Fume-blocking Enclosure

[bicx]

Hello MakerGear community!

First time posting here. Just wanted to share the enclosure I built for my printer. After moving into a new house with less ventilation for 3d printing, I wanted to build an enclosure system that focused on reducing fumes/odors/microparticles in my living quarters. First, I needed to ensure the enclosure was as well-sealed as possible. Secondly, I wanted to build in an active filtration system to reduce the amount of noticeable fume buildup within the enclosure.

My enclosure is pretty basic. It's a box made of 1/2" birch plywood, primed with Kilz odor-blocking primer and spray-painted white on the interior. An inner frame along the opening provides contact area for the rubber seal strips (functioning as a gasket of sorts) that come into contact with the inner frame of the door. The door is detachable and is held tight against the inner seal via toolbox-style spring-tensioned latches to ensure a decent seal. I'm not sure if I'm crazy about the detachable door design, but it's also a large door to have swinging around in a smaller space like my office.



Next was the filter. After doing a little research, I learned that I needed to combine carbon filtration with HEPA to tackle both odors and microparticles. I found a design I liked a lot here, and I adapted it into a basic design I could include in modular form inside the enclosure. The end product was maybe one of the uglier things I've built, but it seems to function so far.



Full Imgur album here with some build progress shots and other notes

I've yet to test all this together, but I'm hoping tonight will be my first successful test run. This is one of my first woodworking projects, and I think it turned out pretty well.

[Farr0wn3d]

I'm currently building an enclosure as well. My filtration was going to be single pass, with an arduino to modulate the fans pushing air into the enclosure with the filter situated at the top where the air vents out. My logic here was to keep the temp of the enclosure regulated, assuming that it could possibly get too hot in there.

I'm curious to know how yours performs with no cooling and recirculating filtration. do you plan on monitoring the temperature of the enclosure at all? if so I would be interested to know how hot it gets.

[bicx]

So after some discussion with others, I realized that even with a HEPA filter, I couldn't effectively filter out the ultra fine particles that are the more dangerous at high concentrations. HEPA filters particles down to 300nm, but the ultrafine particles generated by printing in ABS and PLA can less than 100nm. The HEPA filter may be a nice-to-have, but it won't solve the issue by itself. I'm back to considering some sort of airflow system that you mentioned above.

I've only done a couple small prints so far, but I haven't noticed a significant heat buildup. I don't think that will be my issue, at least for now.

With the problem of varying temperature in air currents, I've been brainstorming on how to keep everything regulated as you said. I heard of an idea from another forum where a hair dryer is hooked to a temperature-monitoring arduino and switched between heating and cooling depending on a set temp. Seems like maybe overkill, but fun to build.

[Farr0wn3d]

After further consideration, I've decided to make mine a recirculating filtration setup, and just try to filter the air inside the case as much as possible. I'm thinking that if there are UFP's being emitted, that I'm probably better off keeping them contained within the enclosure for long prints, rather than venting them into my home intentionally. I have an idea for a heat exchanger that I'm going to use to help regulate the heat inside the case. I generally print with the bed at 80, so I'm assuming that the enclosure will easily reach 80 or higher and the motors arent rated for that AFAIK. I've also designed stepper motor fan ducts, in case anyone would like the file. they take a standard 40mm fan.

[ednisley]

the motors arent rated for that

The RAMBo board will be the weaker link: it has marginal heatsinking for the power FETs and terrible airflow around all the wires in the electronics case. Run plenty of cooling air (at room ambient) over the board and, if you need a source of cool air in the printer enclosure, vent it there instead of back into the room.

[Farr0wn3d]

Thanks for chiming in Ed. Unfortunately its not very realistic for me to give the rambo fresh air, but would it be acceptable to get some of those mini heatsinks for stepper drivers and raspberry pies and place then on the drivers and MOSFET's, and then upgrade the fan in the electronics case, and have the enclosure at about 40-50C?

BICX, in your opinion, are the 2 blowers necessary? or could the job be done by one blower? Do you know the output ratings on your blower motors?

[ednisley]

some of those mini heatsinks

Those are largely cosmetic: they're glued to the FET's epoxy package, which is a pretty good insulator even without adding two layers of goo and more plastic. The main heat path from the die goes through the metal tab on the bottom that's soldered to the PCB; the problem is that the PCB is a crappy heatsink that doesn't get much airflow.

So the FET heatsinking is marginal, even in room temperature air and elevating the air by 20 ⁰C isn't going to do it the least little bit of good. Increasing the airflow doesn't help much, because you're blowing hot air over a hot board and the FETs get that much hotter. What matters is keeping the board cool enough that the FETs &c don't overheat, which requires more room-temperature airflow.

There's also a bit of heat generated in the other components. Stick your finger in there some time and feel around for the hot spots.

It'll probably work for quite a while, but should it fail, you get to buy a new RAMBo. That's the pessimistic view, anyhow.

are the 2 blowers necessary

I have an ancient M2 with a single fan in the middle of the top of the box that I replaced with a 24 V fan when I hacked up the power supplies.

If the new M2s sport two fans on the electronics box, well, then I rest my case about marginal cooling; you have all the evidence you need that more cool air is better ...

[Farr0wn3d]

The 2 blowers was in reference to the filtration enclosure.

[ednisley]

reference to the filtration enclosure

I missed that transition.

An air-to-air heat exchanger that can transfer 200-ish W to ambient air will require a prodigious breeze. A casual search produced https://www.eicsolutions.com/product-ca ... xchangers/: if you want to keep the enclosure air at a reasonable temperature, you need a big exchanger with blowers both inside and outside of the box.

It seems to me that, if the filters can't extract the ultra-fines from the air (which is why you want a closed box), then the particles must accumulate in the air inside the box: when you open the door, out they come!

[Farr0wn3d]

Well, after further consideration, I will be returning the HEPA filter and activated carbon prefilter that I bought for this purpose and I'm going to get a ULPA filter instead. They capture down to 100 nanometers, so hopefully that will be adequate for my filtration needs.

Ed, with regard to needing a ton of flow to reject the heat produced inside the enclosure, I intend on having a lot of flow, including both the cooling air as well as the air to be cooled. I will be making an exchanger to test first before I make a functional unit for the enclosure.

I'm sure there are plenty of people who will have opinions about this project, but I'm far to interested in the challenge at this point to simply give up. I will start my own thread for this, so I dont hijack this one anymore.