Introduction: Solder Fume Extractor With Activated Carbon Filter
For years I've endured soldering without any ventilation. This is not healthy, but I got used to it and didn't care enough to change this. Well, until I got the chance to work in a lab of my university a few weeks ago...
Once you've experienced the huge benefit of a solder fume extractor you never, ever want to solder without one again.
I didn't wanted to invest much money or time, though. This design is simple yet pretty, can be build within an hour and is student-budget friendly. But most importantly: The air is not just pushed around, but cleaned through an activated-carbon filter. It has a "suction range" of about 20cm and can handle even gross amounts of fumes from additional flux.
Step 1: Overview
The assembly consists of for layers, each with its own function:
- The first metal mesh prevents parts from being sucked into the fan and potentioally damaging it. Since it is made of aluminum it withstands the accidental touch with a soldering iron or splashes of solder.
- The fan is the main component. It does not only create the airflow but also allows for easy attachment of the other parts.
- The activated carbon filter absorbs the unhealty fumes. It can be replaced by removing only one screw, reducing the maintenance of this device to the bare minimum.
- The second and last metal mesh holds the filter in place and protects it from mechanical damage.
The module attached to the side is optional and allows for convenient powering through a USB power supply or a USB battery pack.
Step 2: Materials & Tools
All parts have been sourced from aliexpress.com. Although it is a platform for Chinese sellers the quality is usually decent and the price is un-beatable. Offers and prices often change, so I've included links to search pages only. Occasionally products are not as advertised, but on every I got my money back every time.
|120mm 12V fan (can also be salvaged)
|metal mesh dust filter for 120mm fans
|M5 screw, 16mm long, countersunk
|1,67€ (pack of 21)
|activated carbon filter, 13*13cm
|4,61€ (pack of 10)
|MT3608 Step-Up Module (optional)
|Micro USB breakout board (optional)
*Cheapest price at the time of writing this article.
- soldering equipment
- 5.5mm drill (6mm should work as well)
- screw driver
- cutter knife
Tools required for the optional USB port:
- round file
- hotglue gun
Step 3: Thread the Holes of the Fan
Although the fan is not made for standard screws, the size M5 happens to fit quite well. It is a thight fit, so I recommend threading the holes first. You don't need any additional tools, you can use one of the screws you'll be using later. The friction generates heat which makes the process easier after a few turns. The fan may slightly crack under the pressure, this is normal for cheap chinise versions.
Step 4: Enlarge the Holes of the Dust Filter
Unfortunatly the dust filters are made for smaller screws, just like the fans. A 5.5mm drill is just perfect for M5 screws. The holdes do not even need to be pretty, they will be fully covered by the heads of the screws.
Step 5: Add the Step-Up Module (optional)
A micro USB port adds a lot of convenience in my opinion. It makes the device suitable for the most common power supplies and allows for easy portable use with an USB battery pack.
You can also attach a 12V power supply instead and skip this step.
To run a 12V fan from a 5V USB supply the voltage needs to be 'boosted'. This is such a common task that there are many different ICs and modules available. I picked the MT3608 because it can handle the power easily, fits well into the overall build and is incredible cheap.
Unfortunatly it is slightly to large. Use a round file to make a small indent to fit the turn-thingy of the trimmer.
Proceed to shorten the wires of the fan. Leave them slightly longer than required to allow for corrections later on. After tinning the wires, solder them to the output of the step up module.
Next solder the micro USB breakout board to the input. If you don't have such aboard at hand and are a little bit insane (like me) you can also solder a micro usb port upside-down to one of the ground (= minus) terminals. For high mechanical strength you have to heat the board and the connector thoroughly and apply some additional flux. Once the connector starts 'flowing' you can remove the heat. Carefully proceed to solder wires to the outermost pins, connect the red wire to + and the black to - .
Attach a power supply to the input and a multimeter set V to the output. Turn the potentiometer until the output voltage is about 12V.
I used a lab power supply to test this assembly and noticed that the fan is drawing way less power than specified. To increase the airflow tuned the voltage until it was running at its rated power of ≈2W, which was at about 15V. Be aware that this reduced the lifetime of the fan. Considering the price this was an acceptable tradeoff for me.
If everything woks as intended you can add the module with plenty of hot glue to the fan.
Step 6: Mount the Filter
The standard size for activated carbon filters seems to be 13x13cm. Take a cutter with a sharp blade and trim it to 12x12cm. Do not cut it any smaller, the mounting mechanism depends on the exact size.
Originally the filter was placed on the inlet side of the fan. Unfortunatly the filter touched the blades and blocked the fan. As a quick solution I tried to put the filter on the exhaust side to benefit from the plastic support. Surprisingly this didn't effect the airflow in any noticeable way.
So mount one of the two metal mesh filters to the exaust side. If you have installed the step-up module decide for an orientation of the mesh. Use three screws only and screw them in for about 2mm. Now you can slide in the activated carbon filter. Push in the corners to accommodate the screws. This creates the force which holds the filter into place. Add the last screw. Tighten all screws without squeezing the filter.
Finish the project by adding the front metal mesh, pay attention to match its orientation with the one on the backside. You can also add small rubber feet to reduce the vibration and noise.
Enjoy fume-free soldering!
Update 2019 Jan:
I've replaced the filter a few times before, but this time I've remembered to take a picture of the used filter. Even without the direct comparison you can clearly see all the stuff that would otherwise have ended up in your lungs. Stay healthy and have a great 2019! Cheers.