With my laser engraver and soldering, lots of harmful fumes, so decided to make a small portable fume scrubber with the cheapest material avaliable.
Let's see the BOM:
- One iPhone S box (very stiff and easy to assemble) also free (any kind of sliding box works).
- 300 grs. of activated charcoal
- Non woven fabric porous bag, with suitable size (you can use a bigger and cut it.)
- A small cardboard box (Can be any box that fit at least 100 gr. of charcoal).
- 2 60 to 40 mm adapters (you can print).
- 2 x 40 mm. fan 12 VDC
- 1 x 2200 mA Lipo battery 1C discharge or more.
- Connectors and cables, use any kind of polarized connector for fans and battery, I've used JST type.
- Cable management sleeve or cable ties.
- Duct tape and small gauge wire to conform a flexible duct.
- 40 mm. to round adapter (you can print it too.).
- Screws and nuts (1.2 mm or some suitable)
- Duct tape and Kapton tape (regular or electrical tape work too).
Step 1: Make Perforations on Box
Perforate the box to fit the 60 mm. adapters, for that you can use knife and drill or as in my case a CNC router, take care of dimensions and place holes evenly on the surfaces, to distribute them evenly.
Fit the adapters properly with screws, you may use plastic washers (or metal if you wish).
Step 2: Securing the Fans
Secure the adapters and then the fan as shown. see how preview of the battery placement. This is an example I've used to kind of adapters but you can use the same, or build them from cardboard and glue.
Adapter files are:
- Box to tube
- Box to fan
Thanks to 3D model authors.
Step 3: Fill the Charcoal
Fill a non woven fabric bag with the charcoal in an amount that fit nicely in the box as shown. Provide full coverage, but don't pack so thigh that airflow is obstructed and don't get any suction. you can adjust later, but need to ensure full coverage of the complete air path to capture as much fumes as possible. Not a scientific approach but you will notice the capacity of the filter when sucking from laser engraving.
Step 4: Suction Tube
Over a 1 1/4 inch PVC tube as a form (32 mm) you need to roll duct tape in a spiral way, ensuring some contact every turn to let the duct overlaps about 5 mm. to conform a airtight tube. The sticky face of the duct tube has to be outwards and the winding need to be loose and you may use a paper sleeve first to let the conformed tube can be easily pulled out when finished.
Once you conform the duct tape layer, you need to wind the steel wire to allow structural integrity, also taking care of not apply to much pressure in order to be easy removed from PVC tube when ready. see picture.
Finally use Kapton or just clear tape to finish and get the wire on place when finished. at the beginning and end place a couple of turns to secure the ends and provide enough strength and prevent wire to unwind.
Step 5: Finishing
Close the box with the charcoal box inside. connect the fans in parallel (positives and negatives together), you may use any polarized connector but O choose JST power ones because I have a couple and solder them together. Then place some shrink insulation to the junction (you can use adhesive electrical tape). and ensure polarity of battery, charge battery and test suction. If suction is too faint, then you may remove charcoal as needed, taking care of having as much as coverage a possible in the whole volume of the box.
Then test the fume extraction and let the fan run for a while to see if trapping is OK. use plastic fumes to see stringent odor to guide on capacity of the filter. Mine worked OK with laser engraving and soldering fumes.
Note that this cant prevent 100% of fumes to be trapped, neither are suitable for toxic gases or moist ones.
This is very basic and some details are not here but I'm happy to provide if you're interested.