Source
r/3Dprinting•
killane

Question about air return

Discussion

I'm working on an enclosure for my Monoprice Maker Select v2 (the well-known rebranded Wanhao i3) using 3 stacked Lack tables from Ikea and some acrylic windows. My issue is that my wife is horribly allergic to corn, so when I want to print PLA, I have to close the printer and enclosure in another room until the air is clear enough that she won't get an allergic reaction.

So, I'm looking into making this and mounting it on a small thermal exhaust port in the bottom of the enclosure. After adjusting for tiny, one-man fighters potentially shooting torpedos into the exhaust port, I realized that having the enclosure entirely closed and sealed to keep any vaporized PLA inside for filtering, I'm going to have an ambient temperature issue. So I was looking at setting an ambient air return into the top of the enclosure using a floor register from home depot, potentially with an inline HEPA filter in it since the scrubber creates a negative pressure in the enclosure, this should make it so I can leave the register open when doing PLA and get no vaporization and I won't have to worry about the ambient temperature reaching the glass transition point, then I can close it for ABS and keep the stink in.

What I'm wondering is, does this all seem like it will work to keep PLA out of the air without ruining all of my prints?

Posted Oct 7, 2016, 4:29 PM UTC

725
PuffThePedWanhaoI3 LittleRP GiantDelta•

Why not just switch to PET or PETG? It's almost as easy to print as PLA, doesn't need an enclosure, no corn.

7
killaneOP•

I'm new to this and hadn't researched PET or PETG, I shall now learn more!

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PuffThePedWanhaoI3 LittleRP GiantDelta•

There are many more, you are not limited to PLA. Good luck!

1
overzeetop•

Yup - try ABS. If you're building an enclosure already that will be perfect as the hotter temps required do better when the unit is enclosed. As a bonus, it's much more impact resistant than pla. I have tried PETG - I'd like to switch to it, actually - but it was harder to dial in than ABS so I just went with ABS. Ultimately I'd like to print nylon, but it can get a bit pricey. (I have a Maker Select, too, FWIW)

1
RememberToBackupDataAUS. Printrbot Simple, unheated bed. Blue tape is forever! <3•

If OP is having a problem with PLA fumes, then perhaps ABS fumes will not be much better, though.

1
overzeetop•

Except that PLA is a corn product, and it's a corn allergy that is the issue. ABS particulate may also be an issue, but it wouldn't be a result of the corn sensitivity. PETG is probably the best solution - it's just a pain to dial in, in my experience.

3
TomvdZ•

It seems very, very, very unlikely that you wife could possibly have an allergic reaction to PLA. There's heavy chemical processing to make PLA from corn starch, and the molecular structure is changed completely in this process. You might want to consult your doctor to see if this is really an issue for your wife.

PLA is also commonly used in disposable cutlery and plastic cups, so unless you religiously check those items for being made of PLA or not, she's probably used PLA cutlerly before.

http://www.greenworld365.com/what-are-corn-starch-biocompostables-aka-pla-plastics/

Corn allergies are not an issue since the allergen, profilin, is destroyed in the manufacturing process.

3
killaneOP•

Thanks, I won't worry so much about it. I wish I had a couple extra lifetimes to do more study in materials sciences and things like that.

2
hellphish•

Do people with a corn allergy react to PLA fumes? Is this a known fact or is it something you are just being extra cautious about?

1
killaneOP•

Being extra cautious as she's presently pregnant and I understand breathing is an important part of pregnancies.

She reacts to a lot of things that are derived from corn as well, like maltodextrin and baking powder, so I just want to make sure I'm not going to be making her breathe what are, to her, toxic fumes.

5
Ressotami•

You're going about it all wrong. From an engineering perspective it's less efficient to filter the printer.

You need to be filtering the wife

5
killaneOP•

Interestingly, I have a gas mask sitting around as I got one of the President Trump Bug-Out Bags from Card Against Humanity and it included one. I haven't checked the rating on the filters though and she's claustrophobic so I don't think I could get her to wear it.

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TheInnocentEyeRostock Max V2•

What kind of ambient temperature issue are you going to have? I've never had reason to think of running a warm enclosure for PLA as a bad thing.

1
killaneOP•

I was concerned about the ambient temp getting close to the glass transition point on long prints, but as KevMag says, that shouldn't be a problem. I'm getting the impression that regardless; I won't need a cold air return, and I should invest in some PETG for learning.

1
KevMag•

Excessive heat should not be a problem. When printing ABS in a completely sealed enclosure with a 100C bed and 250C hotend my temp never exceeds 35C (22C ambient).

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LegitimateWorkUser•

I don't think a HEPA will filter out any fumes. They're just for particles.

1
killaneOP•

Okay, I'll research more filters if I decide to take this approach

1
LegitimateWorkUser•

Perhaps a gask mask canister from the army surplus store. They should have adequate flow, and don't cost much.

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killaneOP•

that sounds like a good option.

1
Golluk•

I'm making something very similar. Same printer, same Lack stands.

What I'm thinking of trying, is a combination of exhaust and recirculate. A fan will suck enclosure air through a P100, and VOC gas mask filter. Most of it will get blown back into the enclosure, but some will be diverted outside. My aim is to keep a slight negative pressure in the enclosure, while mostly letting it warm up.

Should have the filters by next week, then I'll start working out a mount for them.

1
GarageDIY•

I am guessing you have access to a window or two.

I am thinking that I am going to setup a ventilation system for 3d printers with enclosures for perhaps similar reasons. Look for inline vent fans, flexible duct hose and vent dampers to get a general idea. From there all you'd need is something like rigid foam insulation to place over the window and cut a hole through for the ventilation exhaust.

Some vent dampers are manual, some are closed with the lack of pressure and open when there is pressure (fan turns on). One vent damper as the inlet and one as the outlet would probably do a pretty good job of keeping things pretty well in the box, but I imagine if it was needed you could fashion something that you can open and close similar to how you might open or close the top to a grill or something. Even just a lid that you can open and close fairly easily would probably help prevent anything from escaping the inlet.

I am skeptical any indoor filtration system will do a really good job for this, or at least come anywhere close to matching a exhaust ventilation setup.

A box fan with a 20x20 filter over it might help plenty just moving air around the room, vastly better than that thingiverse item you linked to, if anything you could consider both if exhaust ventilation is absolutely not an option.

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