor glass

The windows of the filament thickness optical sensor can get dirty over time. For the diameter readings to be reliable, the windows need to be clean.

Negative effects of dirty sensor glasses

When the sensor glasses are dirty, readings become unreliable. These can include:

  • stuck on one value for multiple seconds (typically 2-10s)
  • stuck on one value permanently
  • value really different from reality

What causes the sensor glasses to become dirty?

Over time, plastic fume can condense on the glasses. 

This typically takes hundreds of extrusion hours to occur, but there are some exceptions. Certain  materials generate a lot of fumes that quickly form a thick contamination layer.

Dust from the working environment can also land on the glasses.

Check the following before disassembling the sensor

Other phenomena can cause the diameter reading to be unreliable:

  • Filament vibrating during the pulling process: because the output is too fluid and/or excessive fancooling is applied.
  • Light interference (very rare): when intense light lands on the sensor from a specific angle. A quick check consists in covering the sensor opening with opaque tape.

The contamination often takes the form of a white opaque fog on the sensor glasses. You might be able to see it without disassembling the sensor.

Another quick test consists in placing an item of accurately-known diameter, such as a 2.00mm drill bit.

sensor drill bit

Download our cleaning guide