Fume Filter

thingiverse

This is to eliminate the ABS fumes from a MakerBot or RepRap. I was tired of getting a (literal) headache from the ABS fumes off of Wintermute (my Cupcake CNC) and decided to make a filter. There are several other filters on Thingiverse, but they all seemed to be more concerned with removing the smell and less concerned with actually removing the VOCs that are along with the smell. I started with a PC-case fan and a HEPA filter with the carbon prefilter, but the fan just didn't have enough power. I tried the most powerful PC-case fan I could find. I ended up using a 12V DC bilge pump:http://www.amazon.com/gp/product/B001O0DE9E I'm using this HEPA filter from a vacuum cleaner:http://store.electroluxusa.com/el029.html It's about 50% more expensive than the other HEPA filters, but it's washable, which makes it worth it to me. It's also square, so it's easy to make a mount and seal for. Here is a video where I am testing it. (My wife says it looks like I'm sucking ghosts up into it. :) http://youtu.be/SN6HTDGGLfs?hd=1 The result of this experiment is intended to go with the fume hood by Built-to-Spec progress seen in this blog post:http://www.built-to-spec.com/blog/2011/03/08/progress-update-3810/ Instructions Buy the bilge pump, the filter, some cut-to-fit carbon prefilter, and some 3" "dryer vent" flexible hose. I got the prefilters in the "air filters" section of my local hardware store. You'll need a cardboard box to cut up. I used the one that the bilge pump came in. I also used some hobby sheet foam as a seal. (See the photos at http://www.flickr.com/photos/giseburt/sets/72157626175990569/ for some of this to make more sense.) Put the fan up against the end of the box and mark out the circle around it. Cut the circle a little bit small, and then slowly open the hole until the fan fits snugly into the hole. Cut the hobby foam sheet bigger than the opening but smaller than the end of the box, and then cut a circle in the middle that is about 1/4in smaler than the end of the fan. The foam should expand and form a seal around the end of the fan, and fill any gaps between the fan and the cardboard. Tape the foam to the inside of the box after testing to make sure the fan is lined up and fits. Cut a hole in the other side of the box to fit the fan snugly. I didn't use the foam on this side since I used tape to seal the filter into place. Before sealing the box closed: Attache the hose onto the end of the fan that is pushed through the end of the box and wire up an extension cable that will be able to extend the length of the hose back to the 'bot or wherever your source of 12V is. Then tape the box up air-tight. Keep in mind that the box will be pressurized in order to force the air through the filters and that any gaps or leaks will allow the air with the fumes you want to be filtered to go around the filter. That's bad, M'kay? This is the point I'm still experimenting. I don't suggest hooking this fan up to the EC, since it draws 3A and is probably very very noisy (electrically). I connected it directly to 12V from the PSU, but it's a flimsy conection and needs work. (Hint: On the PSU connectors 12V is usually yellow, and GND is usually black.) It's louder that I'd like. It's not vacuum-cleaner-loud, or heavy-equipment-loud, but it is about 3x louder than my 'bot. Granted, I can print when the house is asleep, so my bot is pretty quiet, but I can't run this when the house is asleep. I suspect that a second box around the main box with paper crunched up or packing material of some sort to absorb the sound will work nicely, but I haven't tested that yet.