Do you need a small, effective workshop dust extractor with parts you probably already have lying around?
This one works great at sucking up and separating fine particles from cutting & sanding materials like wood and foam . It can separate chalk dust from the air. A device like this one will save both to save your lungs and vacuum cleaner bags.
After reading a few other dust extractor related Instructables posts, i got the basic idea of how to make a cyclonic dust extractor
But instead of messing around fabricating all the parts out of flat sheet stock i tried making one out of recycled PET soda bottles that had the same basic cone shape already. They also had another advantage, which was the built-in thread that could act as an easily removable attachment point for the dust catchment container.
This, coupled with some PVC fittings and some flexible hose, resulted in a project that was simple, cheap, compact and highly modifiable. Suction is provided by an old vacuum cleaner.
Obligatory disclaimer: I don't take responsibility if you hurt yourself or destroy anything making this. This design probably won't compete with any commercial grade dust extractor and wont provide the equivalent performance. It is not a substitute for a good mask or respirator either. Always observe safe practices when in a workshop environment.
Step 1: Some info...
The main working part of cyclonic dust separators is the cone shaped chamber that creates a vortex as air is sucked into it. The air increases in velocity as it approaches the bottom of the cone. As Velocity increases, centrifugal force increases and separates the heavier dust from the air. The dust falls to the bottom of the chamber as it runs down the sides of the cone into a collection container.
Check out the image of a cyclonic separator for a better idea. (courtesy of http://www.thefullwiki.org/Cyclonic_separation)
There are already good designs on Instructables (http://www.instructables.com/id/Dust-Sniper-quiet-extractor-system/ ) showing how to build a dust separator to use in a workshop, and i was about to follow their excellent instructions.
I noticed a PET soda bottle that had the right proportions of the cone needed to generate a vortex. Likewise i could use another PET bottle for the dust collection chamber. So, I figured i would save some time not cutting out 2D patterns out of plastic AND recycle at the same time!
There was also the added benefit of the thread at the top of the bottle that could work as a sturdy attachment point to easily unscrew and empty the collection container.