Filament drying technique

I have begun experimenting with nylon, specifically Taulman Bridge. So far I have found mine to be pretty unusable out of the bag (factory sealed). It will even be mostly free from hissing and popping, but will warp up from the bed past a few mm high.
Drying in the oven works pretty well, I have been doing ~2hrs at maybe 120-130c and the warping is almost completely gone. Until the next day when the filament has picked back up moisture (despite a new silica pack in the ziplock). It also has the disadvantage of me cutting pieces of filament to dry, having short leftovers and being a pain to deal with without the spool.
In an ideal world I want to make a dryer that will dry filament as needed right from the spool. I'm trying to find recommended times and temps for drying this stuff or even times and temps that have worked for others so that I can design the process/dryer around that.
Also interested in hearing if anyone has used a vacuum pump to aid in getting the water out.

I can´t help you with the drying issue ( did you try Rice instead of silica gel?)

But for the short ends of filament, I have an idea to put them back together:
Take an extra hotend.
Replace the nozzle with a brass tube M6 outside/ 1.8mm inside. Heat it up and push two pieces of filament in it. They will melt and come out as one. ( after a bit of cooling )

This is just theory, I haven´t tested it yet. But it sounds doable?
-Olaf

Grab a sizable glass jar where an empty toilet paper roll can fit loosely. Dry the nylon in the oven, transferred to the roll, slide it inside the jar and fill it with rice and oven dryed sea salt (once filled you can remove the roll). Drill the lid of the jar and glue to the inside a sponge, push through the filament, close the lid tight and tape the piece of filament and hole. Once a month put the jar in the oven and warm it up for half an hour with the lid open and fill any voids with more rice and salt.

It is a tedious job, but it worth.

So I should use something that carries more moisture to reduce the moisture content of the filament?
As for a filament joiner I would make one were I to feel it was needed. Not interested in recovering a few cents of filament, just getting dry nylon to print.

As in my original post I'm looking for TIME and TEMP. I can appreciate if no one has this info or experience with his filament, but I'm not looking for storage or anything else just time and temps so I can figure the path length the filament needs in the oven.

Few degrees over boiling point, I use 225 Fahrenheit for 2 hours. The problem you will encounter is that the spool it comes in will deform and become useless, reason for the change in storage platform.

If you are measuring the filament and cutting it out, you might be able to reduce time to 30 minutes and increase temperature to 350 Fahrenheit. Can't give you an exact timing, but as long as the filament comes out of the oven clear like acrylic it's ready, any frosted looking means it still have humidity in it.

You are looking for the chicken with the golden egg. I don't think anyone here will give you an exact answer, everybody have their own method and procedures to dry and print with nylon.

Spools don't have to be plastic. Phenolic or metal will suffice.
I can (and will) do it the hard way, build, measure, test repeat, but a jumping off point would be nice. I'm also not sure you understand my end goal. It is a box (whatever shape and whatever is in it) that filament feeds in one side wet and out the other side dry. If I know how long filament takes at what temp I can plan how long the path should be. For instance if I'm broadly feeding 3 meters an hour into the printer and it takes a half hour to dry then he path should be a meter and a half. With a 30 min pre print heat I would be good to go. Nylon must be dried for molding and such, I wonder how that process is done.

You can measure the drying time by yourself. Buy a cheap high precision scale (0.01g precision over 100g or more, from $10 on ebay or aliexpress), which should be precise enough to get a graph of the 1% or 2% change of the total weight of the filament. Put 100g nylon filament in a very humid environment for some days. Weigh it, then put it in the oven and start drying it. Take it out of the oven every 10 minutes or so, and measure its weight again every time. When the weight stops decreasing, the filament is "dry" (meaning that you cannot make it drier than that).

You can do it for every drying temperature you want to test, and if you do it, posting the results online may be very useful for others too.

In my experience the words cheap and high precision (along with the equally important repeatability) are not found in the same sentence. To me personally if something is worth measuring, it's worth what the right tool to measure it costs. Henry Ford has a great saying about this. But I think it would be simpler to cut a bunch of several gram samples enough to print some test object, pull one every x minutes and test in the printer.

Nylon can sponge up moisture big time. PLA is just as notorious. I have a 25 gallon storage tub that has a sealed lid on it that I keep my filaments in. Inside is an open container of silica gel granules (about 1/2 kilo), and a humidity gauge. It consistently stays at about 25% inside. Since doing that, my moisture issues have subsided immensely.

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Koko76
In my experience the words cheap and high precision (along with the equally important repeatability) are not found in the same sentence. To me personally if something is worth measuring, it's worth what the right tool to measure it costs. Henry Ford has a great saying about this. But I think it would be simpler to cut a bunch of several gram samples enough to print some test object, pull one every x minutes and test in the printer.

The precision and accuracy claimed for those scales is ten times more than needed for the experiment. Ford's saying is great for sure, but useless without some math.

Take into account that the minimal drying time changes as a function of last days' humidity, how the filament is stored and a dozen other factors. So the drying time tested one day may not be suitable for the day after.

Again it's my personal experience. I could also say that I don't buy cheap Chinese measurement equipment. I buy good tools one time and don't worry about them. You can spend your money how you like. All I am looking for here are people with actual experience drying nylon. Not lectures on test methods or what tools are good enough for what.

My last post on the thread, I do not want to pollute it uselessly.

I wish there was such a filament drying expert, not only for nylon, and I wish you the best luck in finding him/her. From what I see, every reprapper has his/her own recipe which works for him/her and may not work for others. So if such an expert does not show up (since he/she probably does not exist), you will have to find your own recipe which will work for you and maybe not for others. It would be great if from time to time some reprapper produced data that work for everybody (that is, become the expert!) but I see it is not the case here.

I have never tested filament drying, but I made several tests on filament storage and I can tell that a small silica bag in a plastic bag has the same effect on keeping a filament dry than a holy picture. On the other hand ggherbaz's storing method looks smart and much easier than drying the filament on the fly. Many thanks ggherbaz for sharing it.

Edited 1 time(s). Last edit at 06/03/2015 07:38PM by cristian.

Preheat oven to 300℃ for 25minutes.
Place spool in for 55 Minutes. Easy...

I'm kidding.

I keep mine dry by putting in garbage bag with a huge silaca gel bag. I can just stack on shelf.

I wad going to use a big plastic box.
with some rice in the bottom. The rice would soak moisture.

2hours are a bit short. I leave bridge for about 4 at 70c. After use i put it in an airtight container. The bottom of that container i filled with about half a kilo of silica gel (kitty litter). So far the best solution i found.

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Werner Berry has a video on YouTube of his dryer/storage setup, which uses a vacuum pump and a $99 Harbor Freight (USA) paint sprayer pot. I've also read posts about people using food dehydrators to dry filament with good luck. I have wondered what would happen to a spool of wet filament if left on my heated bed for several hours at 110C with a cardboard box over it, but never tested it.....

After thinking for a while, Olaf idea of joining the filaments might work better as a pre-dryer for nylon. Using a copper coil after it to cool down enough the filament before it gets to the extruder which will be pulling the filament though the heated barrel. In theory all moisture will be steamed out with the first "extrusion".

I will definitely play with this idea.

I had problem with humedity. After a lot of research and thinking, I came to this: [forums.reprap.org] (see in the middle of post)
My dryer lets me dry many rolls at the time and also print with the roll inside, so it is always dry.
Regarding times, I had problem with hig temepratures: for some reason some filaments change something in their composition. Also, the roll itself sometimed deforms. Better results for any kind of filaments: 4/5 hs at 40 degrees. The gives me a really nice dry filaments,
Hope it helps

I bought a 5 gallon bucket from the hardware store that comes with a gasketed / threaded lid. I also purchased 3 pounds of dessicant from amazon and threw it inside. put your spools in the bucket and keep it sealed up when storing filament. I've been storing 5 lbs of filament of all types for over a year and still havent had to recharge the silica beads. if you happen to leave a spool out for too long, just throw it in the bucket with the rest and it will be dried out in a couple of days. Total cost - around 15 bucks.

I have no experience with nylon, Is it even worth all this effort? sounds like its a huge headache to deal with

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Yes. It is.

Well I am using an AIR TIGHT CONTAINER with SILICA GEL in it to Keep Filaments Dry and moisture Free.

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dtwrv6
Yes. It is.

X2

Great for functional parts, crazy strong and hard-wearing. Has quite a bit of flex so for some purposes may need some form of insert to provide stiffness. One of the main use cases I had in mind for dual extruders was being able to print carbon-fibre abs stiffeners inside nylon parts.

The surface finish with nylon can also be really nice, so you could use it for decorative prints, if cost isn't a concern. Nylon is probably my favorite filament, except for price and the fairly major warping you have to deal with.

if you are going to go trough the headache of nylon, why not go for nylon trimmer line? its really cheap in bulk and doubt its that much more of a pain if you are already going the distance.

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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

Quote
Tinchus
I had problem with humedity. After a lot of research and thinking, I came to this: [forums.reprap.org] (see in the middle of post)
My dryer lets me dry many rolls at the time and also print with the roll inside, so it is always dry.
Regarding times, I had problem with hig temepratures: for some reason some filaments change something in their composition. Also, the roll itself sometimed deforms. Better results for any kind of filaments: 4/5 hs at 40 degrees. The gives me a really nice dry filaments,
Hope it helps

I have just ordered the same TEC driver shown in the forums post link above. I'm in the process of building a dryer, which has an air tight lid and pulls it's air into a cold environment so that the moisture drops out of it, thus drying the air with no heat, only warm air at a controlled temperature.

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