Mastodawn

Amy Qualls Jan 2

Heyo,
Me + @dx made a project for #39c3 this year, in which we made 5 DIY air purifiers a la Corsi-Rosenthal Cubes, but modified to be more portable, easier to take apart and put together, and overall be congress-safe. We had them at Angel Restaurant (2), CERT (2) and Kidspace (1), so you may have seen them around.

We have published details and files here if interested: https://github.com/c3infsch/aircycles (feel free to reach out with questions or if you want to build them so we can help)

We just finished taking them apart for the year and threw out most of the filters as they looked really dark, and with that we're done with 39c3 🎉

If you'd like to help offset our costs so far, and help us build more for future events (we got so many more requests than we could supply), we've set up donation links:
https://bunq.me/aveao (also shows the IBAN if you prefer to do a bank transfer)
https://paypal.me/aveaoz
(Transfer reference "Aircycles Donation" or "Aircycles Spende" please.)

As for the amount: We've spent about 700eur not including the costs of prototyping, and for next year we plan to build even more of them to meet the demand. We don't intend to make a profit, so I might edit this post later if donations reach too high an amount (but I doubt we'll get there).

Thank you! (and boosts welcome)

@dx For transparency: we got €245 so far! Thank you all very much, that'll be enough to run them again next year, and covers part of the costs we had so far.
We'll try to make 5 more by next year as well in general :)

@dx I just finished summing up the costs more or less, and it's ~112eur that we paid for each air purifier, for a total cost of ~563eur (excl. cost of filters, PETG, soldering supplies etc). With filters and PETG it'd be around ~157eur/ea. Of all that cost, only ~150eur will need to be spent again to make them usable next year, as the only part that we'll need to replace is filters.

And as for making more, I think we'll have some opportunities to lower costs next year as we won't need to spend so much on prototyping, and there's many leftover parts from bulk orders this year too.

So far we got ~269eur in donations, which covers almost half the cost we had out of pocket. Thank you so much!

@ave @dx I had spotted one of them at CERT. Cool to learn about the backgrounds :)

Alex Bissessur Jan 1

@ave Ooh, these are pretty cool and seem straightforward to setup. I might give it a try if I can get my hands on filters for not-too-much

@AlexB It's not suuper easy compared to something like https://github.com/timonsku/PC-Fan-MERV-Filter-Box as ours requires a large laser cutter, but I do think it is easy enough if you have access to one.
Someone is working on making an easier to make at home variant right now so fingers crossed!

GitHub - timonsku/PC-Fan-MERV-Filter-Box: A Corsi-Rosenthal style air filter using only 2 3M MERV filters and PC fans for a slimmer design.

A Corsi-Rosenthal style air filter using only 2 3M MERV filters and PC fans for a slimmer design. - timonsku/PC-Fan-MERV-Filter-Box

GitHub

Alex Bissessur Jan 2

@ave
Thank you a ton! I'll check out the other one though I might know someone with a laser cutter in their living room :P

@AlexB you need a very large laser cutter for it right now (tho ideas exist to make it into smaller parts), kudos to the person if they have one big enough in their living room :p
(that's a 62.5cm x 62.5cm square in there)

Alex Bissessur Jan 2

@ave If his isn't big enough, I think I saw a massive one at work. Cutting the wood isn't the hard part for me, I think I'd have more difficulties finding/shipping the filters

@ave @chillicampari @dx Whoa, trippy. Another dx.

@ave @dx And i was just doing research on easy to transport (DIY) air filters to use at the assemblies.
They look really good and good initiative!

@sa7dse @ave i'd love a more compact, possibly cylinder shaped design that people can just put in the middle of a table. there are consumer units like that, but i don't trust the performance of commercial air purifiers. i think we're gonna be doing a bunch of testing in the near future

@dx @ave i was looking at the box fan version and raise it off the table with some legs. So it blow air towards the table.
But they are fairly big and not easy to transport.

@dx @sa7dse @ave do you know the xiaomi air purifier filters? they are cylindrical and could be outfitted with a single fan in the middle and would be quite compact per surface area. aftermarket filters are also quite cheap at ~16€/pcs. but that would probably need some qualification as to how well the filters actually perform.

@ln @dx @sa7dse official ones appear to be hepa (and cost €40) which requires a lot more pressure to put things through than MERV 13, would be worried about quality of aftermarket ones tbh, but we can check.

part of the choice here is political as the ones we use are proven and widely used in this manner, and questions of "will this even work, you won't get any air through it, why not get something professional" etc etc are already commonplace (but currently easy to counter)

@ave @ln @dx @sa7dse and having standard filters that are easly sourced everywhere is quite nice too

@ave @dx @sa7dse i have the very strong urge to back this up with data now lol. i wanted to use a home-grown air purifier based on the cheap filters anyways and will report back if/when i make progress. hmm, now i wonder how to properly test and quantify this…

@ln @ave @sa7dse for measuring pm2.5 clean air delivery rate this is a cute guide: https://itsairborne.com/how-to-measure-hepa-air-cleaner-filter-cadr-a660bfa4479d

PM2.5 CADR is sliiightly differently defined to the cleanairkits target (dust CADR, 0.5-3μm) but the sensor we have (SPS30) considers the range 0.3-2.5μm so close enough

How to measure CADR of a HEPA air cleaner | It’s Airborne

How to measure the CADR Clean Air Delivery Rate of a HEPA air cleaner or Corsi-Rosenthal box using a PM2.5 meter and nebulizer DIY

It’s Airborne