What would be the best way to dry nylon filaments? I have used bambulab's PET-CF and quite impressed by its results. But I still have a lot of left over PA6 (two 2kg spools). One that is fully moist, prints turning out a bubbly mess, And another roll that is over extruding. I tried using a food dehydrator, but found the temperature quite low (75c). I am using a filament dryer for my current filaments, a Eibos Polyphemus (70c), works well but still low and not sufficiently dried.
Drying Filament. Options?
how long do you keep the rolls in the filament dryer?
Axlaser I kept the two kilogram roll (wet) in the dryer for at least a week. afterwards its was mildly dry (over extruding and still blobbing). The dry roll kept the same, with some parts of the roll getting thoroughly dry (black layer lines among the print).
LonisOvril Have you tried using an oven for slightly hotter drying temps? its not exactly the best and consistent for drying but it looks like you may need just a little more heat?? and also worth noting that if your filament is in a cardboard spool, the cardboard itself will hold some moisture, I would try the oven if you're comfortable with doing that, but other than that I'm not sure. I would also ask how long ago you bought it and how long its been in the open air roughly.
Axlaser I've used a Walmart toaster oven at temps at least at 100-150c, but the air inside isn't equal so I don't think I can dry it safely in the oven. both of the spools are in a cardboard spools. The wet spool was purchased back in July 2023, printed fine and was exposed to air for awhile. the other spool has been kept in a vacuum chamber every use. I feel like a lab oven would be a better choice for its more accurate temp readings and its convection heating.
Does your filament dryer show the humidity inside of the dryer? The one that I use shows the humidity on the screen. I did some digging around, and it seems that the wet PA6 filament may just be screwed? I know with pla plus/pro you can have them sitting there for months in storage (in a relatively ok humid environment) and they'll print just fine if you dry them a few hours before use, but I think with these carbon fiber nylon rolls, they seem to have a shelf life after prolonged exposure to moisture in the air. Correct me if I'm wrong, I just haven't had PA6 rolls sitting around for that long so I cant really help much more here, I'll tag @hoffmantactical here and see if he knows what to do, or what could be going on.
Axlaser From what I've seen, I would say it would, since it was only drying to a degree, but I also never went above 75c convection. My dryer does have a humidity senor on the front, that is always at 10% humidity. I contacted Polymaker about the spool and they gave me a coupon for a whole new spool, and what I've been storing to keep dry. It is dry, just not fully dry, it over extrudes, oozes and has a flat gray color to it.
LonisOvril 70 - 75 C (160 - 170 F) is enough to keep filament dry during printing, but I have found it to be too cool to dry already wet filament no matter how long it is dried for. This applies to Nylons and PET's.
185 F (85 C) is what I dry at with very good results. Unfortunately this is a bit hotter then commercial driers get (not sure why either, as it's both safe and easy to get a little hotter). I modified a Magic Mills drier by wiring the heater to always be on, and it runs at 185 F. You could do the same, or maybe use a toaster oven, assuming the oven has a convection fan to keep the inside temp even. You may have to do some hacking to get the oven cool enough.
Final point about some filaments being too far gone, I have observed this with Nylons that were left out for several years. Even with extensive drying they still have stringing and other water related issues. I don't know the cause of this on reversibility, but it only appears to be an issue after the Nylon was exposed to high humidity for a long time.
I've always used my conventional oven. It has a minimum temperature of 170 degrees F. I bought another thermometer to make sure the oven's reported temperature is correct.
Get the filament dry in the oven and use a filament drier to keep it dry during printing.