Revolutionizing My 3D Printing: How a $2 Humidity Sensor Became My Top Upgrade

There are numerous ways to customize 3D printers. You can modify the software, add decorative lights, create filtration systems, and much more. However, I opted to first invest in a basic $2 humidity sensor before purchasing additional filament. Here’s why a humidity sensor is crucial for my 3D printing process.

Wet Filament Costs More Than the Sensor

I’d Prefer to Pay $2 Now Than to Reprint Later

An inexpensive spool of filament typically costs around $12. Consider the potential loss if multiple spools become unusable due to excessive moisture during printing.

Printing with damp filament can lead to various issues, such as increased stringing, uneven surfaces, and even fragile parts. I strive to avoid these problems when 3D printing, as I prefer pulling a component off the build plate that looks good and is sturdy, rather than damaged due to moisture-related air pockets.

For the price of one filament spool, I would much rather invest in a humidity sensor that allows me to easily check whether my filament needs drying. Since I started using the hygrometer in my Automatic Material System (AMS), I haven’t experienced any problems with wet filament. The heater from SUNLU atop my AMS 1 makes it simple to dry out the filament if the hygrometer indicates high humidity levels.

Another benefit of the hygrometer is its versatility; I can place the $2 humidity sensor anywhere in my office to monitor the humidity in that area, including in dry storage that I don’t frequently use. However, it can be relocated there whenever necessary.

My AMS Already Monitors Humidity, Just Not Numerically

The AMS 2 Pro Revealed What I Was Lacking

My initial AMS was the original model by Bambu Lab, which did not provide a numerical humidity reading. Instead, it assigned letter grades from A to E (dry to wet), and this score was not a straightforward humidity metric. It combined water content, temperature, and relative humidity into a vague evaluation.

The exact calculation for this score was never disclosed, leaving me without a clear understanding of the actual humidity level. Temperature could significantly influence the score, but the first-generation AMS does not offer clarity in this regard.

Upon acquiring the AMS 2 Pro, I discovered that Bambu Lab had resolved this issue by displaying the humidity percentage accurately, rather than relying on an arbitrary scale. While this improvement is beneficial, it doesn’t assist with my older AMS, which I still own.

Thus, adding the $2 sensor to my existing AMS was a far more economical choice than selling it to buy a new version. Since the older AMS functions well, I avoided spending a large amount just to gain humidity readings—a significant win for me.

The Reading Indicates the Environment, Not the Filament

It Acts as a Desiccant Warning Rather Than a Moisture Gauge

After acquiring this hygrometer, I had to remind myself that it does not measure the moisture content of the filament; it only reflects the relative humidity within the AMS.

When the humidity percentage begins to rise, it serves as a prompt for me to check the desiccant to determine if it needs renewing. This may also signify that the overall humidity level in my home (particularly in Tennessee) is elevated, or it could indicate that the AMS needs attention.

Additionally, I know I need to dry the filament if I’m working on an important print, as high relative humidity typically suggests that the filament may have absorbed excess moisture.

It’s important to understand that a hygrometer cannot measure the filament’s moisture percentage directly; it gauges the surrounding air. However, when the air is persistently damp, especially for hygroscopic materials like TPU or nylon, it is highly likely that the filament has absorbed more moisture than ideal.

Whenever in doubt, it’s better to dry it out.

Make Room for the Sensor Before the Next Filament Purchase

A hygrometer is an essential and affordable tool that every maker should have. For such a low price, it’s invaluable in preventing the disappointment of ruined prints.

Personally, I don’t mind redoing a smaller print that takes only 30 minutes. However, I have also faced the frustration of losing hours of work due to using damp filament.