drying filament modifies temperature??????

Hi. Where I live we usually have at least 70% of air humidity. It makes reaaly dificult to have your filament dry enough to get good prints. Till now I have been drying my rolls in the oven... a bad way to do it in my opinion, if you are not reaaly takeing care of it you will end up ruining a complete roll, bending your rolls, etc. In conclusion, a very unconfortable way to do it specially because once your roll is dry, if you have a long print, like 20hs, you will start noticeing how the filament is absorbing humidity at the end.
So I decided to build a drying chamber. And I didt it pretty well and nice: I have temp control, internal air circulation, etcs. And the once inside, the rolls stays there, the chambers is completly air tight. So once dried, I can pull the filament through a hole and print, so the filament never abosrbs humidity again.
I have a humidity sensor inside. Once dried, inside the chanber humidity stays around 10%. And the quality of my prints are showing a huge impact
Here it cames the "problem" : this chamber is new. I finished it 3 days ago. I did a first drying session, I started a drying cicle of 3 hours. Did some prints and smiled...
Then I decided to take the drying further: I did a 5 hours drying cicle. After that I did another print. ANd here it comes the strange thing: nothing changed in my printer, nothing changed on my setting. But this time, I tried to print PLA, at 180 degrees. It went well at the first layers then I started to have like underextrusion problems. I tried to manually extrude and I noticed that it was somehow hard to extrude. It was like the usual 180 degrees now were not enough. I simply solved the problem rising temperature. Now Im printing at 200 degrees.

I have to say that before increasing temp, I checked many things: there is no clogged noozle (I did and atomic pull, used my 0.4 needle to check noozle). I checked filament diameter, I check my hobbed bolt, etc. Everything was like always.

So I have to ask: anybody knows if a super dry filament need more temperature than another that has some humidity ?

Thanks in advance

I'm no Chemistry wiz, but I do have an idea to look into.

Plastic needs plasticiser to flow well. I learned of this when a mate made a filiment making rig to recycle bad prints etc.

Similar problems. The plastic did not flow well once it had been recycled. The heat in the first printing, then more heat in the recycling process cooked out all the plasticiser. The resulting recycled filament was very brittle and did not extrude well.

I suspect you cooked out too much plasticiser.

I haven't spoken to the mate with the filament extruder is ages, but I think they got a chemist to help out and added plasticiser. I dont think you can get it back in your filament though without grinding it to powder and re-extruding with additives.
Maybe enquire on a chemistry forum?

For now just cook your filament for less time or at lower temp.


I too live in a tropical climate. Summer is coming. I have been pondering the same problem re: oven is too risky and wont work on long prints. Would you be interested in sharing your design? I have some ideas in my head to do something similar, but sounds like your further along than me. Maybe we could work together on it?

NEXT TIME, make yourself an airtight chamber with a bunch of color changing desiccant packs in it in order to dry your filament

---

If you need some help, or don't understand what I just said, feel free to send me a PM anytime

Printer: Prusa i3, 2 E3D v6 Hotends, Arduino + RAMPS 1.4 with a Bypassed 5V Regulator, 400w Insignia ATX PSU, Custom Designed Bowden Extruders

Mongrel Shark: interesting info, actually what you are talking about reminds me one thing I didnt mentioned: the last drying session I did, I actually increased the temperature from 40 to 50 degrees, and time was also longer like 5 to 6 hs... may be was too much... And also I noticed that increasing temperature helped me in this problem but it still feels dificult to extrude. Before this, extrudeing at 180 was easy, and if I increased temp to 200 was noticeable easier... no that big difference dissapered. I think you gave me the answer.

DAgameface: an air tight chamber with dissecant works... but not this well. Once you have your filament roll with a lot of humidity, you wont dry it with only disecant, or at least no in less than a week or more. PET for example, at least here, will absorb humidity in only 4 hs.... Id I have a long print, like 12 hs printing time, I for sure will have overextrusion problems and if I dont watch, a clog after that... An air tigh chamber is a solution for storeing rolls, not for drying and printing in an dried air condition, and I repeat, at least here. Today for example we had 90% humidity the hole day.... There are designs of air tigh chambers with disecants and you can use them to print also without takeing the rolls out of it, but still they dont provide a quick drying solution, and everybody recommends you to use the oven. For me , the oven is no longer a solution, it forces me to stay 4 hs watching the thing.... and the risk of ruining a roll is really high.


My design: it is made of glass (why? just to have a fancy look, and glass has a good temp isolation capability). The door is in the front, it opens and closes. It has a rubber seal so once closed it airtigh. Inside the box I have: an electric resistance enclosed in ceramic (220V). This resistance is controled by an arduino control. It lets me set a temp. The arduino senses temp with a sensor and turns on and off the resistance to keep the desired temp. It also has a temp alarm in case for some reason temp reaches some un desired temp. With this set up, the electric resistance it is turn on only 5 to 10 seconds, with that it is enough. I also have an extra temp and humidity sensor, as a back up. There are also 2 fans, radial fans, so I have a good air movement inside the box and temp is the same all over the box (if you dont have fans, temp is like 3 degrees greater in the top than in the bottom of the box.) There is a set of holes in the glass, on the lower part of the door: air gets in the box dureing the drying process. There are hole on the top of the box: air goes out the box dureing the drying process. And I have a hole in the bottom of the box: the filament being used for printing comes out through this hoel, actually I have a conector here. All these holes are closed when not printing and the ventilation holes (the ones on the door and top) are closed once the drying cicle is finished.
I have a bag of diseccant also: its job is to absorb the little humidy that can come in dureing printing becuse og the open hole where the filament comes out (this hole is 3mm wide, I only use 1,75 mm filaments). The box is working really good right now, can specially see the results with my PET printings.
Heere ar some pictures. Pending work: to print a case for the arduino temp controller , and fancy clamps for the door (right now Im useing tape jajajaja)

Interesting design. I like that you can dry (or de-plasticise) a lot of filament at once and store it safely. Its too big for my desk though I was picturing something just big enough for one roll...

I have been thinking of something much smaller that attaches to the printer. Air would go in and get dried. Maybe with heat or hygroscopic material like Silica. Or with a cooling element.
Once the air is dry enough it can get blown into a heat chamber which the filament passes through on the way from spool to printer. This way you only dry what you use. In really humid conditions some pre-drying of the spool may be required...

I'd build it all for 5v as I use an ATX and don't like wasting power on dummy loads.

A simplified extruder may also be used to feed the filament to the printer at the required rate and avoid tugging as the spool feeds off.

Has anyone tried rice as a moisture absorber? I bet its cheaper than silica, and you can dry it out and re-use...


If you can't fix it with duct tape and tie wire. Its broken. You need a new one

Well, yes, it is somehow big. But I made it exactly for storeing some rolls at the time. And has the same size as my printer enclosure: 50X45X50 cms.
I think we can discuss a lot abot drying filament, but for sure we will not discover anuthing new or something that has not been discussed in the forum. I searched a lot of info, looked for already available comercial products, talk to people in forums about this, etc. Conclusions:

- You can dry your filaments with an air tight box and silica? Sure you can, but the process will take a week, at least till you roll is dry enough, may be more depending on your filament type.
- There is no faster way for drying than useing heat.
- The oven "technic" is dangerous and makes you a slave of it. You risk melting your filament, your rolls, cant controll temp, etc. It works... but it is a pretty basic method for drying.
- there is a comercial product named dribox. It works pretty much as you described what you want to do. A hot box, and the filament passes through the box. A friend bought it. In his own words: "it is crap, I wasted 200 euros" . After he calmed down, he recognices that dries the filament, but very little. And it makes sense: the filaments passes and stays inside the heated box like 20 seconds, 30 secondas AS MUCH. There is no way you can remove moisture that is inside the filament that quick. All people, all forums I have spoken/read speak about 4 hs for properly drying a filament roll.
- Rice? it works, the same as useing salt . But they absorb less water than silica. Silicagel is way more ificient and quick. And silica can be reused, you just need to put it 1 hs in the oven and will be like new. In fact, the silica I have in my dryier get dried when the drier is working (the silica you see in the picture, has a component that turns its color into purple when it is saturated, and it is blue when it is not. The first time I tried my drier, that silica was purple, all of it, after the initial 4 hs, that silica was completly blue.

Well, we ened talking about issues not meant to be talked in this post jajajaja. And by the way: the problem I stated it looks only afected a particular roll: the white PLA, I have tested the other rolls in the last days, none of them seems to have been afected

Silica gel works down to about 30% RH. CaCl2 works better and is very cheap, especially if you live in a cold winter climate- it's the stuff they sell in 50 lb bags for deicing sidewalks when the temperature is below 0 F. You can also buy it prepackaged in a disposable container as "Damp-Rid". The stuff absorbs so much moisture that it becomes mud eventually which is how you know when to replace it.

See: [www.absortech.jp]

---

Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Where do you get this Calcium Chloride from? I just googled and got 0 shopping results in Australia.
Its probably a restricted substance here, along with a ton of other harmless things. Meanwhile calcium hypochlorite and brake fluid can be obtained together, in bulk, at some hardwares without the batting of a single eyelash... Facepalm...

I wonder if anyone has tried lime? The mineral, not the fruit. The fruit may make your prints smell nice though.

Look for anything intended to prevent dampness in closets, etc. In the US the stuff is called Damp-Rid. [www.damprid.com]

CaCl2 is the second most abundant compound (next to NaCl) in sea water. It's some of the most common stuff on the planet...

---

Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

When you dry with temperature you make two things:

- Remove water (obvious)
- Crystallize the polymer

These two bring a plastic with higher resistance to flow. Water acts as a plasticizer and you have to melt the new crystals to get flow.

Edited 1 time(s). Last edit at 09/14/2016 10:59AM by sliceheart.