I have a Sovol SV08 Max with enclosure. The enclosure has an exhaust fan and an intake fan, controllable seperately.
I’ve printed PLA with the door open, and ABS with it shut so far.
When would I actually use the exhaust/intake fans? And is there any occurrence where I would need to control them independently?
I ask because I’m wondering if I can rewire them to the same port and use the additional line for a Nevermore filter fan.
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Exhaust/intake fans generally aren’t too important - materials like PLA that tolerate the air in the printer being replaced have very low emissions of potentially harmful VOCs and particles, and materials like ABS that emit lots of nasty stuff want the chamber air to stay hot, so having a fan replace the hot air with cold air isn’t great.
If you do have nasty stuff in the printer chamber that you want to send out a window, then the exhaust fan is the more important one. Unless your chamber is totally sealed, an intake fan is going to increase the chamber pressure and encourage contaminated air to go out any gaps, whereas an exhaust fan makes the pressure lower inside the chamber, so encourages clean air to come in through the gaps, stopping contamination escaping. Obviously, this is only relevant if you’ve got a vent tube or filter on the extractor, as if it’s just extracting into the room, there’s no difference between it extracting the air and it leaking.
I guess maybe the use case for an intake fan is either if you’ve got a material that wants the coldest air possible, so want to swap the chamber air for outside air as quickly as you can, or if you’ve got the exhaust fan venting into a chamber where you’re filtering the air without letting it cool down much, and the intake draws from that chamber. I don’t think either of these are particularly common situations, though.
I’ve got a non-max SV08, and I just don’t have an extractor or intake fan on my enclosure, and feed the extractor fan wire to my air filter.
If you’re going the route of a stealthmax, the v2 version has a servo controlled vent, original version it’s manual. All filaments give off material you don’t want to breath, nevermore has good info on this in the micro repo. Personally, I’d always aim for enclosed no matter what, the most I have in my garage is a box fan w/ decent furnace filters taped to it (works for wildfire smoke), I’d be venting outside if I had to setup inside the house.
I only ever had filtered recirc and exhaust on my enclosures, I’d rather keep it slightly negative to ambient air to try keeping the atmosphere inside the printer.
It’s worth bearing in mind that those bar charts on the Nevermore repo are showing the ratio of VOCs rather than the quantity, so make particularly nasty materials like ABS appear comparable to much safer ones like PLA. It’s not going to do you any good if you melt several kilos of PLA in a pan then take the lid off and huff the fumes, but running a single 3D printer with PLA in a large room is going to be pretty safe. The main VOCs emitted by PLA aren’t that harmful - some like acetone and acetaldehyde are produced by the human body and found in food (athough turning alcohol to acetaldehyde is what causes hangovers), methyl methacrylate is used to glue in hip replacements, and isobutanol is often a fermentation byproduct that ends up in alcoholic drinks. That doesn’t mean that PLA fumes are completely harmless, but means that it’s not worth worrying about the level of harm as running a printer in a room with the door open for a whole day is probably somewhere around the level of harm as eating cooked food or having a small beer.
