Drying plastic fail

so I may have made a major screw up but hoping I can fix it. I went to dry some PLA in a toaster oven had it turned down as low as it goes (about 70*C) and the roll melted together I can get a little off but then it is attached to good and snaps off would it work to heat it back off and then tried to role it onto another role as it cools?

I don’t see how you can keep the filament you’re pulling off acceptably round with a diameter of 1.75mm to use again.

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Yeah personally I would just write that roll off,

As sad as it is just chalk it up to a learning mistake and move on, as @mykepredko said it will loose its consistency pretty fast if that has happened.

As opposed to using a toaster oven you can actually dry filament using your printers heated bed. Lay the spool down on the heated bed, and set it to whatever temperature you need to dry it at. If you printer is enclosed just leave it for as long as it needs, if it is not enclosed you can cut the top off of a filament box and put the box overtop. This makes an enclosure just localised to the filament which will allow it to properly dry. If you use the filament box method add around another hour of drying time to the material to make sure that it has been properly dried.

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how long should I be leaving them and at what temperature should i set the bed?

Usually for PLA I will set the bed at around 45-50 ish, leave it for around 6 hours and give it a shot. If it is not good still throw it in for another hour.

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Huh, going to try this with an old roll right now!

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Let me know how it goes!

Here is a great demonstration of the process:

I first heard of this on another board some years ago, this guy does a good job at explaining and showing the process though, and there is also nothing really stopping you from drying multiple rolls at once if you have a bigger box, you might need to give it a bit longer though. Never tried drying more than one spool at once


does it make a difference if there is that little hole on the side or should I put some tape over it?

I would probably just tape over it, doesn’t have to be anything fancy. You just want to keep the warm air inside the box and stop it from escaping


I taped holes on the side of a box and cut a tiny hole at the top.
Bed at 70C for 6 hours on a spare printer.

Worked liked a charm, roll went from 425g to 419g and printed nicely :partying_face:

2-3 year old spool left in the open, 6 grams of water hiding in there!

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Good stuff!

I love how 3D printing is still at the point where there are lots of super janky solutions for problems

It would be interesting to know if an inexpensive filament dryer and a printer bed which one uses less power. It might be the DIY solution costs more in the long run.


That would be interesting to investigate.

I wonder about the efficiency of the processes as well, and if you get a larger box which could dry more than one spool how that would affect the efficiency of the process.

Hard to know which is the most efficient. The element in a filament dryer is very small. I don’t think it would be faster using a heat bed and a much larger heater. I would assume, bit. of an assumption is it would use more power.

I don’t actually know but it won’t work for the printers I have, they all would shut heating down far faster than the filament would dry. The time out is 30 mins maybe 45.

Curiosity however…

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I was making a long print yesterday and noticed my enclosure was sitting at 30C and 14% rh (I recognize how flaky RH is 15 gm/m3 absolute if you would rather)

I tucked a spool that is fairly damp in behind the printer for the whole 16 hour print time. It is noticeable less damp and prints better.

This might be a better option over running the printer to only dry filaments. It is just using the by product of making the print in the first place.

Hmm interesting,

Certainly if your print is long enough and you have the space to house the spool that will be more than enough, depending on what temperature your enclosure gets to you might just have to be careful with PLA.

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