Looking at filament dryers and thinking about the faff element. Really I want to just get on and print whenever I feel like it with whatever filament I want. So to have to dry filament for 8 hours before is not ideal. Drying and keeping them in a box with desiccant works up to a point but still isn’t ideal. So I thought why not a real time dryer. I thought I’d post on here for you learned types (i.e. not me) to shot holes in my idea. Using PLA. If a 1kg roll contains about 335m of filament and lets say you want to super dry it (excessively) so you stick it in the dryer for 10 hours. That means all things being equal it would take 2 minutes per meter roughly. If the max print speed is 3 meters per minute then a six meter route between the spool and the print head would mean a 2 minute per meter transition time. If this route was a pipe with 50 degrees dry air whizzing through then the filament could be wet one spool end and dry the other. I would guess you could probably halve that route and it would still be ok. The drying would actually be a lot more efficient as well as you wouldn’t be trying to dry through layers and can get 360 degree surface access and 10 hours is way over the top (normally). What do you think ? Am I way off ?
You’re attempting to birth a baby in one month by hiring nine mothers. I’m not sure the material process scales in that direction. While you 100% will get better and faster results due to pulling the spaghetti away from the spool and it gets full surface area contact, but i’m not sure it is capturing the full story of using heat to coerce vapor pressure evaporation of water in polymers. I’d be interested to see if you get condensate in your PTFE line post-dryer.
I think you will get good results simply from racking a spool of undry PLA in your dryer, pulling the noodle out and printing directly from the filament dryer. Your first 5 grams is in the PTFE lines and not drying, but after that it probably will be noticably improved, even only 15mins later. PLA is super forgiving. My instinct tells me this won’t help you for the truly hydroscopic spaghetti types out there, but you can try.
This is already a thing, it’s called inline filament dryer. They are very expensive (my first google hit was like €3000 which didn’t even include a needed(?) preheater for another €500).
There’s absolutely no reason you shouldn’t try to build one and please share your results!
Good analogy Bullocks, that made me laugh. @The_Raz the fact that there is a product out there regardless of cost indicates it is possible unless it is a complete scam and that is of course also possible. No matter how much money you throw at it there is only a few things you can fiddle with, Airflow, temp , pressure and air dryness. Maybe a slightly lower pressure than atmosphere whilst heating will get the filament to give up its treasures. A second section cooling it down to room temp should get rid of any chance of condensation in the PTFE lines… Alas though this printing stuff is fairly new to me I have the skills and the kit to build something like this just short of time at the moment. It’s on my to do list to give it a go at some point though. Last comment @Bullocks, statistically you have achieved an average of one baby per month…
I was curious about this and looked around in the product space for this. The dryer, not the babies.
This is NOT an endorsement or review, only for illustrative purposes
They seem to fill their “pipe” with dessicant, and use what appears to be guts from a hot-air-reflow-solder station thru it. Could be easy to DIY if you are so inclined, although I am sure there are details the untrained eye is missing 
It’s puzzling that none of the usual brands of consumer dryers (such as Sunlu) offer an inline alternative. Inline dryers are very interesting but they won’t help with wet PLA that (unintuitively) is so brittle it snaps in the AMS. Perhaps that’s why? Most consumers print almost exclusively PLA.
On a side note my interest for this vanished when I got the AMS2’s. Their drying feature is way more convenient than I had expected and the 85°C max. temp of the HT is better than all consumer driers I’ve seen on the market (I’m sure some can do better than 70°C but I never saw one).
Interesting. They say it reaches higher temp than others… Higher temp isn’t necessarily a good thing, the right temp is better. So if you heated it to say 400 degrees you’d have to whiz the filament through at a enhanced rate to stop it melting and any speed not matching the print speed would negate the purpose. I think it is a good idea to dry the air being heated and put through this thing so there maybe a place for Silica or better still a molecular sieve. However my view is if you maintain the right temp (i.e. as high as you can go without degrading the material) then length of time and surface area exposed is the key.
I agree you’d still have to store it sensibly or you’d never get it out of the AMS and through the dryer. Good point about the lack of inline units being produced by the big names in dryers , that is a bot telling as I’m sure it’s not because that haven’t thought of it and they have all they need to test and develop something that would be a game changers. This fact is probably the biggest indicator of it not working or at least it not being easy. I haven’t got a a fancy AMS2 but I can see how if you stick to up to four filaments for all your printing it would almost eliminate the problem for you. But still it wouldn’t handle a sudden desire to change to a colour or material not in the AMA.
I assumed it can reach higher temperatures, not that it always does. Surely there must be a setting so you can set it for eg. PLA without it melting. But now that you mentioned it, I’d be sure to verify this before buying one! 
Quite so, as reaching a higher temp is not necessarily a good thing or helpful to the process. Surely all will have the ability to reach the right temp ? Well for normal type filaments not some super high melting point stuff.