Introduction: PET Soda Bottle Cyclonic Dust Separator
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 (https://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.
Step 2: You Will Need:
The following is only a guide:
>1 largePET soda bottle with a cone shaped top (i used Australian brand Kirk's Originals Soft drink bottles)
>another PET soda bottle of any shape
>20mm and 25mm PVC pipe
>any vacuum cleaner
>Assorted 20mm PVC pipe fittings
>6mm MDF sheet
>a few meters of vacuum hosing or similar flexible plastic hose
>old punctured bike inner tubes
>one large postal cardboard tube
>one small Aluminium foil cardboard tube
>glue: Cyno Acrylate and PVA wood glue
>silicone window sealant
>Dremmel with sanding attachment
>I used a CNC router too. you can probably just use a jigsaw and hole saws though.
Step 3: Dissect Your PET
Once you have completed the quest to find a soda bottle with a cone shaped top (that is the hardest part) you will need to chop the bottom off it, leaving only the neck, thread and as much of the cylindrical body attached as possible.
I found that scissors work the best for me.
Try to get as neat a cut a possible that is nice and square to the sides of the bottle. This will make latter steps much easier.
To get a good cut. i recommend putting some tape around the bottle to act as a line to follow. Don't try to get it in one cut. Make a few cuts closer to the line each time.
Step 4: Make a "Lid"
Now you need to fashion a lid to cover that hole you just made in your bottle. This part will function to hold in place the air intake and outtake for the air stream. The lid will have two PVC pipes running through it to connect the hose , one leading to your vacuum and the other to your intended dust collecting nozzle.
The lid can be any shape, as long as it completely covers the lip of the bottle and you have enough space to seal up the joint with silicone. (In the photo you can see a grove routed into the lid to form a better seal with the bottle, this is optional).
You can use any material that is strong enough to mount PVC pipe. I have used 6mm MDF. There will need to be two holes for the PVC pipe that the hoses will connect to. Make sure you measure and get the spacing right to fit your chosen pipe.
One hole needs to be directly in the center of the lid relative to the bottle, the other just off to the side. These holes need to be square and snug for the pipe to sit properly. Their angle & position are important for the cyclone effect to take place inside the bottle.
Step 5: Mounting Air Intake & Outtake
Now it is time to secure two pieces of PVC pipe into the lid. These will function as the intake and outtake ports. This is where the vacuum hose will connect to the cyclone chamber, and another hose will connect to form the nozzle that will collect dust.
The position of the air intake and outtake is important, and i probably don't have it in the most efficient setup. However, by experimenting i found that having the outtake pipe (the pipe mounted in the center of the bottle that will lead to a vacuum) works well when it is sitting inside the chamber with the end of the pipe sitting just at the beginning of the cone . (see photo)
The other pipe will need an 90 degree elbow joint mounted at the top of the chamber, to direct airflow perpendicular to the air outtake, hence creating a spinning cyclone effect.
Air is sucked in at the top to the side, and exits out the bottom in the center of the chamber.
Once the pipes are in place glue them in with super glue. Place the soda bottle over the pipes and secure with silicone sealant. use sealant on gaps if any.
Step 6: Neck Connection
The dust separator requires a second chamber to catch the falling dust. For this we will be using a second PET bottle. To hold it underneath we will utilize the threads on each bottle's neck to hold them end to end.
Take the lids of the bottles and cut/dremmel holes in the tops (you will need to remove most of the material in the top of the lid) of them and place one in each end of a small cardboard tube (or other suitably sized tube). You may need glue to hold them in place. Make sure that the whole assembly forms an airtight seal between the bottles.
This component enables you to easily separate the 2 chambers to empty out the dust.
Step 7: Test Chambers
Connect the two chambers. Everything will need to be secure. You can now test your dust separator by holding a vacuum nozzle to the outtake nozzle (the center pipe) and taking a pinch of dust and dropping it in the intake nozzle. if everything is working fine then you will see the particles in the chamber flying around in a circle around the cone, hopefully ending up inside the lower chamber.
Be careful not to block the intake completely, you don't want to expose the assembly to a strong vacuum and implode (crush) your plastic bottles before reinforcing them.
If it works, that's great! If it doesn't implode. Even better.
In the photo i am using a smaller PET bottle as the dust collection chamber. You can go bigger if you want. You don't even have to use a bottle. You could just plug the upper chamber into a sealed garbage bin or something. As long as its all airtight and the dust is allowed to fall down into the container.
Also there is vacuum created inside the lower chamber too, if you use a thin walled container without bracing it my collapse .
eg i connected a 2Litre Pepsi bottle to it and it collapsed even when the intake wasn't blocked.
Step 8: Making a Stand
The PET bottle dust separator doesn't stand upright on its own very well. So i made a stand for it. Not only does this stand hold it conveniently upright but it also provides some vital bracing to stop the bottles imploding.
The stand is simply a Cardboard postal pack tube. The soda bottle fits very snugly inside, so that the surrounding cardboard acts as bracing and won't allow the bottle to buckle under vacuum .
The Cardboard is glued to a piece of scrap mdf as a base. There is also a 1.25L coke bottle filled with water inside acting as ballast.
To empty the dust collection chamber, you just need to lift the chambers out of the tube.
Step 9: Practice Safe Hose Coupling
To make some hoses for the Dust separator i used 2 lengths of plastic drainage pipe (like from a washing machine's water outlet).
I would recommend using proper vacuum hoses though, as the light, thin-walled water piping resonated loudly at lengths over one meter. however the lengths i used were about 1 meter, and didn't really make to much noise.
To connect the hoses to the dust separator i attached PVC fittings to the ends of the hoses. this made connecting/disconnecting easy. To save on duct tape i devised a way to attach the PVC to the hose using pieces of an old bike inner tube. this is easier to remove and is somewhat more flexible than permanently gluing/taping them.
-Cut a 3 inch section of an inner tube
-stretch it over the PVC fitting (in this case an elbow joint)
-place a 3 inch piece if PVC pipe into the fitting into the end you just placed the rubber over.
-roll the innertube up the PVC pipe and over the lip of the fitting (like a condom :P )
-place the hose over the PVC pipe, snug against the fitting and roll the inner tube down over the hose*.
*you will feel a little weird doing this step...
if done right it should form an airtight connection. See sequence of images for better understanding.
Step 10: Connect It Up
Now you can attach your hoses to your dust separator. Make sure that the vacuum plugs into the pipe that is in the center of the upper chamber, and the other hose is on the other pipe. If you connect it the other way round it wont work.
I cant tell you how to connect the hose to your particular vacuum, its probably different to mine. Just do the best you can. I used a rubber connector that came with the hose that just happened to fit exactly into the vacuum's intake port.
Use cable ties to secure the hose out of the way, but with enough room to maneuver.
If there is any high pitched whining coming from the hoses try shortening them. Otherwise try getting different hoses that are heavier/thicker walled.
Step 11: Dust Hood
For use with my CNC router i needed a dust hood to direct the dust into the vacuum nozzle. I designed a part that would clamp onto a Bosch Colt, and a port for some PVC pipe to connect onto.
I Routed it out of 6mm MDF then added a screw & nut to tighten it on. I then made a skirt by gluing a cylinder section cut from PET bottle, then made some straight cuts to form some 'bristles' into the plastic. I then cut off the bristles level with the spindle (if they are too long they might get pushed into the mill bit).
It works great for 2D profiling. The bristles flex over the part as the router cuts away.
Step 12: Thats It
There, all finished!
I hope you found this instructable useful. the idea isn't original but i think the way I've done it is. I want to encourage improvisation in any design, and i encourage you to make this one better. It has some problems, its noisy and ugly. But it cost me basically nothing to make and it works better than i ever thought it would.
Note: try not to suck up objects larger than your fittings, they will get stuck. It is only good for dust and other small particles.
Don't forget to empty out the dust collection chamber every so often.