My DIY filament dryer using 3d printer heatbed

My DIY filament dryer using a Folgertech Kossel & heatbed set to 40c. This plastic roll seems to have quite a bit of moisture in it. Since I did not have a filament dryer & my oven will only go down to 150degs F, I came up with this idea. I am using klipper firmware & set my [idle_timeout] for the temperatures to 3600 seconds, so it will only heat for an hour at a time in case I forget about it. I put a weather sensor on top of the filament to see what the acutual temp was on top. It has taken 10 minutes for that sensor to get to 27c. Probably need several hours, but will see what 1 hour does. I was going to use a large metal cooking pot, but this big glass bowl fit on nicely & I can also see the filament this way.

[attachment file=102572]

I need a filament dryer. I guess I need to get a Kossel.

Seems like the water would leave the filament, but stay in the air around the filament. You need something to keep the heat in, but let the water out. Or maybe you could put some of those anti-moisture packs in there with it to absorb it first.

Is there a good test to determine the moisture in the filament?

I don’t know of a good test. You should be able to use any printer’s heat bed for my method. You could put a bowl of rice or silica packets in the enclosure with the filament when it is drying on the heat bed. That should suck up all the extra moisture. My filament is not spitting like it was before which is good sign it worked. I will probably get a food dehydrator similar to the one in this video at some point, but the model he is using is currently $200. I like this style as it could also be easily used for filament or dehydrating fruits & stuff. I just don’t want to spend $200 on one, maybe near Christmas they will be less expensive. Since my wife is interested in dehydrating fruit, it will be easier for me to buy one of these. Some of the other DIY dehydrator ideas of the round version show having to cut away part of the enclosure making it unusable for its original purpose.


I should probably do this as well… I’ve seen folks use desiccators for jerky making, but this method is potentially cheaper.

Is that condensation on the bowl? Maybe a cover with a few small holes and add some air circulation (a small 40/50mm fan should work, just need to get the air moving - but not so fast that it overpowers your heating)

At the risk of convincing someone to build a contraption that could start a fire… I wonder if it makes more sense to have a dedicated RAMPS board and heat bed, and putting the temperature sensor in the air around the filament instead of the bed. You could then have some air flow, and the heat bed closed loop control would compensate. The danger would be, it’s possible it would take full power to heat up the air, depending on the amount of insulation/air flow. Then the heat bed would be on 100% all the time, so you’d have to size it and the electronics, and anything it touches to handle that.

There must be other humidity control systems out there too, but I like this idea.

This stuff that looked like condensation is actually noise in the image. I shot that at ISO 32,000. I forgot I had the camera set to F16. I usually have it at F8. I have it set to auto ISO with 32,000 as the upper limit. I can actually get nice photos up to ISO12,000.

I would not feel comfortable leaving this setup alone just in case there was a fire problem. At 40c it should not be unless there is a wiring issue. I was also thinking a dedicated heat bed for this would be good, but if you have to buy all that stuff, you may as well get a good food dehydrator & would be a lot safer & more useful. I ran an hour & half print with this filament after only an hour drying time & I only had some spitting of the filament the 1st few minutes. It had been continuous before. I am printing a Fire Engine Red openRC Formula 1.

Probably cheaper to use a heating pad (already has a built in thermostat) and a “safe” enclosure to put it and the spool(s) into… hmmmm…

Keep your extinguishers handy and check their expiration dates!

Fun fact: I kept an extinguisher handy when I flew large scale gas RC years ago. Never had to use one in 15+ years. More recently flying LiPo electric planes/drones… 2 battery fires in 1 year… (both in LiPo bags inside a 50cal ammo box).

Cheapest food dehydrator on Amazon is about $35… they don’t list the internal diameter, I bet the 3D printer guys already know the answer.

Yeah, but you don’t want the heater to be at the temperature, you want the air inside the container to be that temperature.

I haven’t needed to dry PLA, but I do dry nylon filament (bulk weed whacker line). I’ve had good results using a slow cooker with the lid slightly ajar to allow moisture to escape.

  • Al

Don’t think I had much moisture in my filament after all. When my printer started making that same noise again today after being without problems for a couple of days, I did some more research on the titan extruder & it seems it is a bad bearing in the case cover making a creaking noise. They have since changed the type of bearing they use. I thought that noise was just a lot of moisture. I found a replacement cover with the 2 updated bearings for $5 with free shipping from Matterhackers, so I ordered them to see if that fixes my problem. 2.5 years of printing with that bearing seems reasonable to me.

Build a box and shove this in it:



That looks like it’s just a heater. How does the moisture leave?

My mom used to have a similar heating rod in her baby grand piano to keep the humidity down. Believe the piano tuner called it a hotrod.

Not sure. It’s used in gun safes, and those things don’t have vents on them. I just know they work.

Could probably just put a small vent slit on the top of the enclosure for the moisture to escape from.

Basically it warms everything up keeping water from condensing. If you have vents, it lets the moisture out, but also back in.