I really like instructables, it is for me a really nice source of inspiration. This is my turn, hope you'll like it.
The most common DIY smoke absorber use a simple DC fan and a piece of cooking fan filter. This works not so good. I used one a couple of years... It is noisy and doesn't sucks so well when the soldering is not right under the fan. Some fumes just pass throught the minimalist filter as well.
Another way to not breathe the fumes without a super fancy filter is to extract it outside your shop. The main problem of a chimney is that it will use pretty big ducts, which might be difficult to route outside, especially in a flat you rent...One of my friend simply solder on his stove, with the fan on. For my side I prefer to keep soldering at the same place than the rest of my lab.
Step 1: Inspiration.
This weller system gave me inspiration. A nozzle is attached to the iron and sucks the fumes right where they are produced. A pump aspirated the fumes trough a filter.
Of course a similar system could be use without a super fancy filter if the exhaust of the pump is routed outside your shop. In that way, you obtain a chimney system how doesn't need a huge duct, as the volume of air to pass is really small. A tiny hose is then enough and will be easy to route outside your flat trough a window or a small hole.
Step 2: Nozzle for Your Soldering Iron
Whatever rigid tubing of the right diameter will do. I looked for an aluminum tube, but ended with a part of brake line as the hardware store I went sold more auto parts than aluminum tubing... I built two aluminum tab to attach the nozzle to my iron. Note that for testing it was just attached with gauge 14 copper wires for a couple weeks. It didn't hold so well, but if you want to try it will be good enough.
Good thing is that the stand I had can fit the soldering iron with its nozzle without any modification. It will be another problem with a spring style iron stand. I'm sure you'll find a way.
Step 3: The Pump
How to build a similar system with your own soldering iron and salvaged parts?
In the North American city I'm living, it is common to see a fridge on the sidewalk, already salvaged by the copper guy but with the compressor in a perfect shape. So I found one and kept the compressor, known as pretty good vacuum pumps.
Once you found one, rewire it if needed and add (if you want) a foot switch. You should appreciate it!
Make sure to keep the rubber pads as well. No really need for any screws. My compressor is just laying on the floor, under my bench and never moved.
Cut the copper piping as you like to fit a hose on the outlet of the compressor. In my case I soldered a piece of a 1/2 copper pipe to fit an old garden hose. You could use smaller PVC hose as well.
I did the intake hosing adapter with automotive (fuel line) rubber hosing.
Step 4: Oiling Consideration
As you certainly know, there is oil inside the compressor. When used in a cooling system,the oil stay in the circuit. As my outlet hose is not transparent, I don't know how much oil is going out, but I'm pretty sure some is going out. Something like a receptacle to catch the oil at the outlet of the compressor might be useful.
At least it is still working without it after a couple month now....
Step 5: Filtering
I didn't want small particles to somehow break something on the compressor. Beside of that it might also pollute the oil inside. I putted then 2 inline gas filter on my system. One located at the same distance than the power supply of the soldering iron and one bigger at the intake of the compressor.
Good news is that a cheap ($3-5 in any auto part shop) gas filter will last a couple weeks to a couple of month for a DIY use. As you can see, the fumes quickly makes a white deposit, that will at a point completely clog the filter (first picture). The second filter (second picture) stayed clean during the same time.
I'm now asking myself if a bubbling chamber in water, such as a shisha would help to catch particles... I didn't try it yet, and my system is working well for a couple months now. If you try it let me know.
Step 6: Hosing
I used transparent PVC hose from the nozzle to the pump. It would be better (softer) to use silicone hosing.
At least, PVC becomes softer pretty quickly as it sucks warm air. The outlet is an old garden hose, easily routed outside my flat trough a vent hole in the basement.
Step 7: Complete Setup
You can now complete the setup. Secure the PVC or silicone hose to the electrical cable. The compressor is simply left on the floor under the bench. Make sure to keep the rubber pads under the compressor. I didn't even had to screw it.
Step 8: Plus and Minus
This system was pretty easy to build. It seems pretty efficient, and a really really nice point (at least for me) is that this system is really quiet. Beside of the soldering iron, a similar system could be used with an acrylic laser cutter...
For the minus:
If you feel more power, just use a A/C unit compressor. This will be much more powerful (also much nosier but this is your call).
I would like to add a bubbling chamber and an oil catcher, to be sure my system is going to last.
Sometimes, the nozzle is on my way when soldering. I become used to but it can be annoying specially at the beginning.
It is hard to whip correctly the top of the tip. Steel wool might help.
Hope you will enjoy your new extraction system as much as I do!