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latigerlilly

Air Purifier for 3d Printers

by latigerlilly May 22, 2014
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So just to be sure.

Put the fan on the bottom if this print and then place the carbon directly on the grill? or place mask down like your other post?

I don't understand this design.
It looks like it is not the same as the one with the red line.
Where is the carbon placed ?
Is it mounted completely mounted inside the enclosure?

Yes, any 40 mm fan would work. I use a laboratory grade 13.8V 6-8Amp DC power supply attached to a 12V 40mm fan, but any 40mm fan connected to a matching voltage power supply with greater than the rated amps on the fan x3 for surge voltage would work. I print it at 10% fill so it barely weighs anything at all. The plastic printed part weighs about 20g, give or take a couple grams depending on your fill ratio, flow rate, and other calibrations. The fan's weight depends on the particular fan used but most weigh about 18g. The activated carbon granules degrade over time and use. I would recommend replacing the granules every month or every printer maintenance cycle, whichever comes first. A printer maintenance cycle for a FDM 3d printer would include lubricating the rods, lubricating the fan's bearings, cleaning plastic bits off the extruder drive gears, and replacing the kapton tape.

i'm sorry.. I was unclear.
I meant to say perhaps such a filter box could be attached to an existing, operative fan already in use.
For instance on my printer the 40mm extruder heatsink cooling fan has plenty of room for a box. It currently holds only a small fan guard. Many people have some sort of fan-shroud installed on one side of their extruder fans while the outboard side is wide open and available.
But perhaps the additional flow resistance due to a filter element might not allow the heat sink to cool properly. Or it might impede whatever other job a existing fan is expected to do.
However, it sure would be a lot simpler to incorporate a recirculating air filter if it didn't require an additional fan plus its power supply.

No, the airflow through the carbon filtration media is s-l-o-w. If you attach the filter to the heat sink fan for the nozzle or motherboard cooling fan, you'd probably damage your 3d printer. In fact the airflow is so poor that you cannot feel the airflow at all. I had to verify the airflow with a candle flame. That's why I specified 10-12 mm of filtration media only, maximum, because I've experimented and if you use more activated carbon filtration media, you will get zero airflow.

guess I gotta d/load the file and see what it looks like...
I bought a very similar box (Aqua-tech) of activated carbon from the pet store but it is unopened at this time.
OK.. It's just blowing upwards through a loose layer of granules. Plenty of venting. Seems like air resistance would be minimal or close to it with this configuration.
Question. Assuming you haven't yet tested air quality after the filter has run for some set amount of time, why did you settle on the 10-12 mm layer?
My thinking is a much thinner layer might clean the air better and/or faster since air flow would increase. Recirculation affords as many passes as might be required..
But I have no idea how activated carbon's remaining adsorption capacity nor air quality can be accurately measured, and therefore how different systems can be compared.
I suspect some rather sophisticated lab equipment would be needed.

Your Aqua-Tech should work fine. My experiments are actually with the Aqua-Tech activated carbon granules.
Per my previous post, if it is more than 10-12 mm of activated carbon granules then there is no detectable airflow. I used a candle flame to detect airflow.
"sophisticated lab equipment." LOL. You must work for a very well funded government lab funded by a bottomless pit of tax dollars. I wish I work in your lab. No, my lab is privately funded by my paychecks, so some creative workarounds are often used instead of lost o' money. In our case, there are 2 reasons why we want to use this air filter; for 1. pleasant odor and 2. safety. Reason 1. doesn't need "sophisticated lab equipment". It only needs my nose. Reason 2. is a bit more complex. The toxic gases produced in ABS 3d printing include; phenols, nitrogen oxide, hydrogen bromide, carbon monoxide, hydrogen cyanide, and styrene. Of these gases, hydrogen cyanide (HCN), is the most immediately toxic. Although Taulmanhttp://www.instructables.com/i... has determined normal 3d printing to be safe, what about abnormal printing such as printer jams and defective filament? About 60 percent of the population can smell cyanide. It smells like bitter almonds. Make friends with a chemistry professor and tell him what a big sexy brain he/she has. Get permission to use the prof's lab to make a 4.7 ppm HCN solution in a properly rated biological safety cabinet. See if you can smell the HCN. If you can then, congrats! You are in the lucky 60 percent with the HCN smelling gene. Therefore, if you don't smell any evil with my set up, then it is probably protecting you from evil.
Please note that this is a 3d print of an EXPERIMENTAL DEVICE. Use at your own risk. Do all your own experimentation before determining if this is the right set up for YOU. You may need to alter the set up because it is EXPERIMENTAL. I therefore, provide no warranty of merchantability, safety, nor utility. Use at your own risk.
References: MSDShttp://www.plasticsmadesimple....
Taulmanhttp://www.instructables.com/i...
PEL HCNhttp://www.raesystems.com/site...
Efficacy of Activated Carbon Fume Adsorptionhttp://www.salareinc.com/pdf/F...

Speaking of well funded labs, NASA has been messing with printers and testing them for at least 3 years but has yet to get one up in the space station. All the stress-test type stuff has been approved but I think they are still working out a few bugs in the filtering and enclosure systems.
Perhaps one way to combine a filter with an existing fan would be to switch from these weak axial fans to a centrifugal blower. They develop significant pressure. Granules would be everywhere. A more appropriate filter might be a piece of any existing activated carbon air filter element.

Filters in space demand a totally different set of demands than ones on earth. There is ZERO room for error in space. All components and instrumentation are critical because everything is accounted for down to the smallest gram due to mission weight constraints. Any fans with moving parts are parts that may break and WILL take away valuable astronaut's time to fix. Any fan, centrifugal or axial will need service and may break due to their use of moving parts. If I were to design an air filter for NASA, I would make an electrostatic air impeller much like those air filters that Sharper Image were selling before they went bankrupt. Those things have a near 100 percent reliability due to a lack of moving parts that can break. However, the design would have to be improved to decrease power consumption and increase air pressure. The 3d printer should also be DLP to avoid any moving parts. However, DLP deals with liquids, which are problematic for a zero gravity environment. Artificial gravity that is stable will have to be created.

ah yes... Sharper Image's Ionic Breeze.... You'd think a company with retail outlets in malls across the nation could easily afford half a million $ in court costs, but evidently not.
I've played with corona discharge air movers. It's an intriguing fan-less solution to maintenance.problems.... but one downside is they create quite a bit of ozone and I doubt NASA.wants much of such a powerful oxidizer in the atmosphere.
The electrostatic precipitators I am aware of do use fans to move the air past the electrodes. And they are not able to charge gas molecules, only particulates like mists and dust. So rather than capture and remove hydrogen cyanide, nitrogen oxides, etc we'd probably end up with a very "clean" but still poisonous environment.
As for DLP printers, the last I heard NASA intended on sending regular old filament printers, including a couple of UP!s. Afaik those are the ones they examined in the roughly 400 microgravity (parabolic flight) testing phase. I guess they wanted to see if they can print when upside down?

i suppose such a a box might be attached to any already existing fan... as long as it's running whenever printing, is match-sized for the filter box, and if space is adequate. How much does the assembly weigh?
Have you determined how long a carbon element remains effective?