Using food ovens for drying filament
I have several high-temp filaments (PET-CF, PA-CF, etc.) that are really difficult or near impossible to dry in regular filament dryers due to their max temperature being too low. However, I have a countertop electric convection oven that can easily do these temps. Thing is, I use it for food, and I am afraid these filaments might contaminate these ovens and I could poison myself if I cook food in them afterwards. I know for example that doing with ABS would be outright deadly. However, some other filaments might be benign and okay to dry in food ovens because they don't outgas anything dangerous.
However, since I'm not sure about it and I can't find any definitive info, I am thinking of maybe I could construct some kind of box with a membrane that allows moisture out, but blocks any volatile compounds from escaping into the oven? Something like the 3M particle/vapor filters used on respirators? I am not entirely sure if they would block anything dangerous and also let moisture out of the box.
Or perhaps the box is not needed at all? Do PET-CF and PA-CF outgas anything that could contaminate food at 100-120°C?
I know it might be easy to say "just don't risk it, buy another oven", but I can't afford the space. And I exhausted all other options for drying filaments. So I'd rather find out for sure if this is dangerous or safe, or if it can be made safe. Looking forward to your comments!
RE: Using food ovens for drying filament
The 3M style filter all have one way valves that need a pressure differential to flow gas, they work on the basis of reduced pressure in the mask from breathing in allowing air in through the filter, then a separate unfiltered one way valve letting it out when you breath out. Therefore to get it to work you would need something to force air circulation. But as they are made out of cheap plastic (because they don't need to be any better) they would themselves melt.
RE: Using food ovens for drying filament
The 3M style filter all have one way valves that need a pressure differential to flow gas, they work on the basis of reduced pressure in the mask from breathing in allowing air in through the filter, then a separate unfiltered one way valve letting it out when you breath out. Therefore to get it to work you would need something to force air circulation. But as they are made out of cheap plastic (because they don't need to be any better) they would themselves melt.
Understood, that makes sense. While waiting for a reply, I found out that these temperatures are below the HDT of each of these plastics, and they don't outgas anything below HDT. So maybe that filter is not needed. However, it is still unclear if filler (CF) releases any particles into the air at these temperatures, and if they need/can be filtered somehow.
RE: Using food ovens for drying filament
"That’s an interesting idea! Using a food oven to dry filament could work if you can keep the temperature low and stable, but I’d be cautious since even a small spike could damage the material."
RE: Using food ovens for drying filament
"That’s an interesting idea! Using a food oven to dry filament could work if you can keep the temperature low and stable, but I’d be cautious since even a small spike could damage the material."
You don't have to use quotes when pasting ChatGPT replies. 🙄
RE: Using food ovens for drying filament
Food oven temp controls generally have very poor PID performance and overshoots and undershoots are, well, not helpful for drying filament. Also, they lack air movement and exchange, you need to remove the moisture that come out of the filament; pretty sure presenting the filament with hot air at the same dewpoint as the base cold air won't dry it very well. Properly done, you dry ambient air, then heat it up to pass over the filament.
RE: Using food ovens for drying filament
"That’s an interesting idea! Using a food oven to dry filament could work if you can keep the temperature low and stable, but I’d be cautious since even a small spike could damage the material."
You don't have to use quotes when pasting ChatGPT replies. 🙄
It probably is ChatGPT. I’ve seen several AI accounts so far. I expect they are trying to get over the post limit so they can start spamming.
RE: Using food ovens for drying filament
Tim basically said it, I'll add some and make a little pro/con list:
pros
-you already have the oven
cons
-household ovens have wild temperature swings, in my experience +- 5°C-30°C around target temp - rather useless for filament
-cooking ovens are made to keep moisture in
-not very precise especially in the lower range (50°C-110°C)
-hot and cool spots (yes even in a convection oven)
-no filtering whatsoever
-wouldn't use for food any more if used for drying
Cooking ovens are made for heating, not drying, and due to pricing are not very precise. There are (cooking) ovens that could do it but they're much more expensive and can be found in the professional segment. At that price point you can buy at least one professional filament dryer though (if not 2-3).
RE: Using food ovens for drying filament
"Interesting post! I never thought about using food ovens for drying filament, but it makes sense as a controlled heat source. Definitely worth trying carefully to avoid overheating. Thanks for sharing!"