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In case you didn't know this yet, compressed air is pretty awesome.  With simple mechanical systems - pumps - energy can be stored and used for an infinite amount of applications.  What I like about compressed air is how simple and accessible it is.  Anyone with a bike pump can start moving air to greater pressures.  Soda-pop bottles can be turned into air tanks, and by looking a little online and on Instructables, you'll find people who've used compressed air to do everything from shooting water balloons to powering a bicycle.

In this Instructable, I will show how I made a miniature compressed air turbine.  

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8/16/13: Thank you for the feature!
8/16/13:  I'm just shy of 9000 views in barely 12 hours!  Thanks everyone!

Step 1: Video!

Step 2: "A Compressed What-!?": Theory of Operation

Let's start from the very beginning, shall we?

All matter is composed of atoms.  In solids, these atoms are packed very tightly together, which is why they are -erm, solid.  The atoms are forced together and don't flow around much.  In a gas however, the atoms are able to move around freely.  So freely in fact, that gases don't have a "form", and instead take the form of whatever container they are in.  Gases can be held at different pressures.  The pressure of a gas is a reflection of how many atoms are forced into a given space.  By using a pump, one can force more gas atoms into a space, increasing the pressure.  If you have a container filled with a gas that has had extra atoms pumped into it, and you open the container, the high pressure atoms will move to the area with the low pressure atoms until the overall pressure is equal.  The concept that a high pressure gas will move to an area of lower pressure is the concept that will drive our compressed air turbine.

The compressed gas will move through the turbine to the area outside the turbine.  As it moves through it, the air will push the fins, and cause the turbine to rotate.  The gases will move toward the center of the turbine, where they exit the exhaust hole.

I made a really fun .gif showing the air molecules being compressed, and then moving the turbine!  I hope it helps!

Step 3: Tools/Materials

Very few tools and materials were used to make this turbine.  Here they are!

Tools:
  1. Epilog laser cutter
  2. Inkscape1
  3. Dremel rotary tool
  4. Hand drill
Materials:
  1. 1/8" Acrylic sheet - I used a cool orange one I found in the shop.
  2. 6-32 threaded rod.  It's roughly 1/16" diameter.
  3. 6-32 washers and nuts.
  4. 1/8" diameter brass tube - this is from K&S metals and I got it at the local hardware store.  Awesome tubes to work with.
  5. 5 minute clear epoxy
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1.  Inkscape is an open-source vector graphics creator.  If you've heard of Adobe Illustrator, this is like a free version of that program.  I'm using it because it's free and available, but feel free to use your vector-graphics editor of choice.  Or you can get Inkscape for free here.

Step 4: Design - Turbine

I designed my compressed air turbine in Inkscape.  Everything was kind of made up as I went along since I'd never used the program, and had no purpose in mind for the final product.

Not familiar with Inkscape?  I highly recommend reading through this first.  IT helped me find my way around and will help you follow the instructions below better.

To draw the center turbine, I did the following in Inkscape:
  1. Make a new image.  Click "FIle>Document Properties".  Set default unit to "inches"; "width" and "height" to 1; and grid to 1/16" or .0625.
  2. Draw a circle.  Click the center of the grid, and hold down "Shift" and "Ctrl".  Drag the cursor to a corner, where it will snap to the grid to form your perfect, 1" diameter circle.
  3. Draw a hexagon.  I wanted my turbine to have six fins.  Use the same technique as that used for the circle in the previous step,  but stop when the corners of the hexagon contact the edge of the circle.  It may help to go into the Document Properties and turn off grid-snapping for this.
  4. Convert to "nodes".  Select the hexagon and press "Shift+Ctrl+C".  This will change the object to a path, which will let us manipulate it more easily.
  5. On the right hand side, there is a toolbar, with a button to allow "snap to cusp nodes".  I had this feature turned on for the majority of my node-manipulation work.
  6. Draw guidelines.  I draw a line segment from the top node of my hexagon down.  This segment was copied, pasted, and rotated 60-degrees multiple times, and placed on all the corners of the hexagon.
  7. Node-manipulation.  Select the hexagon, and a node.  Use the "break-path" function to break the path at that node.  Select a node at the broken point and drag it to the bottom of the line segment.  This is where it should "snap to cusp node".  Repeat this for each corner.  Select each corner, and "join selected nodes" to make one solid path.
Follow all that?  I'm exhausted writing it.  Take a deep breath and let's move on!

Step 5: Design - Housing

Now that the center, and only moving part is designed, we'll need a housing to make everything work!
The housing itself is composed of layers.  These layers bolt together to make the housing one piece.  I attached .pdf's of each layer!  The .svg's were unhappy when I tried to upload them..

Center-housing:
          - where the turbine will spin inside of.
  1. Make a new document.  Set default units to "inches"; "width" to 1.44; "height" to 1.44; grid to 1/16", or 0.0625.  This turbine is tiny!
  2. Copy-paste the turbine we drew in the last step into the center of the new document.
  3. Draw holes.  These will be used for assembly later.  I used the same technique (Shift+Ctrl+drag) as in the last step to draw perfect, 1/16" circles, and positioned them with the help of the grid around the turbine.  These ended up being too small and had to be drilled slightly for ease of use, so keep in mind that you may want to make them larger.
Intake-housing:
          - where the air will flow into the turbine.
  1. Begin with the Center-housing we drew above.
  2. Select the circle in the center of the turbine.  Convert to path.  Break path at selected nodes.  I selected the one on the right-hand side of the circle.
  3. Use the "Draw Bezier curves and straight lines" tool, along with the "snap to nodes" function to draw lines from the broken circle to the side of the housing.
  4. Remember to save this as a different file, so you don't overwrite and lose the Center-housing.
Drive-housing:
          - where the shaft will leave the housing, and be able to do work.
  1. Start with the Center-housing we drew above.
  2. Select and delete the turbine and circle, leaving just the center circle in place.
  3. Save as a different file.
Exhaust-housing:
          - where air will exit the turbine, and the shaft will be supported.
  1. Start with the Drive-housing from above. 
  2. Copy-paste the center hole, and move it down slightly.

Step 6: Assembly!

Designs have been made, and you've used a laser cutter to cut them out.  Setup will depend on what type of laser cutter you have available.  For my project each file was exported as a .pdf, and then imported and arranged into CorelDraw, because it's a program that plays nicely with the laser cutters.  The pieces were cut out of transparent orange acrylic.  The protective paper over the parts needs to be peeled off.

Approximately 1.5" segments of 6-32 threaded rod were cut using a Dremel rotary tool with a cutoff wheel.  These were put into the holes on the corners, and held in place with equivalent nuts.  The holes on the corners were made slightly wider with a hand drill for ease of assembly.

The shaft was made using a 2" section of the same 6-32 threaded rod, and two of the turbine pieces were threaded on to the center.  Two small washers were used to close the space in between the turbine pieces and the sides of the housing.  The center holes were both made slightly wider with a hand drill to allow for the threaded rod to move more smoothly.

A small section of 1/8" brass tube was cut using a Dremel rotary tool, and the air intake was widened to allow it to be epoxied into place inside the turbine after it was bolted together.

Step 7: Conclusion!

There you have it!  A miniature compressed air turbine!

I'm not sure if I will ever use this for a project, but I may some day!  More than anything, I've always found turbines fascinating, and love the sound they make when they get going.  The possibilities for this little turbine are quite wide.

This design makes a small turbine, roughly 1.5"x1.5"x0.625" in dimensions.  What I think is really awesome is that it can be made larger and theoretically more powerful by simply cutting and bolting in more layers for air input, more turbine pieces, and making more exhaust holes in the Exhaust-housing.

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You should leave me a comment!  I like those! They help keep me motivated to publish articles instead of letting the pictures I took rot on my hard drive! : )
<p>I bought an educational kit/toy made by &quot;Thames &amp; Kosmos&quot; that uses both air and water to drive a turbine. I would be interested to know which would be more effective: air alone or air and water combined. I'm planning on using the air and water turbine to create an eco friendly motorized bike. But an air turbine would be less bulky and probably easier to make. I would appreciate any thoughts or comments. e-mail: photocool@hotmail.ca</p>
How WEAK can you make it? !! Because if you can make it to run off a solar panel and provide 1 psi or so, it can fill a huge need in my project! Last year I started a low pressure pneumatic grid project. It usually pumps water with the airlift pump process. The beauty of low pressure air and the airlift pump is that you have a central air compressor and the pumps are just tubes joined together. NO MOVING PARTS IN THE PUMPS! I currently run 9 pallet gardens with constant watering on my grid. And the project works really well. One weakness is that there are no decent low pressure air pumps available to run off dc from a solar panel. You can get low pressure air to run aquaponics, hydroponics, kinetic sculptures, mini water wheels on ponds, wash root vegetables or clothes, dry fruit, cool stuff as you dry it, and more and more! Mine runs off 3 psi air from an aquarium fish tank bubble pump BUT it actually only uses about 18 inches or about 3/4 psi. I have used it so far to cycle water for &quot;pallet gardens&quot; and vertical pallet planters. Some people in the windowfarms community have used my designs for this in Windowfarms across the world. I think I use 7 Watts to run everything.
<p>If there are low pressure air pumps that run on ac, then you could use a circuit that converts your dc voltage to ac.</p>
That sounds pretty awesome! Mine is able to run by blowing into it when the adapter is taken off. IT's a very small pressure but has not been measured.<br><br>Thanks for the comment!
This is something I can use for a big project I'm working on. I need to drive a small exhaust fan with compressed air. Is this something you would be interested in building and selling ? I'm building my prototype now and would be interested in purchasing one from you if your interested.
<p>is there a file I can download to print on a 3D printer?</p>
nope! This one is only for a laser cutter. However, I've started modeling a 3D printed version a few times and never gotten around to finishing it and printing one, mostly because I don't have access to compressed air nowadays.
good idea
Try adding it to the back wheel of a bike and you will have a air compressor so that you can power a LED light on the front or back
sorry wrong thought it was supposed to say air compressor for pumping up your tires... I am not awake enough to think lol
<p>I would cover the sides with metal for added safety, it could explode at high pressure. I would also add some bearings, because the thing stops really quick, meaning that it has a lot of friction</p>
Those are some very valid improvements to be made! Bearings for sure would add a lot of value. Thanks for the comment!
<p>Hi,</p><p>I really liked your video. Just curios how did you calculate the turbine blade size. because i am trying to build one for higher psi (1000psi). if possible can you send me the link to your calculations, if you did any or have one.</p><p>Thanx</p>
<p>1000 PSI is alot, you need to be looking into blade design. I'm not sure if it can be safely done without better understanding. </p>
<p>I would also think it would need SERIOUS bearings to sustain the possible RPM.Ceramic or whatever turbos are using now(outta the loop on that stuff).Be careful,may invent a warp drive or open a worm hole!,lol.Good Luck!</p>
I didn't actually do any calculations for the size of the turbine blades. I would guess that smaller blades would also be beneficial with a higher pressure turbine, to increase their stability. Thanks!
<p>Hi brilliant I don't know if you have a way of counting the RPM but if you made the contact face of the rotor concaved you should find a significant increase in RPM . If you don't mind me copying your design, I have a prop RPM meter which I will put a small propeller on your turbine (I have a laser cutter to copy it ) and I will measure the RPM with your design and then a concaved face to see if it does make a difference. then I will let you know. </p><p>All the best</p><p>Peter</p>
I would love to see you replicate my design! If you decide to, I'd love to see some pictures, or. RPM measurments if you're inclined. Since writing this, I finally have access to a laser cutter again, so perhaps that's reason enough for a mk. 2.
Well Done Fozzy. <br>It's good to see people who actually make things, and get them working, rather than just talk about them. <br>I would imagine the speed is extremely high, maybe up to 30 or 40 thousand rpm. <br>Ceramic Bearings are good for up to 100,000rpm if you ever need them. But they are a bit expensive. <br>Keep up the good work.
Thank you!<br><br>Judging by the sound, I definitely think the RPM's are up there which makes me pretty happy, but I haven't measured.<br><br>Thanks for the comment!
<p>HI if you go to a RC plane shop there is a Gadget called the Field Master7 which can count the RPM with an in build Optical Tachometer all you would have to do is buy a small prop and you could measure the RPM all though with the prop it would be about 20% less than with out. But it cost me &pound;20 or $26, but on Ebay you could buy it for far less, seems extreme but bloody good fun</p><p>Regards</p><p>Peter</p>
Thanks Fozzy. <br>Do be careful of those high RPMs. If the wheel were to disintegrate, it would fly apart at many hundreds of m.p.h. <br>You wouldn't see it happen, it would all be over in a split second, no time to blink. <br>So, please wear safety specs. <br>Remember, you're using your last set of eyes now. <br>Have you tried lubricating the shafts?
I haven't tried lubricating the shaft. It's a loose fit, and not airtight, so I don't think it would help much, but I suppose it can't hurt..
Interesting, but I don't really get it. What applications does it have.
If you can think of any application where a small electric motor could be used, this could be used instead and run on air power! That said, it was made more for the sake of making one than for it to actually be put to work..
<p>This would be a very nice source of torque for engraving, and it's self cooling too. Unlike an electric motor, this weighs less and does not heat up. Stalling this motor would not hurt anything, again, unlike an electric motor. <br>Very good!</p>
<p>Hi, I am really into your air turbine, but I do have some questions. Like I understand the input of the turbine, but what about the output. Where does the air go?? Would not it just be building up pressure until it blew up? If you could email me that would be great. minnich317@gmail.com</p>
In Step 5, there's an image that points out the exhaust housing piece. There are two holes in the center of the piece. One holds the axle, the other let's out the exhaust.
Do I glue the three rotors together
I didn't, but if I could do it again I would have. I relied on the threads to hold things together, but at higher pressures mine actually spaced apart a little bit. I would recommend gluing them.
<p>Would you worry about un-even glue distribution unbalancing the rotor at high speed causing failure at the shaft bearings ?</p>
<p>I wouldn't worry about that. This turbine doesn't even have bearings! What I would do most likely is put super glue in between the rotors at the center, and then push them together firmly, so that the excess super glue comes out the sides. The excess would be wiped off, leaving a thin, even layer of super glue between the two layers. </p>
sorry, may i get more detail dimension about this design? i try design on scale to 50mmx50mm but when air move to blade, three blade don;t spin because friction with inside wall then i release one blade so the rest are 2 blade and it is spin, but it don;t work because too much losses air on exhaust hole... may i got your suggestion? and email so i can contact more detail on email with CAD program (inventor)... thx
<p>try sanding down the rotor sides a little, just a thought</p>
This really reminds me of a toy car I had a few years back, it ran off of air and had a piston that would expand and contract like a real motor but instead of gases moving it, it was compressed air. When the tires moved the piston to a certain point it would put some gas into the chamber and propel it forward. It was a really cool design. I sold it though for like 30 bucks and I regret that now because it went up a lot. It's vintage 1980's too. <br>Heres a link <br>http://www.ebay.com/itm/Vintage-1980-Tomy-Air-Jammer-Road-Rammer-Car-Clear-Body-/261269733313?pt=Vintage_Antique_Toys_US&amp;hash=item3cd4e3bfc1
I've had a few different toys that used small piston-based compressed air motors. If I had had more time when I worked as an Artist in Residence, I may have tried to 3D print one. Compressed air is so much fun. <br> <br>Thanks for the comment!
it works and sounds like a dentist drill , it is epic i must say
Thank you! I'm very happy with how it works and sounds : )
I have to ask...does it double as a bong?
Just because it has two holes does not mean it is also a bong. No. But I'm happy to answer the question.
It looks to me that the Exhaust Hole is covered by the Turbine. Is there a space there?
There is a space there. The rotor has a washer between it and each end of the housing.
Neat! <br>Went to my Blog: <br>http://faz-voce-mesmo.blogspot.pt/2013/08/uma-micro-turbina-uma-mao-artificial.html
Silly question.... <br>You mentioned using 1/8&quot; acrylic...without anything to compare it to in the images, it's hard to tell, but that looks like 1/4&quot;....
I promise you it is 1/8&quot;! : )
Nice project. When you need to use a lasercutter you can look for a FabLab. They will have a lasercutter and maybe a 3D-printer. And in a real FabLab you can use their stuff for free or you pay a small amount of money during their 'free hours'. I am a labmanager in a FabLab in the Netherlands, every thursday afternoon you can use this Lab for free!
I seem to live in a maker's wasteland.. The closest FabLab or TechShop is at least an hour away from me, but I have been looking for places that can get me to more resources..
are laser cutters easily accessible to most people. Seems like many have access and ive never seen one in person. <br> <br>INteresting item im just really curious why I've not see one yet
My first introduction to them was from the Milwaukee Makerspace and we now have 3 in our inventory. <br> <br>I'd highly recommend looking for a makerspace in your area which may have one available to members. Additionally, there are many companies which will laser cut your designs for a price. <br> <br>There are some affordable &quot;hobbyist&quot; models out there, but their price tends to be around $5-$6,000 starting.
Thanks I've looked them up and I live in a major city which is a good thing but they're on the opposite site of the city. I wonder if one could be made piece by piece. Control through an arduino or similar device, The laser Id guess would be the most costly. Hmmm Ill have to look this up.

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Bio: I am currently a mechanical engineering student at the University of Toledo, and the founder of the University of Toledo Maker Society. I have a ... More »
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