Printing in hot and humid environments (wet summer weather)  

RE: Printing in hot and humid environments (wet summer weather)

Make sure the air flow in the drybox has inlet and outlet - you want the air to be flowing through the bix, not just the outlet because it will be not enough air going through. 

Try to dry it on the max temperature, the device says it can reach 70C but in practice it may be much lower inside - you could try to test it with some thermometer to see what's the temperature on the top. For anything except those easy melting filaments (such as PLA) i would stick to max temperature that box offers, which is 70C - because evey extra 5C really improves drying and shortens time to do it.

When drying usually it is best to dry it multiple times because the air will not go through to the deeper layers of the spool, so for example it is better to start drying before the print say 4h and then start printing and drying in the same time or activate drying every 1/4 spool printed - it yelds the best results.

Remember that if you dry with the filament mounted in the printer then that fragment between the drybox and the nozzle will not dry and will have noticeable issues - unload the filament, attach it to the spool and dry it, or just cut that part and use for some maintenance tasks auch as cold pull or first layer calibration on the prints where you can have ugly walls ( gridfinity boxes? ).

I recommend to install PTFE tube between the drybox and the enclosure and the printer  - it helps in extreme moisture conditions, also helps to minimize amount of dust getting on to the filament which can over time accumulate and cause print imperfections ( though it is also advisable to put a cleaning sponge clip on the filament).

If you don't print immediately you can just put the filament in the dryer and dry it and then put it in the plastic vacuum bags with the silicate, and store it - this way you wont need to dry that much in the future or drying will be just faster. people do it because sometimes they don't have time to pre-dry the filament or need to swap to another material, so it minimizes time when the printer is not printing.

RE: Printing in hot and humid environments (wet summer weather)

I am on an island in the south of Sweden, water all around there are no dry days except in the winter if the sea freezes. I take care not to leave any filament out in the open and remove it from the printer between prints storing it in vacuum bags, I printed silica containers for the spool center and leave them in the bag while storing and in the dryer while printing. I have the same creality pi 2 dryer and it seems to do a decent job of keeping moisture away during printing. Maybe a difference is that I have an enclosed core one but I have not had any problems yet. I am new at this so it will happen eventually. I have a convenient gap in the pfte tube but only a few cm so that I can grab the filament for inserting and removing.

RE: Printing in hot and humid environments (wet summer weather)

I also print in a place that is very humid in the summer time, and with the Mini, so maybe I can offer a perspective.

Looking at the pics, there is definitely something going on with this filament. However, it may not be what you think. In order, I would investigate:

* Dryness of filament. I see that you followed the drying instructions, but are you sure that your drying method is doing what you think it is ? Transporting the filament shouldn't be enough to increase moisture absorption. Even at high ambient humidity, you should be able to get good performance from a thoroughly dried filament for 6-8 hours or so.  Instead of drying the whole spool, try drying maybe 50grams or so, and printing a small test object.

* Ambient temperature in the enclosure. Running a Mini in an unairconditioned room, in an enclosure, in the summer, with the print bed at recommended temperatures can quickly raise the surrounding temperature above what is optimal for the material. I find that performance of PETG starts to degrade at ambient temperatures greater than 30C. Can you put a small thermometer in the chamber to monitor the temperature as you print ?

* Nozzle temperature too low / too high for the filament.  Another issue related to temperature and print performance is, of course, nozzle temperature. If your filament is dry, and your enclosure stays at or below 30C, you may want to try to print a temperature tower ( https://www.printables.com/model/783622-temperature-tower) to see where you start to get performance degradation with the filament. 

* Clogging. You may also have one or more mechanical issues that are contributing to the performance issue shown. A clog can cause blobbing and / or stringing (typically, what you would see would look like underextrusion, but you can also get filament buildup and then blobbing as the nozzle rakes across the strings). This probably isn't it, but just for fun, try a cold pull with a contrasting filament color (I'd do this 3-4 times) to see if you get anything out. ( https://help.prusa3d.com/article/clogged-nozzle-hotend-mini-mini_112011)  

* Dirty drive gears. Another (probably more esoteric) problem that could cause under or over extrusion, and odd print artifacts. If your idler screw is too tight, it could grind / strip the filament on the way to the extruder, leading to an inconsistent filament diameter, and slipping of the filament in the drive gear. This is easy to check - just open the door on top of the drive gear and check to see if you have filament shreds. 

I'd probably go through these steps before expanding my setup to further combat humidity. If all else fails, and the environment is really impossible, a window A/C set to "dry" in a closed room can help lower the ambient humidity by 10 - 15% points. 

Good luck!