Build an Amazing Tesla CD Turbine

Step 10 How Fast Can It Go? ...and A Safety Reminder.

Everyone wants to know how fast it will go...that's natural in our fast-moving world. But keep something in mind...to set speed records with this tiny, but powerful, device requires a special test zone, preferably not in a populated area!

CD's will explode when over-revved. This includes any RPM over 20,000 rpm. It is unlikely that more than a couple thousand rpm will be achieved by ordinary water pressure. (1400 rpm was max with my last test on water pressure).

But, again, I must stress that this innocent-looking machine becomes a screaming demon when powered by high air pressure. The CD Turbine, with 120 psi straight air pressure, will easily exceed 20,000 rpm and will violently explode the CD's in the Disc Pack. Not maybe...it will for sure. Don't use air pressure unless you are completely aware of this!

I use an air pressure regulator, digital tachometer, and a bullet-proof enclosure for high-rpm air pressure testing. And all the usual self-protection gear for dealing with sharp shrapnel.
So, be careful, wear protection and have fun!

Oh, by the way, the CD Turbine, with the plain Disc Pack has gone 14,500 rpm on half-throttle compressed air, smooth and safe!, and 11,000 rpm for the Magnetic Disc Pack. So far, so good!

I'll show more secrets in the next Instructable of the amazing Tesla CD Turbine.

UPDATE: see my latest instructable for lots more CD turbine fun, with the new Kitchen Sink Model.

Comments

[pilotgabe]

I am amking an air powered version and just to be on the safe side what is the highest PSI can i go up to with out causing a blow out and injuring me or other materials around me? Thanks if you can let me know!!!

[mrfixitrick]

There is no safe psi. You have to build a protective cover or barricade, with the assumption that the turbine unit will blow up. I use either a one-foot square polycarbonate bullet-proof box for such experiments, or an 1/8 inch steel barricade to hide behind. Gloves, glasses, and heavy garments are also recommended.

What happens is, if the turbine is working properly, even 15-20 psi is enough to send the discs over 10, 000 rpm. With excessive rpm, the CD discs can fracture, and sharp shards come through the side of the case, with possible injury or death.

I have taken turbines up to 14,500 rpm, but they will usually break before that. The magnet spacers limit the max rpm. Plain CD discs go up to 25,000 rpm before exploding.

The CD case itself can take up to 120 psi without exploding...as long as it is somewhat gradual. I did blow up one turbine by too rapid of an increase in pressure! ( see "Tesla CD Turbine Blender Bursts On Kitchen Table",  http://www.youtube.com/watch?v=EXo3e58rZ7U  )

[pilotgabe]

THANK YOU!!! this is the much needed info i need now with the turbine disks its self is there a great design on how to cut the disks to make holes in the blades or is that a dangerous way to "frag" the disks Iwant to use the magnet idea and also incororate this turbine design into a future jet model that i want to build so anything you got on this?

[mrfixitrick]

The polycarbonate CD discs are a weak point for a high-speed Tesla Turbine. (and Tesla Turbines do love to rev up to make power!)

CD discs with magnets are limited in rpm to about 8000-10,000 rpm. Even then, the disc could shatter at any time.
Cutting holes in the discs could lower the safe rpm even more.

When a disc blows at 15,000 rpm or more it literally explodes and sends sharp shards in all directions. See this site, "The Case Of The Exploding CD-ROM Record",
http://www.qedata.se/e_js_n-cdrom.htm

Another helpful hint...When building a turbine case or parts use polycarbonate or aluminum or steel, etc. Don't use acrylic. Here's why: http://www.youtube.com/watch?v=Hsls5ZPCUnE

So, the idea is to keep the revs down and play safe with protection. New materials such as carbon nanofiber ceramic for discs, and lighter, stronger magnets will soon make the magnetic Tesla Turbine a greater reality.

[pilotgabe]

again there thank you for the info you are giving me! I was also doing experiments and was also making aluminium foil disks and other material as well. but safety is always a factor or the number one priority that i do. So yes i am being safewith this.

[mrfixitrick]

Ok, now that safety is covered, I'm happy to answer any other questions you may have on Tesla disc turbine construction or running!

[fairbanksd]

Very good safety points on RPM limits with typical CD's . Has anyone tried to build the same tesla device using super balanced disc from a hard drive? I believe these could be suitable and carefully machined to boot.

[mrfixitrick]

Here's a couple of Tesla Turbine instructables using hard-drives for discs:

  http://www.instructables.com/id/Tesla-turbine-from-old-hard-drives-and-minimal-too/

http://www.instructables.com/id/Build-a-15%2c000-rpm-Tesla-Turbine-using-hard-drive-/

[mortal101]

Instead of using CD's what about the aluminum discs found inside hard drives? They would be smooth & balanced while possibly not exploding at 20,000 rpm.

[lawn_mower_man]

Dose it have to be cd's? Can it be about any strong light weight object that has about the same dimensions and weight, like card board or realy thick card stock? and if so can it run at the high rpms like the cds but with out breaking?

[mrfixitrick]

 People have made Tesla Turbines out of paper.

The paper discs should be stiffened by using something like Crazy Glue, or they will simply move to the side when high-pressure air from the nozzle hits them. They will not withstand high rpm's like a CD, and would be hard to balance.

Note that CD's are dangerous at high rpm, especially with magnets attached like I do. You MUST have a polycarbonate (bullet-proof) case, or a steel enclosure, to run a Tesla Turbine at high rpm. That's why I recommend water pressure turbines for most folks.

[Nicholai]

i would prefer to build this in a piece of metal pipe and use sheet metal instead but the pipe would still be a good limiter on the frag grenade that this is when high pressure air is used i was wondering how high rpm would 10 guage sheet steel be able to withstand before shattering, is there anywhere this could be tested safely (excluding fallout shelters and tanks)

[manicmonday]

Your using magnets on disks. Why not add wire coils to produce electricity? Obviously any connections would have to be dry, but I wonder how water would effect magnetic flux and the ability of the coils to absorb that flux.

[mrfixitrick]

Yes, I have added coils of wire and have been able to light an led, for example. It could a great design for a turbo-alternator. It woulld be much more efficient if the top magnets were oriented with N,S,N,S,N,S instead of the N,N,N,N,N,N that they are currently to engage the magnetic coupler. I don't think the water would affect the flux much. The coils can be outside the case instead of inside, and all wiring would be dry. Also consider that the coils can be pulsed with electricity to cause the discs to rotate, making the Tesla Turbine into a Tesla pump!

[LegendaryPrimate]

A further question regarding electricity: If I were to use a magnetic disk pack for the turbine, could I hot glue a copper coil to the top of the CD case and attach leads to generate electricity?

[mrfixitrick]

Yes, that will work. An iron core will make the output stronger. Alternating the magnets NSNSNS will be better than the NNNNNN that I use. Then it will generate AC, rather than a pulsed DC current.

[seabeepirate]

Does using more CDs create more torque? I'm considering building one of these to produce 12VDC power similar to DIY wind turbines. I have several designs I'm considering. I'll have to do research of my own obviously, but I've considered collecting rainwater from the gutter spouts of my home (or camping cabin) or diverting water from the small river that runs through the back of the camping property. I've also considered using a large conical wind collector to provide pressure to the nozzle. I'm afraid that the fluctuation of the wind speed may be a problem, and I'll have to do quite a bit of research to see if I can build a self regulating collector (possibly by means of an over-sized collector with a blow off valve?). This concept has actually renewed my interest in green power. It just so happens that I have 90% of the parts I need to build this (unfortunately it may mean sacrificing a spindle or two that I current use as CD cases). Where did you buy your magnets?

[mrfixitrick]

Glad to see you are interested in the Tesla Turbine.

The Tesla CD Turbine is a pressure turbine and requires a minimum of about 20 psi pressure at the nozzle before it can begin to do any functional work. 80 psi would be best.

You won't be able to get enough pressure with a downspout, unless it was several stories high. (approximately .5 psi per foot of elevation.) Same goes for the river...You would need a 30-40 foot vertical height of water (*head") just to get things going, 100 foot vertical for decent performance.

More discs will provide more torque, but fluid velocity is the most important factor.

Same problem with air...lack of pressure. Making a cone won't increase it much...You would have to come up with a system that increases pressure for part of the fluid, while utilizing the lower pressure to do so. A Ram Pump does this for water, for example.

I get magnets from this link at K&J Magnetics

I can't see spinning a metal object creating a magnetic field in itself, but if a metal object is spun in a magnetic field, it can behave as if magnetic. And a spinning magnetic field like the CD Turbine can cause a metallic plate such as a pie plate, to spin. What happens is there are eddy magnetic currents formed in the plate from it's interaction with the turbine magnets, pulling it around.

We tried a CD disc in the following movie and it didn't spin in the magnetic field of the turbine. I tried it later and was able to get a very slight spin effect. The foil is very thin!

See this video.

[seabeepirate]

I just thought of something else to add... I've heard (but never tested) that spinning a metal object, even without magnets attached, creates a magnetic field. I wonder if the thin foil layer of a CD is enough to create this effect.

[seabeepirate]

Goodness my creative juices are flowing now... again something else to consider. With the magnetic coupler, how difficult would it be to gear it down for higher torque with lower RPMs? More than 80% of electrical power worldwide is produced by turbines(mostly steam turbines, the steam is most commonly produced by cole burning, solar collection, or nuclear reaction, yes that's right everyone! Nuclear power plants are actually steam power plants.). These turbines spin at incredibly high speed for higher efficiency(turbines are horribly inefficient at low speeds) and then geared way down. Is the magnetic coupler rigid enough to replicate(on a smaller scale of course) this design?

[mrfixitrick]

Haha, gotcha thinking, eh? Good! The magnetic coupler could conceivably be geared down using a magnetic gearing system. The six top drive magnets could engage 12 magnets in a twice as big of radius disc. However torque might be a problem because of there would be only one or two magnets engaged at any time, compared to all 6 normally. You could use a worm-gear or toothed belt pulley system for gearing as well. Keep in mind that this turbine has a very limited top speed because of the CD's and the magnets. Approximately 10,000 rpm would be a working upper limit, compared to 20,000 rpm for plain CD discs. The turbine would prefer to run in the 30,000 rpm range for best efficiency, and proper stainless or carbon-fibre discs would be appropriate in that case. A direct-drive high-rpm alternator would be one solution. A normal auto alternator could handle 10,000 rpm or more as well.

[randomray]

Could you use steam ? I believe Tesla intended to make steam generators ? They would have been far larger of course .

[mrfixitrick]

Tesla's turbines were mainly designed to be used with high temperature, high pressure steam. A turbine the size of mine was made by Tesla and developed about 30 horsepower at 30,000 rpm. A slightly larger 8 inch turbine was his smallest in production, and it was 110 horsepower. Tesla made turbines up to 5 feet in diameter, and tested them on compressed air, steam, mercury, and many combustible fuels such as even...gasoline! It's interesting that the Tesla Turbine has recently been proven to be the only turbine design that to be able to run on 100% biomass combustion gasses.

[Shwaman]

can this be put in line on car exhaust to generate electricity ?

[mrfixitrick]

Yes and no...if you were to mount this in-line in the car exhaust, it would generate too much back pressure through the 1/8 inch hole the gasses would have to pass through. And it would only work for a few seconds before the hot-glue melted, CD discs warped, and the case blew apart! However, if you could cool the exhaust gasses enough, and enlarge the turbine nozzle, yes this little CD Turbine could actually work to generate power. You could also build a proper Tesla Turbine from high-temp stainless discs and metal or ceramic case, with a shaft-mounted alternator and use that in-line with the exhaust. With a good design, it could replace both the muffler and the catalytic convertor and have less emissions.

[Shwaman]

right. I meant a proper version :) I am doing a project for school and hoping to use a similar design to yours, but we are working with wind power ( mounted to the top of a moving car. I want to scoop the wind with a 3' wide mouth plywood structure and push it through a funnel and 1/4" tubing system into a few inflation needles (for basketballs ) I am hoping that this will give me sufficient PSI at 30 mph. whatdya think?

[mrfixitrick]

The psi pressure won't increase much by using the tapered scoop. It will smooth the flow and increase the velocity of the fluid to a point, but the increased resistance of the smaller tubes will negate even that. You won't get more than 1 psi of pressure, which is not enough to run a Tesla Turbine. It will, however, run a paddle or propellor type turbine or generator. The Tesla design relies on a high pressure difference to extract the kinetic energy from fluid as it moves across the discs. It must rotate at high speeds to be efficient. I can't see that happening with the Tesla Turbine car-top set-up. You need a vane type or propellor type system. Here's a suggestion... Use a 12-volt radiator fan. Most any vehicle will work; some have a smaller footprint, and power rating, than others. Mount the fan in a duct on the roof (perhaps incorporate the original fan cowl) and hook up the fan to charge a 1.5 - 6 volt battery when the vehicle goes fast enough. Note at slow speeds that the fan will turn from the battery and actually help propel the vehicle forward to a very small degree! (a circuit could be used to prevent the draining of the battery in this way)

[Shwaman]

Thanks, that's the info I was looking for. I won't get the psi I need, so I will go in a different direction. - I really enjoy your work. Thanks for taking the time to share so much and answer questions.

[randomray]

Pretty cool . As for using gasoline the scariest thing I read about was using it for a "steam "launch .They burned the gas to heat/vaporize the gas in the boiler to run the "steam engine ".Now, it just sounds insane but ,it went into production for awhile .It can't have been long , that was a accident waiting to happen , burning gas in 1880s tech. in a wooden boat .

[mrfixitrick]

Perhaps we haven't progressed that far...automobile fires currently cause over 500 deaths each year in the US ! (still burning gas...except in plastic cars now)

[randomray]

Let's see gasoline "petrol for our British friends " is flammable , explosive ,and a known carcinogen and it just smells bad and we drive our autos around with it under our seats . How's that for living your life on the edge . Kind of gives the whole alternate fuels thing a different perspective .I work at a refinery and one of the new engineers was giving a talk about safety and said if we just now decided to use gas to power something it wouldn't pass any reasonable safety regulations . It's just grandfathered in because everyones been using it for over 100 years .For the nit pickers out there I know different types of oil have been used for yes , thousands of years .Drive safely !!!

[mrfixitrick]

Good comment... I have recently become allergic to gasoline and oil, and consider them the scourge of the earth. I've lost the ability to use my hands for work and my job of mechanic because of this. Fortunately, mankind's current love affair with oil will soon seem like a just a passing one-night stand. I think Tesla technology will have a big part to play in the transformation about to take place, and that is the big reason why I dedicate my life to promoting Tesla tech!

[kusrox]

is there any way the torque could be measured for the turbine?

[mrfixitrick]

Good question! There are many expensive options for measuring torque, including wireless units that will transmit to a computer. However, having no money, I attempted to measure torque with a simple pulley and string method. It's not very accurate since it only measures low rpm or starting torque. Basically, I wrapped a string around the magnetic coupler on top of the turbine, and ran it through a small pulley to the floor. Then I hung weights off the string until it could be lifted by the turbine. I think it ended up being about an inch-lb of torque with 25 psi faucet water pressure.

[kusrox]

is there any way you could send me pictures of this please? im having a hard time visualizing it.

[mrfixitrick]

I can't do that right now, the CD turbine blew up and the magnetic coupler is joined to the blender.

However, have a look at the picture below, and visualize string wrapped around the coupler on top of the turbine.

The string goes out horizontally to a small pulley, say attached to the back of a chair, and from there down to the floor.

At the floor the string can be attached to a bag with coins or weights for "ballast", to be raised by the turning of the turbine.

The radius from the center of the coupler to the string wrapped around it, is multipiled by the bag weight to get inch-pounds (or inch-ounces) of torque.

[kusrox]

just trying to get this straight: the string is wrapped around the outside of the coupler (like around the magnets)?

[mrfixitrick]

That's it exactly. Then out to a pulley, and down to the bag of weight on the floor. You can do a static or dynamic test. Static test would be the weight that allows the turbine to just barely start to rotate. (note: weight x radius gives the torque) Dynamic test would be the weight that allows a constant rpm at the turbine. (That way a torque at a certain turbine rpm can be roughly obtained). Dynamic is trickier to measure than starting torque! So start with starting torque...hehe

[astrozombies138]

If i am building the magnetic coupler in your turkey time instructable i dont have to make this right?

[mrfixitrick]

The above picture is for the magnetic coupler I used in the PumpkinCutter turbine. The turkey time turbine magnetic coupler has CD discs on both sides of the magnets. Either one could likely be used. Good luck in turbine building!