Introduction: Desktop Fire-Tornado

Picture of Desktop Fire-Tornado

Use caution when working with fire and flammables!

I recently placed a meat thermometer next to the acrylic cylinder. It's temperature was starting to exceed 190 Degrees F. The acrylic that I was using was regulated for up to 170 I believe. With that being said I would not run this to long unless you have a cylinder material that is more resilient to heat (glass).

In the clip below there are two setups. I will have more details about there differences at the end.

This is an adaptation as a result of a demonstration that I put on for my professor and fellow students in class during Bellarmine University's MAT program. I had seen many fire tornadoes where you spin a lazy suzanne (or that alike) with mesh around the outside. I didn't like the idea of spinning the flammable liquid (alcohol). A quest for a safer method then ensued.

Through much trial and error, lessons learned, and a lot of curiosity; I have built something pretty cool.

I hope you enjoy this build!

Step 1: The Parts

Picture of The Parts

This items list includes a lot of the items that I did use and some items that I wish I had used. Some of these items you might have laying around the house.

Acrylic tube $15

Push button: $0.66
Manufacturer Part Number (digikey) GPTS203211B

Computer Fan $2.99:

Computer Fan Grill Screws: Not sure, these may come with the grill or the fan. My fan was left over from an old tower computer.

Fan grill: $1.66/grill (pack of three)

Metal Can: $0.77

Metal screen home depot $8.65:

9 volt conector/9 volt sleeve: $2.91
DigiKey manufacture number 1290

Cabinet Bumpers: $2.97
Home Depot- Shepards Self-Adhesive Vinyl

Step 2: Make a Stand

Picture of Make a Stand

This is the stand in which the pineapple can that I cut in half will sit on. I used two paper clip to give the can some support if the device is ever moved. The more centered the can, the more uniform the vortex.

I choose to bend mine slightly in to give more of a pinch to the can.

Step 3: Support for Cylinder

Picture of Support for Cylinder

The wire mesh serves as a support for the acrylic cylinder. The mesh is 8 high by 34 wide. The squares in the mesh are 1 cm by 1 cm.

As you can see, I left extra to use as hooks when attaching to the grill and to itself. When I make my next one I plan on having alternating squares at the bottom to attach to the grill.

Step 4: Attach Fan

Picture of Attach Fan

Using the fan screws, attach the grill to the fan.

Step 5: Fan Stand

Picture of Fan Stand

The height of the fan above the ground was determined by trial and error. For this fan the height was optimal at three cabinet bumpers high. At the end of the article I will talk more about considerations to make.

Step 6: Wire It Up.

Picture of Wire It Up.

Through my minimal research I found that it is best to have the switch on the positive wire. This is what it looked like before I cleaned it up. Before I started cutting the wire down I wanted to make sure that everything was working properly. It was so I shortened up the wires and hot glued the batty mount and switch to the side.

Step 7: Pour, Light, Flip

Picture of Pour, Light, Flip

I always remove my can from the assembly before adding the alcohol. I don't want to risk spilling inside the fan.

Step 8: Creators Notes

Something that I started looking into was the Cubic Feet per Minute (CFM) that the fans crank out. In the video you see that the one on the right (black) is rising up out of the cylinder. This fan (black) is able to crank out 64 CFM. With it being so powerful I had to decrease the amount of air that it was able to get. Therefore, I lowered the height by one cabinet bumper. In doing so, I was able to stabilize the vortex. I did research on the blue fan and couldn't find any literature on it. The blue one is nice because it is quiet. The black fan is nice because it creates a huge flame. However, the black fan is quiet loud and can be distracting if this is a decoration item sitting off to the side.

After use, the acrylic cylinder gets hot, real hot. I don't know if there is a work around for this or if it's just the nature of having a heat source inside a container. Some thoughts are decreasing the width of the internal container that is holding the alcohol. In doing so, I am guessing that the further the flam is from the walls the better. However, the ratio of width of outer cylinder to inner can my create some issues.

As I continue to make new ones I will update this to let you all know the best design and practices that I come across.


文邱 made it! (author)2015-02-19

This is my Desktop Fire-Tornado.

Kinnishian (author)2015-01-21

Perhaps you can direct some of your air onto the exterior of the acrylic housing. This should increase conduction away from the plastic tube while being possible to incorporate relatively smoothly to the design.

tervuren (author)2015-01-06

As one other person suggested you may want to use pyrex or something else that can withstand high heat, such as material for fireplace door, or for kerosene lamps or lanterns to use it safely, plus keep in mind this concept and project is using a phenomena called chimney effect, which can reach rather high temperature in short span of time, if not careful can pose high risk, for sure fire hazard, no matter what fuel you use, think of a jet engine afterburner.

but nonetheless it is cool idea.

DaveT2 (author)tervuren2015-01-15

Be aware, BTW, that Aladdin kerosene lamps, which use such a chimney, are known to be capable of doing exactly what tervuren (are you as intense as the wonderful dogs of that name?) alludes to: suddenly emitting a three foot flame and setting the ceiling on fire.

What happens is the the lamp actually becomes a blow torch because the kerosene reservoir has gotten too hot. That could easily happen here, so make sure you have the fuel source adequately insulated from the flame.

Or use a metal cylinder and do it on purpose. A DIY jet engine.

gzus11 (author)2015-01-06

i built one with no moving parts. using the impeller disk from an old hoover motor at the base of the tube encourages the rotation of the air as it enters. with the alcohol burner just below the disk generates a nice tornado flame effect.

omikeo (author)gzus112015-01-06

yeah i like the simpler aspect can you post a video ?

gzus11 (author)omikeo2015-01-07

no video, but there's some photos from my experiments

Dandeman321 (author)gzus112015-01-10

Ooo, do you have a video of that thing working? The third picture? Looks pretty nice!

gzus11 (author)Dandeman3212015-01-11

that's burning a chafing gel. I found the alcohol fuel with some wire wool performs better.

rjones39 (author)2015-01-10

not an indoor toy

Bowtie41 (author)2015-01-08

Like you,I REALLY like the idea of NOT having a dish of spinning fuel sloshing around.Great Job! I gotta build one of these for sure.After looking at other vids on YT,I found this one that tells you how to color the flames.I'm gonna try it with your project:

Borax/Boric Acid for green,strontium for red,and potassium for violet(Boric Acid I got,but have to figure out where to get the others)

If you use zinc oxide it turns it pink, zinc oxide and sugar

Fastaco226 (author)2015-01-04

Ok I'm a little ignorant in the field of burning things but did you put the alcohol into the can and just light it? Wouldn't it all burn instantly and not a slow burn for the tornado to take effect?

PhillipS1 (author)Fastaco2262015-01-06

Volatility is measured as a chemical's ability to evaporate quickly. The vapors are what interact with the oxygen to create fire, and the fire accelerates evaporation, but it does not do so in an instantaneous manner because alcohol is not as volatile as something like TNT. So the vapors coming off the alcohol fuel the fire gradually over time as the liquid evaporates in the chamber.

antotabo2 (author)PhillipS12015-01-08

You are mostly right exept your analogy. TNT is not a fuel like alcohol but rather a perfect mix of fuel and oxidizer, therefore it doesnt need oxygen for combustion and therefore doesnt need to evaporate like fuels.

jkinsman (author)Fastaco2262015-01-06

If you soak cotton balls with the isopropyl alcohol then light those on fire they will burn slowly

mjursic (author)Fastaco2262015-01-06

The alcohol will only burn on the surface, where it comes into contact with oxygen. That's why you'll get a slow, even burn. You can get pyrex cylinders at your local surplus shop. Or at least in mine--Active Surplus on Queen Street in Toronto has them for decently cheap.

AlanC2 (author)2015-01-07

There are a few portable campfire stoves, both here and on Youtube. Two soda cans, spliced together holding cotton balls, and a series of small nail holes for the flames. Smaller, multiple flames may be what you are lookiing for - longer lasting and less heat.

eclectic99 (author)2015-01-06

If you want to study airflow based on fan rpm rather than changing the height of the air input space, a cheap add-on is a PWM DC controller. I use one on a similar fan unit for another application. There are cheaper ones than the one cited below with lower current ratings as well.

Mine is:
6V-90V 15A Pulse Width PWM DC Motor Speed Controller Switch ~$7.50

PhillipS1 (author)eclectic992015-01-06

You could go even cheaper and just wire a potentiometer on either side (positive or common) of the power supply and dial the resistance up til you get to the desired flame height. Computer DC fans can operate under variable voltages and do not require PWM to slow them down, though that is still a viable albeit more expensive solution. The PWM method would also decrease duty cycle and power consumption, while a pot. would merely release wasted energy as heat, provided that the controller itself doesn't consume a larger amount of energy. Which one is better suited to the battery would be hard to say without some precise measuring.

Arx (author)PhillipS12015-01-06

Most pots are rated for very low power. this would only work for very small fans, or large pots.

starphire (author)PhillipS12015-01-06

Computer fans are driven by brushless DC motor control chips, so below (or above) a certain intended operating voltage they will not work at all. Under battery power the adjustment of a series connected pot would have to be tweaked as the battery voltage drops to maintain the speed. The other great advantage of PWM control on all kinds of DC motors is that they drop speed without also significantly dropping torque or efficiency. PWM controllers are getting so cheap anymore (I've seen $6 for a complete module with trimpot controls, for small motors), the extra cost should more than pay for itself in batteries saved before long.

MT1 (author)2015-01-06

For the tube heating problem, is there a way to divert some of the fan flow to the outside of the tube?

ToddT (author)2015-01-06

Now that is what I can call totally cool!

eclectic99 (author)2015-01-06

In addition to Doug Gault's suggestion: Corning Pyrex glass Bake-a-Round French Bread Tube is ~4" x 14"

or Quartz Glass 50" x 4" (cut to length and make a few more.

Both would require a redesign since they are 1" larger diameter than your setup.

But what is of interest to me is the fuel. It appears you use 91% IPA from photo. Did you try ethanol? Results/comments?

There are many types of ventless fireplaces these days burning 100% ethanol. I am confused though since alcohol (in the US) must be taxed as a 200 proof liqour if there is no dentaurant in it. Is this fuel overpriced as "burning taxed liquor"? or just more expensive than petroleum based ethanol due to the azeotrope issue with purifying bio-based alcohol?

Anyway, i would be interested in fuel type vs. flame appearance/duration comparison in a future update.

BTW, thanks to phillipS1 for the potentiometer suggestion/explanation.

richknitter (author)2015-01-06

I purchased this for the tube:

It was $25 on ebay, but I think it will withstand the flame better.

schumi23 (author)2015-01-06

I really like this. I do believe I might make this.

One point:

In the clip below there are two setups. I will have more details about there differences at the end.

It is the differences of them, so their.

The Green Gentleman (author)2015-01-06

Wow. That is just really cool. Twisty


BurgersBytes (author)2015-01-06

I think it would be a better idea to add a second clear cylinder outside of the other so that it does not burn somebody seriously!

ajarworks (author)2015-01-06

Nice. Nothing so much fun as playing with fire :-}

A thought; have you tried introducing some copper wire into the flame? Trace amounts of copper give a green tinge to flames.

MPLS_CBG (author)2015-01-06

Maybe double wall acrylic tubes with water inside. Might need to be a bit on the wide side to get an evaporative cooling effect but hey more physics.

zacker (author)2015-01-06

how about using a glass cylinder like you have, then putting it into a bigger diameter glass cylinder, so its basically, inside a glass protective tube. Maybe the outer one wont get so hot if there's like an inch or so of space around it and the inner class cylinder. This way if someone touches it, they wont get burned.

DaveT2 (author)2015-01-06

Great idea! Anyone who wants to try this with a Pyrex glass cylinder, such a thing is easily available as a kerosene lamp part: a cylindrical chimney. For example: Less than $11!

Other shapes are available that would be fun to experiment with. What would a standard lamp chimney, or a cylinder with bulge at the bottom, do to the vortex? I actually have a couple of different types; I may give this a try! One thing is for sure: you'll be able to run your vortex forever without worrying about heat.

Might also be fun to try this with an old blender. Use the blade fitted to the cylinder to spin up the vortex. Just do it outside!

Hal Nine Thousand (author)2015-01-04

Perhaps glass cylinder vases, just cut the bottom off with a glass cutter?

I would be very leery of using a common glass vase and cutting the bottom off. You'd run the risk of small fractures in the glass from the cut expanding from the heat, and the whole thing falling apart unexpectedly.

Doug Gault (author)2015-01-02

Cool is Cool! I'm a bit concerned about the acrylic melting. Now many moons ago (70's) you could by a bread baking kit which utilized a Pyrex cylinder, and you can still purchase these on Ebay, on the cheap. As I saw several up for sale recently.

With that said, it's time to burn something up. Yeah I can dig it now. . .

pellis3 (author)2015-01-01

a Pyrex cylinder would be a longer lasting solution. they are pricy though.

james14th (author)2015-01-01

Great project.. For Science science teachers..lots of physic lesions and I found.. When ever you can blow something up or have visible flame you have your students complete attention..

dbaldauf (author)2014-12-31

To help with the heat, this could be done with a double wall. One being the normal wall containing the airflow and flame with a thin space between the second (thinner outer) wall.

enelson8 (author)2014-12-31

I was thinking, "hmmmm... I've seen this before.." But than I saw it was desktop sized, I love it!!! Now all I have to do is convince my parents to let me have Fire in the house... Any ideas? haha!!

ZiggzaggZebra (author)2014-12-31


SphereX (author)2014-12-31

Excellent presentation! Like the use of common day items. Maybe you could score a glass cylinder at hobby lobby or Op shop.

kbc2 (author)2014-12-30

very cool! Question though, what about oil burning lamps? I had a tiki torch with a "hurricane lamp" globe over it, about half an inch clearance between canister and globe, a nice breeze blowing, and it made a much taller flame. Not a tornado effect, but was a cool effect. Most acrylic can withstand the heat for some time, not very long though. I have seen some tempered glass cylinders on eBay which would be much better for longer burns.

Involved Observer (author)2014-12-30

Fun instructable, can't wait for the updates! Good job!

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