[DIY] Solder / Glue Fumes Extractor & Filter

Felt quite nauseous recently, after soldering for 4 hours straight in a small non-vented room. And a couple of 3D prints requiring superglue had me in tears. Who's dumb enough to get exposed like that ? 😅

So, looked up desk fumes filters but most were too small to effectively draw air from a large working area, had thin or throw-away carbon filters, were corded, or required messing with a hose system with a large footprint.

Instead I wanted a large inlet, a lot of replaceable filtering carbon to capture most pollutants in 1 pass, and battery power to easily move from a station to another.

 

Enter El Snorter:

  • 200mm large collecting inlet
  • ~1lb of acid-free activated carbon
  • configurable assembly to collect fumes from ~6" (15cm) away to ~10" (25cm)

It can simply be powered by an external power supply, making it a simple build, or by the optional battery power base:

 Optional Power Base:

  • 18v power tool battery
  • variable fan speed via DC-DC converter
  • doubles up as a variable bench power supply
  • switches and banana posts for power on, fan on/off, battery out, DC out

 

It took forever to develop a solution that can draw in fumes from up to ~10" (25cm) away. The best result was with a large fan in the front, and a blower in the back to overcome the back pressure from the carbon filter. In a nutshell: it is orders of magnitude easier to blow than to suck... 😅

In the end it worked well, and also does double duty as a portable variable DC bench power supply. Love it.

Since 3lbs of carbon in my 3D printer lasts ~6 months before PLA & ABS smells reappear, the filter should last a while before needing a carbon reactivation cycle.

Fusion 360 CAD, Step and 3MF printing files are all on Github

Happy fumes-be-gone to all !

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Table of content

  • Configurations
  • 3D Prints
  • Build
  • Parts
  • Carbon Reactivation
  • Failings & Learnings
  • Fumes Extractor Examples

 

 

Configurations

These configs are the result of many trials while searching for the most powerful extraction setup. They each have pros & cons: complexity, cost, effectiveness, footprint.

Personally, I settled on the Short Hood setup below. But, since other people may have different needs, I thought I'd publish all the variations tried. More on their respective results in the Failings & Learnings section at the end.

Just pick a config or mix things up as needed. However, never use the front fan without the blower as the airflow will stall and recirculate around the fan blades due to back pressure. Ask me how I know... 😅

From least effective to most:

A good middle-of-the-road config, that doesn't require using 2 fans, could consist in pairing the Blower+Baffle config with the Long Hood.

 

 

3D Prints

Settings:

  • max plate length: 242mm (back baffle), max height: 210mm (filter box )
  • PLA, 0.4mm nozzle, 0.2 layer height, 0.45 width
  • 2 walls, 2 to 3 top & bottom layers
  • infill: 10% grid default,  25% adaptive cubic modifiers under the large top surfaces
  • no supports
  • El Snorter / Fan / On-Off letters were printed in a different color after splitting the parts in the slicer. They are only 0.4mm thick, so the purge tower is just 2 layers high. If not desired, don't split the parts and just print monocolor

Filter plates (can be combined into a single plate):

Grille & Hood (pick one):

Baffle:

(optional)  Power Base:

 


Build

Start by installing 4mm long M4 inserts into the filter box: 4 for the front fan, 3 for the blower, 4 for the baffle box in the back:

Now the blower can be installed (3x 45mm long M4 bolts in my case), followed by the back baffle (4x M4-10mm), and the front fan + grille-or-hood (4x M4-40mm):

Cut a piece of window screen 200mm (7.8") large by ~400mm (15.6") long. Lay down the screen along one side of the cartridge, ensuring that the edge along the bottom is properly tucked between the central body and the bottom lip (right side of pic). Preglue the nail holes with superglue, and pin the edge of the screen with one of the 'nail bars':

Then pull the screen hard around the cartridge and pin / glue the other edge:

At this point the extractor / filter is fully functional. Just power it with a 12v source and enjoy the fumes being snorted away into the carbon's clutches 😤

 

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Optional: the Power Base provides portable battery power, and a variable DC bench power supply.

Holes were drilled into the battery box, matching the Makita 18v battery adapter's holes (or any power tool brand: Dewalt, Ryobi...). M4-15mm bolts hold the adapter:

Electrical box: four 4mm long M4 inserts were installed first.

Before mounting the switches / posts / etc, wires were attached to them, as working in the box is difficult and as soldering the jack posts can melt the PLA.

The voltmeter was installed first and secured with 2x M3-6mm self-tapping / wood screws.

The 10K linear potentiometer on the DC converter was desoldered and the 2 PCB tracks connected to it got wired up to a panel-mount 10K potentiometer. Making sure to use the 2 pins out of 3 that, when turning clockwise, make the converter's output voltage increase.

The DC converter was secured to the electrical box's lid with 4x M3-6mm self-tapping / wood screws.

Once all the parts were in, the wiring was completed per this diagram:

The battery and the electrical box can now be either glued or bolted together (2x M4-15mm).


Finally, the electrical box's lid was closed, with 4x M4 25-30mm bolts.

The Power Base is now complete and can be either glued under the filter box, or bolted on via 3x M4 20-30mm bolts, or just be used as a separate power supply device.

 

Done. Now go forth and hack away, smoke & tears free !


 

Parts

The 140mm blower (12V 1.5A 3000rpm $29) is more powerful than needed for this application. 120mm blowers are much more readily available, cheaper and suitable. But that's what I had. It works in 2-wire-only mode down to ~4V, providing great flexibility for dialing in sucking-power vs noise.

The acid free carbon used is made of coarse grains of carbon that are about 3 to 6mm (1/4") long. Finer carbon is available, and would perform even better as a 1 pass filter, but would likely present too much air resistance for this device. Here is a pic with a ruler for scale:

(optional) Although I ended up using the 'high pressure' 200mm fan model (12V 0.42A 900rpm 1.92mm-H2O 30mm thick $20), it stalled as badly as the standard 200mm model (12V 0.2A 800rpm 0.99mm-H2O $14) in the absence of the blower. Both work in 2-wire-only mode down to ~4V. Any other model would likely work as well, as long as the hole spacing is 154mm (not 170mm like some):

(optional) Used this $5 4-40V to 1.25-37v 2A DC-DC converter. But there is a myriad of similar LM2596 based converters that would do also, although with slightly different hole patterns.

(optional) This $2 0.36" mini voltmeter (23x15mm 0.9x0.59" opening) can be powered by up to 30V, so the power tool Li-Ion batteries' 20Vmax voltage is a no brainer:

(optional) Although I used a Makita battery adapter, pretty much any other power tool brand should work.

(optional) The 4mm banana jack sockets used are low profile and mount through an 8mm diameter opening. Note: those are installed with only the front plastic ring, as the 2nd one is only used as a spacer for thin panels.

(optional) The 2mm banana jack sockets use a 6mm diameter opening:

(optional) SPST switch (~20x13mm opening) for the fan:

(optional) DPST switch for power-on:

(optional) The 10K panel-mount potentiometer that replaced the DC-DC converter's 10K is a 40-some-year old Spectrol part from my drawers that looks like this expensive Vishay part below. But any pot that fits a 10mm diameter opening will do.


 

Carbon Reactivation

After a few months, once filtration loses effectiveness, one can try to rejuvenate the activated carbon. I am no expert here and there's confusing information out there about whether it is actually possible with basic processes.

My understanding so far: it is possible to remove the impurities captured by the carbon via thermal desorption when filtering mostly organic compounds (aquarium, kitchen smells, some 3D printing fumes, noxious farts...). In this case 200°C (400°F) in an oven is usually sufficient to burn away most of the organic material. Just don't use an oven in which food is cooked, and crack the door open to let the smoke out.

However, reactivation after filtering heavy stuff (like soldering fumes containing metals I assume ?) requires chemical regeneration, or 600-900°C temps, or steam reformation. Not an option for me, so I'll simply try an electric oven in the garage, cranked up to its 450-500°C max temp for 30'. Will see if sufficient for this application...

 


 Failings & Learnings

The most interesting part in any project, in my opinion, is the stumbles and learnings along the way. Much more interesting than just publishing a how-to-copy recipe when done. I'd rather be taught to fish than given a fish !

And oh boy, was there much fishing on this journey, am dreaming of chicken now 😂

First, regular fans don't work due to the back pressure presented by the 38mm (1.5") thick carbon cartridge, despite the coarse carbon grains used.

Even after switching from a see-through fabric bag holding the carbon to a window screen, which dropped air resistance a lot, the fan was still stalling as the air was being ejected back out front around the periphery:

Closing the 2 outermost vent rings fixed that and the device started drawing in fumes, yay !

Unfortunately, the sweetspot was very small, comparable to many smaller extractors out there.

Medium sized soldering projects constantly required repositioning things for the soldering iron to be no more than 4 to 6" from the grille:

So next was adding a hood. That helped but required squeezing soldering jobs under the hood.

Adding a second 200mm fan at the back helped some more:
 

But when a reasonably-sized hood got designed, signs of air recirculation between the back and the front showed up. A large baffle fixed that, but performance was still underwhelming past 6" (15cm):

So the 200mm fan in the back got replaced with a powerful 140mm blower.

Unfortunately, the expelled airflow was now so concentrated and energetic that it created an air lifting effect all around the desk, completely disrupting the sucking action in the front:

Once again, a baffle fixed that:

But, obviously, it is unusably large. So a folded baffle concept was tried, but failed:

Finally I got the idea to disperse and slow down the powerful air jet coming out of the blower, thanks to an enclosure sporting an exit hole on the opposite side from the blower's exhaust:

And that finally did the trick. Fumes were now consistently extracted from ~10" (25cm) away:

It even works pretty well with no hood. Though, without the hood's guiding vanes, the front fan has a tendency to make the ingested air rotate and get kicked out sometimes.

All that was left at this point was to design a 3D printed version of the dilution box for the blower (called Back Baffle in the CAD model).

The resulting extractor is quite noisy when running past 10V. Refining the design of the dilution box to dampen the noise would likely help. But other projects have been waiting for this extractor to get started, so time to move on.

Never mind that I initially thought it'd just be a matter of slapping a 200mm fan on a box... Had no idea that it'd take a couple of weeks to truly understand that, unquestionably, it is much easier to blow than to suck ! 😅

 

 

Fumes Extractor Examples

DIY Kirby by Chris Borge:

DIY Open Green Energy:

DIY by Tilan2000:

DIY carbon filter mod for Ikea Uaaptvind:

DIY by darbinorvar

DIY by badarsworkshop:

DIY Adafruit:


Commercial:






 

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