I’m taking the time to write this quick review this in hopes that manufacturers will read this and converge on a good dryer solution (c‘mon Bambu, this is an easy-win!).
Background
I’ve used a variety of filament dryers and and found them all to have their issues.
I’ve owned and then gotten rid of:
eSun eBox lite - noisy, low max temp, does not vent moisture out
Sovol SH01 - noisy, low max temp and low power, does not vent moisture out unless you follow their after-thought work-around of keeping the lid ajar
Sunlu S2 Fanless version - does not vent moisture out, screen and power plug position prevents you from positioning it in a space efficient way on your work space
Eibos Polyphemus - so many issues with this product - main one being it does not reliably turn your filaments (which is its headlining feature) and very poor ergonimics when trying to feed filament
When looking for a new dryer, I skipped over:
Creality Space Pi - lid opens backwards - seriously?
Sunlu S4 - this looks OK but having two double dryers is about the same price and offers much more flexibility
Food dehydrator/air fryer - noisy, bulky, janky
I decided to chance it with an unknown brand which I couldn’t find reviews for as it seemed promising when I saw it at Formnext 2024. I purchased two units of “R3D D1 Filament Dryer” at the show. They cost 50 euros each, and are normally sold for around 60 euros each. I also bought 2x Sovol/Comgrow SH02’s which is not covered here.
Pros of the R3D D1
Quiet operation - there is an exhaust fan but it’s very quiet compared to printers or other dryers and I don’t mind having the dryer on nearby.
Exhaust fan (not recirculating fan) - removes damp air and less damp air is drawn in from other openings - no need to occasionally open the lid or keep it slightly open. I believe this is actively controlled by reading internal humidity as the fan is off when starting. This is a huge quality of life improvement.
Max temperature software cap is 100 deg c. Marketing literature says 75 deg on one website, 70 on another, I managed to get it to 75. It can probably go higher if I cover it or if it’s a warm day. Max temp is limited by low heater power and lack of insulation.
All around even heating this even drying - no jet of hotter-than-set-temp air shooting out from a PTC heater creating uneven drying (like the Sunlu s2 first design but better)
Lid opening is on the front and the lid doesn’t swing past the back of the unit (it’s designed to be wall mountable)
Built-in LED
Cons of the R3D D1
One of two units I got was reading the temp wrong and was not heating - opened it up to see that the thermistor wires were twisted and possibly shorting - untwisting the wires fixed it.
There is no quick and easy way to tell if the unit is on or off.
Paper manual is incorrect on how to turn it on (it says double tap the on/off but that will turn it on then off, and combined with the previous point - this is a frustrating start)
No way to fix a 4mm OD PTFE tube to the top outlet (I’ll have to design and print something for it… I’ll prob just use some masking tape instead)
It doesn’t tell you the set value and the present value of the temp at the same time - show both. Many other dryers do this.
A double spool option. I bought two but would have preferred one double for cheaper. (In comparison, my SH02’s double dryers were 64 Euros each)
Plastic rollers are noisy
What I would change on the R3D D1
Forget about wall-mounting - I think a very few people would want to put 4 holes in their wall for a filament dryer when one PTFE tube can easily route filament where it needs to go (thus also don’t worry about the front bottom filament exit). Instead of supplying wall mounting hardware (it comes with screws, drill-aid sticker, and bottom filament exit hardware), the cost could go towards supplying a length of 4mm OD 2mm ID PTFE tube.
Protect the thermistor - it’s just hanging out.
An indicator, maybe a small LED - to show it’s on, even when the backlight Of the display is off. (We don’t need a cheap light show like the Sunlu s2/s4 though, it’s not a child’s toy. Just one LED would be great.)
Some thin insulation foam to let it get to 80 deg C easily - this is enough to dry nylon in a reasonable amount of time. Slight incrase in power will also work. 80 deg C would be a great sweet spot for most home users that like to dabble outside of PLA/PETG.
Top and front filament exits with 4mm hole for a 4mm PTFE tube to fit snugly into - exit path tangent to spool for easy feeding.
Thanks for the thoughtful and thorough post!!! This is what quality posting is all about.
I went this route too and was wildly disappointed in the options I had. I ended up going with Creality PI because for under $65, it was the least suckiest choice. I posted a side by side here.
Yeah… in the words of Forest Gump, “Stupid is as Stupid Does”. Let’s be candid, these idiots, and I choose that word deliberately. Are aiming at the lowest common denominator buyer. They are looking for pretty, not functional. All of these latest generation boxes like the Sunlu and PI are made by the same industrial designer and forgot that when designing something, form is far less important than function. But so long as there are fools willing to part with their money rather than rewarding quality, products like this will continue to dominate the market.
However, in my case, the completely stupid lid design for the Creality Pi was too much for me so I designed a stop for it. It can be found here
I included STEP files so that others can improve on the version and I see that at least one person already copied it with adaptations(although they didn’t give me credit😠).
I am new to printing and drying and also.looking for the perfect dryer. Disclaimer, I am not too concerned what it looks like and may build and/or print my own. I would like two, two filament dryers. Reach up to 100*C and have rotating spools.
Have considered using a plastic hard sided igloo cooler or 1/2" R-Tech EPS foam board covered with poor man’s fiberglass from Home Depot. Idk if a cooler would survive continuous 100*C temps. Not sure if I would use forced air or heat pad. Inkbird makes a accurate thermocouple but no humidistat to to turn the heat on and off.
Most or all of the single bay filament dryers can have their performance greatly improved with a dry air purge. Ambient humidity and the filament’s own moisture content slows down and limits the drying process. It’s like how sweat doesn’t evaporate well on a humid day. This is why the door props help especially during about the first third to half the drying cycle.
A dry air purge helps sweep the humid air out of a dryer and keeps ambient humidity air from creeping in. It greatly reduces the humidity in the dryer which speeds drying up while letting filaments dry more thoroughly.
It’s simple to do, too. And pretty cheap. A medium size aquarium pump is plenty and it’s no trick to turn a container of silica gel beads into a drying column so air has to travel through the beads where it drops almost all moisture.
I use an 800g bead column in my drying and that has enough capacity to dry around 30 spools of filament at my location where relative humidity runs on average 40-50% in the house. After that air passes through the column, to the accuracy of the meter I used, after drying 15 or so spools, exit air was still metered at 2% relative humidity. It makes a huge difference in drying. I do not see water effects in my prints and the quality is way up. No interlayer adhesion issues, Bambu PLA silks (the problem child being replaced) print beautifully, PETG HF prints great, and I print using the stock Bambu profiles. No retraction or z-hop modifications needed.
It sounds like a tall tale or a panacea but it works.
Here’s the hygrometer reading at 2% for the air coming out of my drying setup about midway through where I change the column out.
Here you can see it can purge with a pretty fair flow rate (but this uses up the silica gel faster since more ambient air flows through it). (Older version of the air dryer I use had text on it but that caused air leaks so it was deleted)
And here are two prints using the same spool of PETG HF. First is straight from the shipping bag and the second is after drying. Same settings and same model.
So you are pre drying the air going into a dryer? Must be a heat pad dryer then? I’m really trying to learn. That said, I’ve read that you need to heat the filament to promote drying from the inside of the filament strands out. Furthermore, I wonder how well the filament in the middle of a tightly wound roll dries? How is dry air getting to those strands in the middle of the roll to dry them out… Lastly can you.please link the hydrometer that you show going down to 2%RH? I read those round ones are maxed out at 10%RH and not very accurate. Thanks
Yep - pre-drying the air. I use a Sunlu S2 modified to let me introduce the dry air at the bottom (humid air is less dense than dry air so rises so adding the dry air at the bottom creates a natural sweep up).
I don’t know that heat pad or not matters except the ones using the ceramic heaters generally have fans. They’re great for even heating but the mixing volume being stirred up slows the purge process. I don’t know which factor is more important.
Heat is essential for faster and better drying. It’s what helps the water into the gas phase to be removed.
About the inner strands - they aren’t near as isolated and closed off as people think. Filament strands have pits and cracks all in the surface which are huge compared to the size of a water molecule. They bounce around like crazy and eventually find their way out. It’s slower than if it was a single strand in free air but all comes out in the wash. The water does get out.
Many think of the drying process the wrong way I believe. The gas phase is like 3D billiards with molecules and a few atoms flying around every which way. The movement is kind of astonishing. The speeds molecules move in a gas are proportional to temperature and inversely proportional to molecular weight. Water is light - way lighter compared to O2 and N2 and is moving at over 2000 ft/sec but hits something else every 130 nm on average at room temperature and 1 atm. They are buzzing around like mad.
It’s not that the dry air has to flow into the filament wraps (but it does). It’s that the water finds its way out. The lower humidity in the chamber helps the flow direction out of the filament by providing a gradient. It’s kind of mind bending but a physics text will explain it well.
The hygrometer in the photo is Amazon ASIN B07YY1FB9D. Search for that number on Amazon and it should be the first choice. The headline is “ SMARTRO SC42 Professional Digital Hygrometer Indoor Thermometer Room Humidity Gauge & Pro Accuracy Calibration”
Added - one thing about that humidity meter and likely any that use the same type of sensor - they get slow as you near the low limit. Not sure why but response time seemed to get really long even though I had pushed as much air out of the bag it was in as I could a number of times where the air was already stable at low humidity. I had finished drying a spool and popped the tube into a bag with the hygrometer. It had been running somewhere around 10 hours before the tube got stuck in the bag and it still took about an hour to hit the 2% number and stabilize (the flat trend arrow next to the number).
Here’s link to a paper at ResearchGate that shows micrographs of regular PLA and wood-filled PLA. I would guess the smoother wood-filled might dry slower since the gaps would be smaller if tightly wound. But look close at the “edge” and you can see it’s still rough. If you notice the scales they are 500 um and 200 um for the little scale bars. A water molecule is about 270 pm across - about 1,000,000 times smaller than the 200 um bar. There’s tons of room for water molecules to find a path out.
I saw your review before buying my dryers, it’s a good post
Regarding the dry air input - yeah it is better to supply 10% RH air but this exhaust fan right here in the picture below does OK, the RH reading is constantly about 20%. The ambient RH at ambient temp is about 50% where I am, and when it gets sucked into the dryer and heated, it’s about 10-20%.
I can’t speak to the accuracy directly of the round humidity meters but the sensor is behind a small grill a bit and not especially exposed. The big complaint I’ve heard about them is people will set them out and see different numbers and attribute that to poor accuracy.
What I’ve found is if I seal a bunch in a plastic container and let them sit they pretty much equilibrate very close to the same temperature and humidity. I can’t speak to other people’s experience with them, but the ones I’ve bought and use seem to be fairly accurate (at least to agreeing with each other) and the spec sheet says they will be within something like a percent or two of the correct value. I haven’t found any duds yet but maybe I just got lucky.
You can always qualify them by doing the same thing - seal multiple hygrometers in a container and see how they do. Toss or return any duds.
In the air dryer I specifically obstructed the air path by the grill to help divert air into the measurement area and the response is pretty quick. The biggest issue I have with them is range. In hindsight I wish I had bought ones that can also read the 0-10% part of the range because I peg all of mine at 10%.
And stock dryers work great for many people. Ambient humidity has a huge effect. My humidity was high enough that I started seeing moisture effects with PLA which took me down this path.
Part of my testing included using just the aquarium pump to flush air out just like a fan does. No desiccant in line. It certainly helped drying but drying would still stall - under the conditions I have.
That’s the big thing about comparing dryer effectiveness between people with different climates where they dry - relative humidity of the ambient air is almost always (that I have seen) not controlled or many times even mentioned (you obviously did mention it) but it can make or break how well a dryer actually performs.
But another thing is stuff like PLA is easy because you don’t have to dry it much to control moisture issues. Go to the really hygroscopic filaments and using dry air can make a big difference.
Drying the air isn’t necessary for everyone. The commercial dryers do work to varying degrees. But what dry air does for me is take out the guesswork and I hit lower humidities and moisture contents faster compared to my tests without dry air and without dry air, drying in my S2 would stall. In my tests it absolutely made a difference. But again, not everyone needs it.
When printing soft TPU, having a near-frictionless feed, from above does wonders.
Most dryers fall down in two ways:
-Small, poorly designed bearing/roller assemblies that are no where near good enough to feed soft TPU without lots of stretching and other feed problems.
-No suitable feed hole that allows the filament to smoothly feed downward directly into the extruder, bypassing all PTFE tubes.
For as many issues as the Sunlu S1 Plus has, its rolling resistance is fantastic, and it has a hole in the front that can be used to feed TPU downward.
I have a SpacePi for my hard filaments - it is a better dryer overall. But I keep the Sunlu around for soft TPU.
I think the Kickstarter market is ripe for a slightly more upmarket dryer/feeder that solves all of these problems. A higher price point would be just fine if it:
-Hit 90-100c evenly throughout
-had no hot-spot problems
-had adjustable exhaust vent for humid air
-had good ergonomics
-multiple filament output ports for use with or w/o ptfe tube, above and below style feed.
-adjustable rolling resistance… some filaments need a little resistance to prevent rollback/tangling, some need as little as possible…, also needs to do this well for plastic and soft cardboard spools.
-up to 72hr timer (many are 48)
-I don’t need presets. Just a bright display showing current temp, target temp, RH, time remaining.
-quiet
I would take max 80 if it’s a significant price difference (and a lower fire hazard if it’s not from a reputable manufacturer). The new Sunlu I saw at Formnext goes to 110 but they had to go to double-walled panels to allow that.
The R3D D1 appears to have actively controlled fan venting - this I really like. It just needs a flap that closes when the fan isn’t on.
In the spirit of the recursive masturbatory pursuit of 3D printing greatness that so many of us subscribe to (3D printing parts for our 3D printers to fine tune them for 3D printing, so that we can 3D print better parts for our printers…), maybe we should create a printable design with a place to simply slot-in a PTC heater, LCD & controller. Could probably base a lot of it on the BOMs of the chamber heaters that are already available to print.
I’d print the base parts in ASA-CF for dimensional accuracy and heat resistance.
Then, I’d do the door portion in clear ABS - it is one of the higher-temp clear filaments.
I’m not sure exactly what you’re asking but if it is are people keeping track of go/no go moisture contents, I’m not aware of any.
About the second question, that might be most efficient and in keeping with filament only needing to be “dry enough”, but at least for me it’s not worth it to treat filaments differently. Others may have good reasons and do it though.
But also, filament in storage doesn’t really dry much when it cools down from drying even with desiccant in the container with it. The desiccant is there to scavenge water before the filament grabs it.
If you aren’t having water issues though, you’re already set.
I went with PrintDRY, an Australian manufacturer selling theough Matterhackers.com. itll hold two spools and has outlets for feeding filament to my P1S. I like everything about it except its high temp is 75 Celsius. That was OK until i wanted to print some filaments that required 85C and 110C; which i for making fixtures for my woodworking tools. In those cases i use our convection oven which does well; then I feed from my PrintDRY set to 75C. If anyone finds a dryer that provides higher temps than 75C, I would appreciate hearing about it.
