EIBOS Polyphemus Review

The EIBOS Polyphemus makes sense if you regularly dry two rolls of PLA or PETG, or need room for a larger spool. It heats filament—the plastic strand fed into your 3D printer—and can turn the spools while they dry. Its humidity mode can also bring the heat back on between drying sessions.

I’d buy it for that capacity and adjustable drying routine. The rotating mechanism is a less convincing reason on its own: some spools turn smoothly, while others slip or get stuck. And if you mainly want to dry a roll, unplug the dryer and store it for weeks, the Polymaker PolyDryer deserves a closer look.

Will your spools fit the Polyphemus?

Measure your spools before ordering. “Two 1 kg rolls” describes its usual load, but the weight printed on a filament box doesn’t tell you whether the spool fits.

The optional expansion raises the cover to fit one compatible 3 kg spool. It doesn’t make room for two 3 kg rolls. A wide spool may fit where a larger-diameter spool won’t, even if both hold the same amount of plastic. Check any adapter rings too, since they add to the outside diameter.

The standard unit measures 275 × 205 × 317 mm and weighs 2.2 kg empty. Allow extra room above it to lift the cover off and somewhere nearby to put it down. A tight shelf can make loading awkward even when the dryer itself fits.

There’s some assembly: the working base arrives built, while you put together the clear panels, frame and handle. The expansion adds another frame beneath the cover. EIBOS also provides printable expansion files, so check whether your chosen package includes the parts or leaves that job to you. The large removable cover gives you good access to both rolls once it’s out of the way.

How well does the Polyphemus dry filament?

The strongest everyday case is PLA and PETG. A reported trial lasting almost three weeks found consistent prints with both, mostly using PETG and starting drying a few hours before printing. That’s encouraging practical evidence, but it doesn’t establish how much water was removed or how quickly a thoroughly wet spool would recover.

Check which temperature version you’re buying. EIBOS now lists both 70°C and 80°C options, with a 30–80°C range advertised for the hotter version at a room temperature of 25°C. Older results from the 70°C model don’t establish the newer version’s temperature accuracy.

In one reported 2024 test of the 70°C model, a probe placed 5–10 mm below the chamber’s top measured 57°C at a 50°C setting and 62°C at 55°C. Filament was loaded during the test. Heating-power mode, probe calibration and repeatability weren’t documented, so those readings aren’t a reason to subtract 7°C from every setting.

They are a reason to take your filament maker’s instructions seriously. Prusa specifies 45°C for six hours for Prusament PLA and 55°C for six hours for its PETG. Those are material-specific instructions, not universal settings for every brand. Excess heat can soften filament until neighboring strands stick together; the spool itself must tolerate the drying temperature too.

EIBOS provides three heating-power levels and recommends low power for heat-sensitive materials such as PLA. You can save temperature, duration and power in a profile. Treat the supplied profiles as starting points to check against your spool’s instructions.

A PA or PC preset doesn’t guarantee suitability for every nylon or polycarbonate. Prusament PC Blend, for example, calls for 85°C drying, beyond either Polyphemus version’s specified maximum. Choose a hotter dryer for that job.

Finally, the humidity display measures the air near a sensor, not water inside the plastic. A low reading alone doesn’t mean drying is finished. Nor does the heater’s wattage tell you the electricity used over a whole cycle.

How the rotating spools affect printing

Rotation is appealing because it changes which part of the roll faces the heat. What remains unproven is whether it removes more moisture than leaving the same spool stationary under otherwise identical conditions. I wouldn’t pay extra solely for a promise of faster or more even drying.

Some hands-on reports describe smooth rotation. Others report occasional stalls with two full 1 kg spools. Owners have also described rolls moving sideways and binding, or rollers turning underneath a stationary spool. Those are different symptoms; a spool that stops moving doesn’t automatically mean the motor has failed.

One documented hands-on incident involved a loose filament end catching and stopping rotation. Before a drying-only session, secure the free end to the spool and check that nothing sticks out into its path. Watch a newly loaded roll long enough to see that it turns without rubbing or letting strands unwind.

Printing from the dryer is a separate setup. Turn rotation off for the spool feeding your printer, and let the printer pull the strand. One report describes an alternate roller arrangement that allows one side to rotate while the other feeds. Confirm the required roller and instructions with EIBOS for your version before depending on that arrangement.

The Polyphemus has eight filament exits: three at the front, two at the rear and three on top. Choose the route that gives the guide tube gentle bends. An owner using a Prusa MK3+ reported feeding trouble and subsequently changed the tube route and printer feeder adjustment; because both changed, the report can’t isolate one cure.

A top exit may give your printer a better path, but threading filament through the removable cover makes spool changes more fiddly. Try your intended route before committing to a long print.

Using the Polyphemus beside your printer

The front buttons keep routine adjustments straightforward. Option selects the material profile; Setting moves between temperature, heating power and duration, with up/down buttons making changes. There are nine material profiles plus three custom slots, rather than twelve different material presets.

The timer covers 30 minutes to 24 hours, with an unlimited option. That gives you room for longer material-specific schedules without repeatedly starting short cycles. Saved profile settings survive a power loss, but don’t assume that proves a particular drying cycle will resume automatically. After an interruption, check the operating mode and remaining time.

EIBOS lists the Polyphemus manual on its Download page. Use the instructions matching your unit, especially for reset commands; published descriptions differ on the required button-hold duration.

Noise reports are generally favorable: one comparison described a quiet fan and a little motor noise, while an owner sitting about a meter away found it audible but acceptable. Neither supplies a measured sound level. That sounds reasonable for a printer bench, though I wouldn’t promise it will disappear into a quiet office.

Leave room to reach the cover and keep the exhaust unobstructed. If the fan develops an unusual noise or stops working, ask EIBOS for the correct replacement and service instructions. A generic fan recommendation would need verified electrical and physical specifications.

What happens when you switch the Polyphemus off?

Humidity mode and switching off at the wall do different things. In humidity mode, the powered dryer can activate its heater to regulate humidity around your chosen target. If you disconnect the power, that protection stops.

The adjustable top vent should stay open during drying so moisture can escape. EIBOS says you can close it when heating isn’t needed. There are also filament-port plugs and compartments for desiccant—the moisture-absorbing material commonly supplied in little packets.

Those features can help keep moisture out, but a closed vent doesn’t make the whole enclosure airtight. A hands-on inspection of the older model found no rubber gasket at the cover or base. That matters more for storage than whether you can plug an unused filament hole.

Reports that praise its storage features and reports that reject it as a dry box aren’t necessarily describing the same use. Keeping powered humidity control running is different from relying on the enclosure and desiccant alone. Neither view gives you a measured number of days that an unplugged Polyphemus will keep a spool dry.

For longer gaps between prints, I’d move dried filament into a sealed container with suitable desiccant. If you want to keep each roll in its own box through drying, storage and printing, the PolyDryer’s removable sealed-box design fits that routine better. Its standard box holds one compatible roll up to 1 kg, and one dock dries one box at a time. That’s a storage convenience, with a different capacity tradeoff from drying two rolls together.

When the Polyphemus is worth buying

Choose the Polyphemus when you’ll regularly use both spool positions, your material’s drying instructions fit its temperature range, and you can give it a clear feeding route. It’s also worth considering for a wide, compatible 3 kg spool that needs the expansion. Check the actual dimensions before treating that as a reason to buy.

Count the expansion and your storage containers in the cost. Comparing the dryers alone won’t tell you what your larger-spool setup costs, and having two storage boxes doesn’t mean one drying dock can dry them both at once. There isn’t a clear cheaper choice across those different setups.

If sealed storage matters more than drying two rolls together, I’d lean toward the PolyDryer. Its US dock-and-box package was listed for backorder when checked, so confirm availability if you need a dryer promptly. If your existing EIBOS Cyclopes already dries your materials satisfactorily, rotation alone isn’t a strong reason to replace it.

Support terms deserve a check too: EIBOS’s sales FAQ describes a one-year “paid warranty.” Clarify repair and shipping charges with your seller instead of assuming a year of free repairs.

For regular PLA/PETG drying, the Polyphemus offers useful capacity and flexible controls. Buy it with a plan for spool loading and separate storage, and treat rotation as a feature to check with your own rolls—not the feature that settles the purchase.