I made a number of these "tornado machines" in the past and everyone usually enjoys them but because I make things in such a careless way I often don't take photos and everything is one of a kind. However, Instructables is helping me to change all that. Now I plan and research and make models and document everything. So, now I have enough information to give to you about how you can make a TORNADO MACHINE (or whirlpool machine if you wanna be technical about it.)
Add a Teacher Note to share how you incorporated it into your lesson.
Step 1: Gather Materials!
1. Gather the necessary items!
-Glass salsa jar, or similar with the thin metal lid.)
-Some HDPE (High Density Poly-ethylene) Look for empty plastic containers around the house they should say HDPE on the bottom.
-Small electric motor with a long shaft.
-Assortment of rubber bands (different thicknesses and widths)
-Sharpie marker. (or other permanent marker)
-toothpick, or wooden skewer stick or similar.
-Electrical tape. (only a small piece)
-Quick dry epoxy. (JB WELD would work. Super glue brand 2 park clear epoxy is what I used)
-Hot glue gun.
-Petroleum Jelly or Dielectric grease. (Or really any thick greasy substance that will stay in place)
-Silicone sealant (or other waterproof sealer, OPTIONAL, use at your discretion.)
-Plastic medicine syringe (OPTIONAL)
-various tools for cutting and filing.
Once you have gathered the materials you may begin. Remember that none of this is set in stone, you are welcome to try different containers and materials. This plan has been set to be easily accessible and quick to build.
1. Grab the HDPE container and cut out a circle about 2” in diameter, exact size is not important. If using a container similar to the one in the picture, put the hole in the middle of the container, we will use it again later. Put small hole in approximate middle of the HDPE circle. This hole needs to be smaller than the motor shaft so the shaft will fit tightly.
2. Put the HDPE circle on the motor shaft and apply power to the motor. Now, take a sharpie marker and lightly touch the spinning HDPE with the marker about ¾” away from the shaft middle. Now turn off the motor. This should have produced a black circle on the HDPE with the motor shaft hole being the precise middle.
3. Cut out the circle in the HDPE. And cut "fins" approximately as shown. Precision is not necessary but do not cut too close to the center hole. ¼” fins work just fine. Once fins are cut, go around the circle and bend each fin in the same direction, as the picture shows.
PRO TIP: If making your own impeller sounds like too much work then try to find a small hand fan. The kind you can get at the dollar store (see image). It usually takes 2 AA batteries, has a motor you may be able to use and a ready made impeller that fits the motor shaft securely. This way you wont have to bother with the glue on the impeller, but you will have to cut the fins down to fit your container and the motors are usually weak and under powered, which is why I am not using it. So I guess that makes this less of a pro tip and more of a noob step. Ah, whatever!
Another PRO TIP: The shape the tornado will take is directly effected by the impeller. The width of the overall tornado is directly proportional to the diameter of your impeller. IE; bigger circle of HDPE equals wider tornado. BUT a wider tornado will take more energy to get it going and won't reach the same length a similar powered motor using a smaller diameter impeller would. To summarize. Smaller diameter impeller = taller and faster moving tornado. Larger diameter impeller = wider, shorter and slower tornado.
4. Next, grab the lid to the glass jar. Put a small hole in the lid using a small drill. It needs to be larger than the shaft of the motor but not much larger. We want the shaft to spin freely but don't want to leave such a large hole that we will have to leak proof later.
5. Test that the shaft spins freely in the jar lid by applying power while the shaft is in the hole. Clean the hole and make sure there aren't any metal burrs that will damage the shaft of the motor or the rubber “o-ring” that will be constructed later.
6. To make an “O-ring” I use a rubber band and coil it around the motor shaft. I then put a small piece of electrical tape around the coiled rubber, so it doesn't uncoil itself. Each layer of the rubber band should be flush with all the others, so the ring can sit flat on the lid. See the images for a clear understanding of this step. Don't be discouraged, this is by far the most difficult part of the build. Take your time to get it right. Make a few coils if you have extra parts and try each one to see which works best.
7. Test fit the “o-ring” by applying petroleum jelly to the tip of the motor shaft and inserting it into the center of the rubber band coil. This will take a little bit of work. The rubber can be quite difficult to work through without enough lubrication. Keep applying the jelly and inserting the shaft. It should slide in with a little resistance but not so much that the shaft will get stuck. If the coiled rubber band is securely taped then you can test the fit by running the motor while it is lubricated and inserted into the center of the rubber band “o-ring”. See pictures for helpful details. If the shaft can still spin even while you hold the rubber coil in place then that is a good fit.
PRO TIP: Try putting some petroleum jelly into a oral syringe (See image) and squirting the petroleum jelly into the center of the rubber band coil. This will also be helpful later to add more lubricant as necessary.
8. Slip the rubber coil onto your motor. Then insert the shaft through the hole in the metal lid (see picture) This will line up the rubber coil center with the hole in the lid. Once they are aligned start adding some hot melt glue to the outside of the coil. Go all around the outside of the coil with the hot glue. DO NOT PUT HOT GLUE ON THE TOP OF THE RUBBER COIL. Also do not glue the motor in place. Once the hot melt glue dries, remove the motor from the rubber coil. You should be left with a rubber coil/metal lid assembly.
PRO TIP: Remember, each time the shaft needs to be inserted into the rubber coil you will need to apply more petroleum jelly.
The rubber coil will be our main way of keeping the water in the container. But I like to add layers of protection. The more the better. This is why the motor needs a long shaft.
9. Now we need to make a water-proof rubber membrane. Grab the balloon and cut a 1.5” diameter circle out of it. Don't make the balloon circle too big or it will get in the way of putting the lid back on the jar. Obviously the shape and cut of the balloon doesn't need to be perfect, just look at the picture.
10. This step must be done quickly so read the entire step before proceeding.
Clean the inside of the metal lid to make sure no petroleum jelly or dirt is stuck to it, this will assure that our hot glue sticks to the lid. Put a circle, about 1” in diameter, of hot glue around the hole of the metal lid. The glue should be on the inside of the lid now, the opposite side of the rubber coil. See image. Once the hot glue circle is in place, quickly attach the 1.5” balloon circle to the glue and press down all around the circle to make sure it sticks to the glue in all places. Once it is dry a little more hot melt glue can be put on the outside to better hold it in place but don’t go crazy with the glue or it could cause clearance issues with the impeller.
11. Make sure all hot glue is dry before attempting this step. Apply some petroleum jelly to the motor shaft and insert it into the rubber coil. You will see it push on the balloon piece on the other side. Take a needle and touch it to the tip of the balloon where it is pushing out with the motor shaft. We are trying to make a hole in the middle of the balloon, but we want to make a very small hole which is why we are doing it this way instead of just poking the balloon. Once the small hole is made push the motor shaft through the balloon. – see image
Step 7: TESTING, TESTING.
12. Now for a real test. Put the impeller onto the tip of the motor shaft. Just enough so that it stays in place. Now try to apply power to the motor and see if the impeller spins freely. A couple things can go wrong here. The motor shaft may not spin freely due to lack of lubrication on the balloon end or the rubber coil end. Also, the impeller may be touching the metal lid or balloon and wont spin freely. Find where your sticking point is and try to remedy it. I have found that adding extra voltage to my motor will sometimes “free” it up enough to spin from lubrication problems. And bending the impeller away from the lid can help also.
13. Once the test above is complete we can try the next test. Remove the impeller from the motor shaft. Fill the jar ½ way with water and put the cap back on. The cap should have the rubber coil and balloon installed and also keep the motor in place as well. Once the cap is on tightly, flip the jar over slowly and look for leaks. When I attempted this test, mine leaked a little so I had to redo my rubber coil, so hopefully that doesn't happen to you. My second rubber coil was perfect, not a drop of water escaped during this, or any other, test. Hold the jar upside down for at least a minute before you progress to the next step, we don't want to get anything wet if we can help it.
If you like you can try this test again with the impeller on and then add power to the motor to see it working as a “tornado machine” See pictures. When the tornado starts to spin it pulls air into its vortex, this can create negative pressure inside the jar. The negative pressure inside the jar makes it unlikely that it will leak during the tornado but after the tornado stops it could leak if a pressure differential was created inside the jar. Our waterproofing measures hopefully stop this from happening.
Now that we have tested that the unit is holding water without leaking, and the impeller can spin freely it is time to move on.
In this step we will permanently set the impeller in place so be sure all the waterproofing is done before moving on.
14. Due to the range of epoxies or glues that can be used I will simply state for this step that you should mix your chosen epoxy or ready your glue. Mine is Super Glue brand 2 part quick-setting epoxy. I mix equal parts of resin and hardener on a small paper plate and mix with a tooth pick. Then dab a little on the motor shaft and place the impeller onto the shaft. Then dab a little more onto the top where the motor shaft meets the impeller. BE CAREFUL NOT TO USE TOO MUCH EPOXY. If the epoxy runs over and sticks to part of the motor or lid it will be very hard to remedy it when it is dry. See image.
Once dry put a dab of hot glue onto the epoxy, just in case the epoxy isn't waterproof.
Follow the images for this step because it sounds tricky even though it is easy.
15. With the jar sitting on its base like normal, and the motor/lid assembly attached, lay a rubber band over top of the motor. Using 1 hand hold both sides of the rubber band down, this will put a little downward pressure on the motor. Now take a second rubber band and fasten it over the first. - See image.
Then, take the 2 sides of the first rubber band, which you should still be holding and curl them up and around the 2nd rubber band, then put the toothpick/skewer through the 2 available loops. -See images if this description is lacking.
16. With the skewer holding the rubber band in place, add a dab of hot glue to the ends of the skewer, over the rubber band to hold it in place. Then snip off the excess wood.
Now to prepare the stand for the tornado machine.
16. If you are lucky like me and kept the container we used for the impeller it will make a great stand. As long as the opening of the HDPE container is large enough that your jar lid can fit in it. The added bonus of using this plastic container as the base is, if the "TORNADO MACHINE" ever leaks, it will go right into the plastic container and won't make a mess. -see images.
17. (OPTIONAL) Hook up the LEDs as shown in the image. and hot glue in place.
18. Take the negative wire from your LEDs and run it to the - or negative of your motor. Take the positive wire from your LEDs and run it to the + of your motor. (most motors don't care about polarity, where the + and - go, but mine had a capacitor on it which does care about polarity so I obeyed the law.) Be sure to run the wires from the LEDs out the top of the container to the motor that way when you go to set the jar on top of the HDPE container the wires won't be in the way.
PRO TIP: To find the correct resistor for your LEDs. Take the number of LEDs you will be using multiply that number by 2.5 and subtract that total from the voltage of your power supply. Now take the total and divide by .02 This will be the smallest size resistor that you should use for your LEDS.
SO if you are using 2 LEDs like me. 2*2.5 = 5
Now I subtract 5 from my power supply voltage of 12. 12 - 5 equals 7.
Now take 7 and divide by .02 7/.02 = 350
SO 350 ohms is the smallest resistor I should use.
I used a 470 ohm resistor just to play it safe. HOPE THIS HELPS! IF YOU HAVE QUESTIONS DON'T HESITATE TO ASK.
Step 11: Where to Go From Here.
Do you have questions, comments, improvements? Let me know in the comments below.
I was thinking about where the tornado machine should go from here. I have yet to design a tornado machine 2.0 but if I do I would like some of the following.
-RGB LEDs and a micro-controller to choose precise colors for every occasion.
-Larger components. Powerful, high speed motor and custom laser cut impeller.
-Better looking base/housing. Probably made from clear lexan. Because I am familiar with shaping and molding this material.
-Micro-controller programmed to vary the "weather". Could be set up to vary the speed of the motor quite easily by using a high power transistor and a bit of code.
These are just some of the improvements I thought of, let me know what you build or come up with.
Runner Up in the
SciStarter Citizen Science Contest
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