The Polyphemus Filament Dryer

I haven’t written about 3D printing in a while, but I have both kept at it and actually doing a bit of market research–I’ve been considering either building an MMU or getting a multi-material printer, but I haven’t made up my mind yet, and the tariff war isn’t helping.

But one of my checklist features for any upgrade was is having integrated drying capabilities, so when EIBOS reached out to me about their Polyphemus filament dryer, I was intrigued.

Disclaimer: EIBOS sent me a Polyphemus and 3Kg expansion kit free of charge, and as usual this article follows my review policy.

Even though all my filament storage boxes have big, hulking car-grade dehumidifier bags, I have felt the need to resort to a dirt cheap filament dryer for PETG and other hygroscopic filaments, since it makes a significant difference in print quality. But the one I had was a simple, bit noisy box with a heater and a timer, and while it works well enough to keep around as a backup, it was a bit of a hassle to use.

I was curious to see how the Polyphemus would fare, but also how much of a difference it would make in terms of the overall experience. Print quality will always be a function of the filament and the printer, but the drying process itself can be a bit of a hassle.

The Polyphemus came in a kit–actually two kits, since I also got the skirt/extension to add enough height for 3Kg spools, which was welcome.

Assembly was pretty straightforward since (other than the extension) it was all done with the exact same kind of screws (always a good thing in kits) and the instructions were abundantly clear, so it took around 30 minutes, and even then mostly because I needed to clear some desk space.

That consisted mostly of laying down a part of the frame, slotting in corner rods (which look like aluminum extrusions but are actually some form of polycarbonate), sliding the acrylic panels in between, and fastening it all together.

I didn’t take any pictures of the assembly process, but here are some of the parts and a couple of pages from the manual, which I found to be very clear and easy to follow:

My first impressions of the Polyphemus just after assembly were very positive:

• Even if it is a kit, the build quality is great. The frame is made of what I assume to be polycarbonate “extrusions” that feel solid, and the combination of those and the acrylic panels make it feel solid and well-made.
• You get spare parts for the motor and some fixtures, which is a super nice touch.
• It has a built-in power supply, which allowed me to get rid of a power brick and rationalize cabling a bit.
• The cover is huge, but easy to handle and the lack of a hinge means you can take it off and put it back on easily, although running the filament through the top outlets will always be a two-step operation. But it provides a clear, unobstructed view of the filament rolls from every angle, so any tangles or spooling irregularities are plain to see (this is a marked improvement over my previous dryer, which is only partially transparent and has a fiddly cover).

As I started using it, I was pleasantly surprised by a few nice touches:

• It has five outlets for filament–two at the rear next to the dessicant compartments, and three through the top cover (the middle one is for 3Kg spools). I ended up using one of the top outlets for my enclosed printer (as seen above), but I might move it above my printers later on, and having the option to route filament through top or back is quite welcome
• It has dual dedicated dessicant compartments, which are easy to access and refill. For now I just tossed in a couple of bags of silica gel, but I will have a go at dropping in granules later on since the grills are fine enough to keep them in place. I don’t see a need to have two kinds of dessicant in there, but I suppose it’s another option.
• It is designed to rotate filament rolls automatically as they dry (with a few different speeds), which makes for more uniform drying and is done quietly and slowly enough that it doesn’t cause any tangles.

As to the drying process itself, the display and controls are easy to read and use, with a simple interface I found intuitive and that has presets for most common filaments (PLA, PETG, ABS, TPU, ASA, etc.), including a memory function for custom settings and power loss recovery (which feels like a luxury, but is actually a nice touch I was surprised to come across in the manual).

It is rated to go up to 70^oC (which is more than enough for most filaments), and the drying time is adjustable from 30 to 24 hours (with a “permanent” mode that keeps the dryer on indefinitely, but which I haven’t tried). I haven’t tried the permanent mode, but I used the target humidity mode for a couple of rolls of PETG and it worked great–and, importantly, it was very quiet.

I have been using it for almost three weeks now and have had no complaints–I tried mostly PETG because that is what I have the most trouble printing, but both PETG and PLA prints have come out great–I drop in the filament a few hours before, tap out the drying settings, and eventually start printing (typically in late afternoon). I haven’t had any issues with stringing or other artifacts that are common with wet filament, and the prints have been consistent, although I still need to tune the filament settings a bit more to take full advantage of the dryer.

The Polyphemus is a great filament dryer that feels like a luxury item if (like me) you’ve never had something that went beyond heating things based on a timer. The build quality feels solid, the design is well thought out, and the drying itself is effective, although I am not really in a position to do a hyper-scientific comparison with my previous dryer.

But I now have empirical evidence that rotating the filament as it dries makes a substantial difference (at least for the PETG I have been using), and the fact that it has a built-in power supply and a couple of extra features (like the memory function) fit quite well into my setup and workflow, so I am happy to have it around.