Simple coke can engine

This is a simple coke can Stirling engine you can make in under an hour. No epoxy or RTV needed, just super-glue. It's all supported by steel wire, with spade connectors for all of the bearings.

Important note: It has been found that aluminium drinks cans need additional cooling around the top because the aluminium is so thermally conductive. Use steel cans if you can, such as Pepsi, Tango etc. Scraptopower has many other plans for simple Stirling engines, have a look here.

Thanks to David Williamson for the diaphragm design/ construction method. Check out his website here!

Materials1 Coke can

• Steel wire wool
• 1.6mm steel wire
• Spring paper clip
• Normal paper clip
• 0.4-0.6mm fishing line
• Super glue
• Thin cardboard from a cereal box
• A balloon
• 6.35mm electrical connector/spade connectors .

Step 1: Open the can with a can opener

Open the top of the can with a can opener.

Comments

[pastorkirbyjohnson]

Middle School Science Fair, here I come!!!!
Awesome!
I had never even heard of a Stirling Engine until this instructable.
My kids and I will have a blast (in a good kind of way) with this.

[8v92]

Trying to figure out why this engine runs is like figuring out why a bumble bee flys, it should not run but it certainly runs quite well. The counter weight in the center seems to resonate and the flywheel is low mass but high inertia. I am not an expert but there are principals at work here that need to be studied. This is a great example of thinking outside the box.

[burnerjack01]

The principle is quite simple. If I may.... There is a displacer inside the can.
This displacer moves up to allow the air within the can to make contact with the hot can bottom. This expands the air which drives the diaphragm up due to expansion. The displacer then drops to the bottom of the can which insulates the air from the heat thereby allowing the surfaces not exposed to the heat to cool the air which allows the air within the can to contract.
The REALLY cool thing about sterling engines is if you drive the shaft instead of the other way around, it becomes a heat pump! Not bad for 1880's tech!

[burnerjack01]

I think it's AWESOME that you are introducing your kids to this!
Not only is this device classified as an external combustion engine and is truly a flex fuel technology which can even run on solar or geothermal heat.
In fact, any heat difference between the "hot cap" and "cold cap" will make it run. This goes all the way back to 1880's Scotland and I have read that it was devised to take the place of the dangerous steam engines used in coal mining at the time. Not a bad job of design by a monk of all people.
Ther is a wealth of history associated with this device.
One last thing, it has been said that this device is one of the most thermally efficient engines ever devised. Good luck with the Science Fair!

[rwcrocker]

Very cool! We built it today. It took a little more finesse bending wire than I had anticipated. If you don't balance it well enough, it wobbles like crazy on the wire legs even if you're holding the base.

We added a 15 mm strip of wet paper towel around the top of the can to act as a better heat sink - it helped a lot.
Thanks a lot for the great instructable!!

[scraptopower]

Wooo! First person to build this ? Please share some photo's if you can :)

The paper towel is a good idea!

Thanks!

[8v92]

I did not see the fishing line going to the displacer in the movie so I thought it was resonating somehow. I still think it is a good design and would work with multiple cylinders. Perhaps an affordable and practical vehicle could be built using a stirling engine.

[christpher]

I gust watched tow helicopters go by woooooooooow

[tojo13]

Where and how does the displacer connecting rods go?

[rikardom]

Awesome!

[tobune]

Very good concept. Trying to make it reality now.

[tokin]

Cool!

[mattle]

Yes it is!

[stumitch]

fantastic! i want to build one!

[teniva]

Just love it and I certainly must try it

[bhaskar0kumawau]

can i use a steel wire instead of fish line and tell me how it works??????

[begunia]

Amazing work my friend!

[kuruting]

Amazing...

[lepar]

Awesome work. Thanks for sharing it with the community.

[merkuri2]

Interesting I must say.Trying to make it now.

[kokina2]

You are awesome and creative!

[torina2]

Excellent work!

[Chowmix12]

I really want to do this project. I have all the things but the wire. Would paperclips work as wire? By the way, would a few drops of water make Stirling engines more effective? I know steam is 100 times the volume of water.

[scraptopower]

I wouldn't have thought paper clips would be long enough, even un-wound. You could try adding another coke can on top for the bearings like my other instructable "make a coke can Stirling egnine" . You can get this kind of wire at garden centres and the like, it's not usually expensive, don't get the really thin 1mm stuff though as that won't work.

My engines that have had small water leaks all splutter to a quick death, maybe it would work but you need to be quite precise in the amount of water :)

[Chowmix12]

the paperclips worked for the crankshaft, I made a flywheel of cardboard and glued it onto the crankshaft. For some reason I couldn't get the engine to work.. I gave up on it...

[sandra-1]

Very cool! We built it today.

[MCzone]

learn to measure
how does 15 cm get that far
you made me waste 30cm of wire.

[MCzone]

oh im sorry i made the mistake

[scraptopower]

Use it for the connecting rods.

[MCzone]

I started using it for the stand and the loop above the basket <:(

[wiinick]

I almost id that too, but my base looks nothing like the picture, but does it work, yes.

[MCzone]

I never did get that tin can working, but its cool

[nishi biswas]

I have tried to assemble a Simple Coke Can Engine, but after several attempt, I failed, so please let me know how would you help me if i become a paid member.

[scraptopower]

Authors on this site are not paid, so being a paid member will make no difference.

Which steps are you having difficulty with ?

[pauli2]

Amazing work have you done.

[scraptopower]

Thank you.

[antonio23]

I found this project very interesting! Trying to make it now.

[wiinick]

well i assembled the thing sadly it doesnt work, its my fault so i am going to see if i messed up with the counterbalace, and there maybe a lot of friction.

[joehudy]

this is probable a dumb question bot what does the displacer do?

[wanzaidi]

Hi every one,

I found this project very interesting. But one question keeps bugging me - why fishing line, not a wire as the conn rod for the displacer?

Wan
p.s. I will be making one soon.

[bryahn]

Sorry if this is a stupid question, but instead of a candle, could you heat this with say a wire coiling around the bottom 2-3 inches of the can? similar to say a water heater element maybe.

[melisa2]

You are great!

[wiinick]

hey, i put off this project for a bit, that explains the lack of a billion questions, but i was wondering if this may work, cuz i cant seem to find any other wire than hanger wire.

http://wiinick.deviantart.com/art/My-coke-can-flywheel-204305725

I was wondering if the 2 notches on the side, the cranks, if they are too steep.

[scraptopower]

The cranks for the diaphragm are way too big. They should be about a quarter of what you have. I doubt you'll be able to bend the cranks out of coat hanger wire, and even if you do, it won't fit through the electrical connectors.

Have you looked in some garden centres for the wire? That's where I buy it.

[wiinick]

i also figure since the diaphragm moves up and down further, that the size of the cranks would not matter, so u still think that it wouldn't work

[wiinick]

well that helps a whole lot, what is it called, or at least something to look for.

[scraptopower]

??? Steel wire it's called ?

[wiinick]

hah ok.

[tonyta2]

You are awesome!

[tonyta2]

You are awesome!

[wiinick]

where can i get these connectors, any other things i can use for this.

[scraptopower]

Go to an electronics store. I've tried bending the wire into to make the bearing point, but it had too much friction.

[wiinick]

Ok so radioshack and look for spade connectors.

[scraptopower]

http://www.radioshack.com/product/index.jsp?productId=2103314

[wiinick]

now, how did you get that wire so strait, mine comes in a roll, so its so bendy, and curved.

[scraptopower]

Just straighten it out with your hands, that's what I did!

[wiinick]

oh well ill figure it out.

[sharmarohit164]

what is the use of fish wire

[wiinick]

to pull the displacer up.

[wiinick]

Im sorry i keep asking and asking questions but here i go, i have the balloon over the can with the fishing line in it, now how far is the diaphragm supposed to move up and down, or is it supposed to move at all. with now candle on it.

[scraptopower]

It should move about 5mm at least, when you move the displacer up and down.

[wiinick]

Well thats a problem it doesnt move at all, ill see if the gaps are too big

[scraptopower]

What gaps ? Even with the worst possible displacer anyone could make, it would still move. There must be be an air leak somewhere ? What did you make the hole with the fishing line with ?

[wiinick]

Oooh, 5cm, you mean the displacer, i was talking about the diaphragm, how far is the diaphragm supposed to move, because i made a new diaphragm, put it on and used a needle (way better than a tac- cleaner hole) but still the diaphragm doesn't move, i think heat is the main factor. So am i supposed to pull the diaphragm tight or leave it a little loose to move.

I have no experience with sterling engines so this is why im starting simple, and working my way up.

[scraptopower]

Ok, leave it a little loose. I said 5mm btw not 5cm. Well if it isn't moving, what are you using to heat it with ? You are moving the displacer right to the top and bottom of the can right ?

[wiinick]

Good news, i put it over a flame and it started to move up and down, then put it in the freezer for a minute and it didnt move at all, so heat is a big factor in the movement, no the question is should i leave it loose and create a vacuum that sucks it down when not heated, its hard to explain, because with normal air in it, the pressure kinda makes it poof up a little, but with a little lack of air it will make the diaphragm go down further, do you get what i mean.

[wiinick]

Oh i see now, 5mm, oops, i am not heating it right now, and am moving the displacer up and down, im wondering if it should move without heat, because i dont think so. i could send you a pic if needed but i dont think thats it would be necessary as i have followed your directions quite thoroughly. Thats why i ask so much questions.

[scraptopower]

Just leave it a little loose the exact tension isn't super critical, it's better loose than tight. It's sounds like it's working fine so carry on building it. Oh BTW I just updated the first and last step with some new info. Just to say that steel cans work better. All the people who have used alu cans have had to add a wet cloth around the top to keep it cool because the aluminium is more conductive. So you can get a steel can, do that.

[wiinick]

I made a video at like 12 in the morning showing the diaphragm moving.

http://www.youtube.com/watch?v=JIA2vlvDZmM

[scraptopower]

It's perfect! Looks better than mine.

[wiinick]

good advice.

[wiinick]

I just read my last comment and it sounds really insulting ----(as i have followed your directions quite thoroughly. Thats why i ask so much questions.) I dont mean it like your directions are basic, i mean well, you know what i mean.

[wiinick]

well the balloon(between the plates) was causing massive friction with the fishing line, when i made a hole, using a tac ( just the tip), because it is elastic it would close up on the line. So i made some cutting and yes there is a small hole. Im guessing i should make a new one with a needle like you said?

[scraptopower]

You have to cut the rubber away around the hole for the fishing line :)

[wiinick]

How do i put the wire on, this page doesnt really go into detail, specifically the bend, i dont know where it goes.

[scraptopower]

Put the bend against the side of the can and wrap the longer end of the wire around the can. Twist the two bits together to secure.

[wiinick]

So sewing thread is a go.

[scraptopower]

Yeah, just oil it before you use it though!

[wiinick]

Hey i found fishing line, nvm but each comment on this tut is one less question someone has to ask you, they just have to read my comments. So in a way im making your life easier. A thank you isn't needed.

[DominicEdmundoVelazquez]

wowwww

[wiinick]

Just want to be safe here, but can i use sewing thread instead of fishing line.

[SURAJ1992]

HOW DID U INSERT THAT bent paper clip inside the rolled wire wool??

And do we need anything to keep this wire wool from unfurling and rubbing the can??

[scraptopower]

Just push it in ?

[SURAJ1992]

So push it in and the roll will keep from unwrapping??

[ilpug]

probably. steel wool tangles up with itself pretty easily.

[wiinick]

Ok so my steel wool is in there, there are some gaps in it, for air passing i guess you can say its a big gap, it looks tighter than what ur picture looks like, but either way it falls on its own with relative ease. I put the paperclip in and it stays, so i'd like to ask is the steel wool in right, like noticeable gaps are ok, answer that and ill get out of your hair for a while(until i need to ask yet another question, bear with me).

Oh and how power full is this thing, could you send me a link to your newer on thats more complicated, my idea is to make this first to figure out how it works so i can make a more complicated one and understand it.

[scraptopower]

Wiggle the displacer around a bit more just to be sure it falls freely. There's just a small gap around the displacer, maybe 1-4 mm. It won't be the same all around the displacer though, some parts will be nearly touching some parts will have a gap.

Small Stirling engines really don't have much power at all, I couldn't give you a measurement though!

[D00M99]

I have been wondering about what wire to use for projects like these. Where do you get them and which ones work best?(in terms of support and strength)

[aashilrv]

does it have to be zig zag?

[engjunpil]

@redjant44: maybe if you use magnifying glass and mirror as reflector to convey the heat of the sun and magnify it using lens or magnifying glass.

[wiinick]

how snug

[scraptopower]

It should fall under it's own weight. If it doesn't, squeeze it against the side of the can until it's small enough to fall.

[wiinick]

wow man, fast response time

[wiinick]

good good, if i put it under a candle will it rise

[scraptopower]

No.

[wiinick]

Now why is that, edjumacate me if you will.

[scraptopower]

Well, I'm assuming you were talking about the displacer piston, which is made of Steel wire wool. It's not air tight, so it won't rise.

[wiinick]

ok, but how does this displacer help the engine move, i know the basics but the only thing i dont get is how the displacer(not airtight, does it have to be?) helps the engine move. To better refrase this question, what is the purpose of the displacer and to make a real displacer does it have to be airtight.

[scraptopower]

The displacer doesn't make the engine move in any way. It's purpose is to move (displace [r]) the air between the top and bottom of the can where it's heated and cooled. When the displacer is at the top of the can, most of the air is displaced to the bottom of the can where it's heated, causing it to expand, this pushes on the balloon making the cranks turn. As they turn, the displacer moves to the bottom of the can, displacing the air to the top of the can where it is cooled down, returning the balloon to it's original position. This keeps on going :)

[wiinick]

Wow, this is the only time i have asked a question online and someone actually responded with useful fully detailed information. Thanks that made my day.

[wiinick]

Help me im begging you

[wiinick]

A meter, That pictur doesnt show a meter

[scraptopower]

The picture shows marking the bearing supports 15 cm from the end. A picture showing a meter of wire wouldn't be very useful .

[wiinick]

bwaaaaaa

[wiinick]

This picture is hard to tell is there supposed to be a gap

[perfo]

Excellent ible. I think projects like this are what this site is all about. You never know, a kid building this due to your ible could produce the next scientist that has a major breakthrough in later life.
Simple, easy to build and works.
Thanks.

[delete]

Wonderful instructable, and many thanks for introducing me to the Stirling Engine!

One question: Are the Diaphragm connecting rods intentionally curved outward from the diaphragm in the very first image, or could/should they be straight from a front view?

Alternately, would a 2d diagram be at all possible?

[ShemySheza]

Your a genius..................

[redjant44]

REDJANT 44

IS IT POSSIBLE TO FOCUS THE SUN'S RAYS AS A SOURCE OF HEAT TO POWER THIS? USING SYSTEMS OF MIRRORS OF COURSE.

SIMPLE BUT ELEGANT. MORE POWER TO YOU.

[Matrix-technician]

LOL, yes it is possible. There are even stirling engines that can run off the heat of you hand. Try googleing stirling engines.

[ecoego]

you might think about using something that gets hot from the suns rays first and see how well that works. A larger more durable version of the Sterling Engine would be of better interest. The pop cans are fun to get your blood running, but what can it hurt to go a little farther?
I would start gathering ideas of what to use to create the larger version. For instance the 'can' = use a 55 gallon drum... and so on

[perfo]

Something like this doesn't scale up very easily. Any energy lost in the distortion of the can due to pressure build up is quite small in the above example but would become a big problem with a barrel. The thermal masses and conductance involved with the barrel would also be a problem. The good thing is if the clearance of the displacer to the outer shell is kept the same then in % terms you will move a lot more air with it when scaled up to barrel size. I think a scaled up version would probably need two separate elements i.e. a hot end and a cold end, optimised for their respective jobs and insulated from each other with air pipes running between the two. A regenerator would also be helpful. The practicalities of scaling and of reliability of the various elements have been what have stopped a brilliant idea from being a main stream source of motive power. However there is a company called WhisperGen that claim to have got it sorted and actually use the Stirling engine in domestic CHP units.

[ecoego]

Any thing is possible. You will have alot of work to do or money to get that running properly.

check this link out:
http://www.electro-tech-online.com/electronic-projects-design-ideas-reviews/107205-solar-tracker-problem.html

[kutil]

:D WTF can be this used for :D its awesome !

[komodoboyx5]

1. you could take it on a camp-out and use it to rotisserie cook your foods. the fire provided by a campfire

2. hook up enough to make a powerful car, boat, something worthy of transporting people.

3. make a fan, as somebody posted in another instructable

4. Power a home utility with these.

5. Win science fair.

6. Impress MacGuyver.

7. Perfect it.

8.Rework it to make it run on sun/engine heat/anything else

[kutil]

I have girl and real life . MacGyver . I am your friend have a nice day .

[chaitanyak]

awesome! will make this soon!

[conceiveplus]

This is really nice i stumbled upon this, my lil nephew has a technical bent of mind and he will surely love to give his hand on this, thanks.

Alex

[gafisher]

Very good! Truly a Stirling, er sterling project!

Those concerned about Coke vs. Pepsi might want to consider other beverages. Canned V8 juice, for example ...

[splazem]

No, Coca Cola trumps all.

[scraptopower]

Coke IS better than Pepsi, but Pepsi comes in Steel cans which are strong, coke comes in lowly alu cans :)

[TANZMEISTER]

The beverage aside, lowly 3004 series rolled aluminum? Are you kidding, that's the best all purpose shim I've ever found.

[splazem]

We (Coke Lovers) even have the author agree with us, so there. And yes, their cans are stronger, which is usually better for projects, but when looking at taste, Coke wins.

[lilBoomBOom]

Very good concept!!

Just curious how fast roughly does it operate?? have you ever thought of doing a multi-cylinder sterling engine??

[scraptopower]

It runs about 180 rpm. It seems faster though because it's noisy and wobbles a lot :)

[spenfisher12]

would a long shank fishing hook work instead of the paper clip

[scraptopower]

Yes, should do. It just has to hold onto the steel wire wool.

[annamalmberg2]

Just love it and I certainly must try it

[scraptopower]

Thanks for all the great comments! I didn't expect to start a "war" by using a pepsi can, it was donated generously! I prefer tango :D

[splazem]

Wow. Ingenious. Hate to be like this, but you say coke can, when you show a pepsi can. I wouldn't care, but we all know Coca Cola is sooooooo much better than Pepsi. We know that, right?

[Cephus]

It's the real thing. Coke adds life.... all that good stuff from ages ago. I never felt free enough to join the Pepsi Generation.

[splazem]

I agree.

[MaXoR]

And now for the crusher..... sadly they are both owned by the same parent company, and have been for years. So even though one may prefer the taste of one to another, the profits go to the same place (oops, that was a little off topic)

Coke is also loaded with sugar, and far more acidic than pepsi. I personally think pepsi tastes like water, but coke just makes my teeth feel gritty. I'm a Dr. Pepper fan, and always will be.

If you're going to put something that horrible (pop in general) into your body, you might as well go for the best flavored. (lol, my opinion only. I can only imagine what comments this will entice out of others)

As for this ible.... kudos! Simple, effective, and readily available parts... top ible in my books!

[digus]

Coke - It's just not the same without the cocaine...:(
Ah, the "good ol' days"...

[featheredfrog]

Coke and Pepsi? Different companys entirely.

[MaXoR]

I retract my previous statement of them being the same parent company. I had read it online a few years back, and I guess it was a hoax. I know the adage of not believing everything you read, however I had referenced more than 5 websites with the same "press release".

I still stand by my opinion stated in the two preceding paragraphs. Thanks for the push to re-research the point about them being under the same parent company.

[splazem]

But if you had to pick, Coke or Pepsi, it would be...?

[MaXoR]

lol, neither, if there is no Dr. Pepper, I go straight for the coffee, or a simple glass of water. Not going to put an acid in my mouth unless it's going to please my taste buds, and as I stated above, neither pepsi, nor coke(lol...let the jokes roll) do it for me?!

[splazem]

Coke > Dr. Pepper. End of story.

[featheredfrog]

I'd prefer Diet Coke -- Pepsi products taste to me the way Pine-Sol smells

[splazem]

Oh no. Diet coke is NOT Coca Cola. It's like fat free ice-cream. It loses all of the good taste that REAL Coke has. But, at least you picked Diet Coke and not Pepsi Max.

[the tech head]

pepsi all the way

[splazem]

If you can't say something nice, don't post a comment. Coke IS better. You don't get an opinion in this matter. Sorry. That's life.

[the tech head]

i like Pepsi personally its the best

[splazem]

Right now, I want you to go to the store. Buy a can of coke. Drink it. Enjoy. Then tell me which is better, Pepsi or Coke.

[the tech head]

ive actually tried them side by side i liked pepsi is better in MY opinion BUT! i will choose coke over other brands if no pepsi

[splazem]

Next time, do yourself a favor and choose Coke, even if there is Pepsi there.

[digus]

"I was reading a book
Or maybe it was a magazine
Suggestions on where to place faith
Suggestions on what to believe
But I read somewhere
That you've got to beware
You can't believe anything you read"

--Jack Johnson

[burnerjack01]

Considering the medium, doesn't that make this an illogical argument?

[digus]

hehe - not sure if you're replying to me or not - just thought it was a good and fitting quote. If you were replying to me, I'm pretty sure my logic is sound, in this context...

But I read somewhere
That you've got to beware
You can't believe anything you read

I'm guessing you accidentally replied to my post though, instead of the one you deemed illogical...? Curious now tho... ;^)

Cheers!

[splazem]

That's hilarious!

[sommmen]

luve it! only doesn't look so fancy..

[chrisnotap]

I didn't know what to expect when It said "coke can engine" > So amazing. My hat goes off to you. Great work, so incredibly simple.

[johniram]

Amazing! Great work.

[dombeef]

You are awesome!

[ac1D]

Very nice!
I watched the video, and I can't resist! I need to make one :)

[RedneckEngineer]

I love it! Looks like it wants to take off and chase you down the hallway! Now if you can take this model and improve it with other parts you may increase the output and make it even better. Keep it simple and you hit it on the head!

[rimar2000]

Very good work!

[MonkeyBoy3217]

Holy crap that thing is like a monster... GREAT instructable. Im making a sterling engine, I hope mine is as good as yours!

[ShemySheza]

thanx alot.the first one was a bit complicated