PSA for oven-drying filament

Just a warning for those who may need it - your oven may not keep temperatures as consistent as you might like if you try to dry your filament!

I was trying to troubleshoot some PETG issues (not an experienced printer, only got my P1S a couple weeks ago - so I’m trying a bit of everything) and read that I should be drying my PETG before use. 60 degrees for 6-8 hrs is what I’ve read so I fired up the oven. Lowest temp available was 150 degrees - that converts to about 65C so I figured I was fine. Popped the spool in and came back around 6h later to a deformed mess.

The filament doesn’t appear melted or deformed so I guess my next job is a re-spooler but it does make me wonder about the composition of the Bambu spools. I wish I had an accurate representation of the actual temp curve in the oven for those 7h (seems to be fine with cookies!).

Adding insult to injury - the spool weighed 1g less when it came out - I didn’t need to dry filament in the first place! Guess I’ll get some more filament and bump my nozzle temp (been using 255 so I’ll try 260-265).

Plenty of good info on PETG troubleshooting out there - just need to try the other steps to see which one will be magic.

So - don’t do what I done. Or don’t do it with my oven, at least :man_shrugging:t3:

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That’s a good PSA, as I have seen even Steffan on CNC Kitchen chuck his filaments into his own kitchen oven to dry them out. And the same for his desiccant.

Was it an ancient analog oven or one of the newer digital ones with convection built in?

Vision Miner sells metal spools to avoid this problem from happening to their high temperature filaments.

One does not necessarily need an oven to cause such a catostrophe.

This was my first attempt at pushing the DIY limits of bed drying. I had weeks of testing and a lot of great results at 70c. So I got a little cocky and decided, well… if 70c is good, 100c must be better…right?

This is what happens to regular plastic filament spool when in direct contact with a 100c bed for 8 hours.

BTW: This DIY setup proves that you don’t need an expensive drying machine, a $7 USB fan and filament box works just as well albeit much slower and you tie up your printer for a few hours. But if you’re heading to bed anyway, what difference does it make? Just remember that your spool may not tolerate the higher temps.

The key to any drying whether it’s oven or anything is to make sure air is always circulating or the spool is always moving so that hot spots don’t build up. The thing is, I know this fact by heart because my other hobby, system building, everyone knows to keep air flowing over hot components if you want to achieve high reliability and lessen component failure during overclocking. But did I listen to the little Angel​:angel: on my right shoulder? No… instead I listened to the Devil :smiling_imp: on my other shoulder that said… go ahead… what could go wrong? :bomb::exploding_head:

My second design borrowed from two different designs and I added a small fan with a downspout into a filament stand with air outlets. It didn’t need much to make 100c bed temps to work very well. All that was needed was that small stand to raise the spool off of direct contact with the bed and vent holes out the bottom for airflow to circulate inside the PETG hatbox.


While we’re sharing how to gain experience… I melted two spools of MakerBot PLA years ago in my kitchen oven - too high a temperature, with the spools directly on the metal rack. The result was two blobs of fused filament and twisted spools - trashed.

Your filament stand gadget is a good idea. It’s simple enough to sketch, but have you perhaps shared a (hopefully parametric STEP) file somewhere?

A box works well as insulation - as simple and effective as drying gets.

New-ish and fancy-ish. It’s digital and has convection but I didn’t use the convection - in retrospect, that may have helped even out the likely hotspot that created my issue. I agree with @Olias about keeping the air circulating and appreciate the project idea - might put that together or may just go food dehydrator method for speed…