Stirling Engines My first Stirling engine build

In spite of my video camera running out of battery during filming, I managed to get the first (and only) moments of my first Stirling engine running.

Tis a funny kind of beast running so slowly and deliberately.

I officially like Stirling engines. Mine looked like this...

It ran for a total of about a minute before the displacer fell to bits. It was sealed airtight, and as it got hot it just popped. It turns out there isnt really any need to make it air tight.

I think.

My displacer started life as a soft drink can.

I marked out a straight line to cut it down to size.

I took a guess as to what size it should be.

I scratched a series of arcs with a bent piece of sharp wire, each at different points, to find the centre, then punctured it with a drawing pin. 

I marked out another can, but this time much shorter.

Then squashed the big one over the little one after turning the little one upside down.

This gave me a sealed can again.

I glued it with super glue.

The gluing was what killed my brand new Stirling  engine after only 60 seconds. As the heat increased, so did the pressure inside the sealed displacer, and eventually it popped open.

I poked a straight length of fencing wire through both holes, then bent and super glued one end to stop it slipping through.

My wire originally had a slight loop at the other end, but I had to cut it off to remake the thing after I glued myself to it.

Dont do that.

And if you want to be really scared, use super glue, then adjust the dials and buttons on your new camera with the same fingers.

Anyway, the main thing is stick some wire through the displacer.

Next I took a tin can and smacked a hole in it with my familys trusty meat mallet.

This meat mallet used to be my mothers (it probably still is), and was used as the household hammer for as long as I can remember.

Here we see the entire family history of hammering.

Actually thats half the family history of hammering. The other half is of course, on the other side.







So then, I took the length of wire sticking out of the displacer (soft drink can thing), and threaded it through the bottom of the tin can.











Like this.

Its a bit difficult to see, but thats the soft drink can displacer thinggy under the tin can.









Next, I took another tin can and drilled a big hole in the side.










And sanded down a small plastic bottle so that its contour matched the tin cans.










Then cut a really big hole in the side of the small plastic bottle.

Something like a pill bottle would work.

All this, so I could glue the small plastic bottle on the side of the tin can with a big hole in the side. 

Next, I stretched a balloon over the entire little plastic bottle, and pulled the slack so that it was tight everywhere but the top.

I also glued a length of wire to the centre of the slack bit.

This, believe it or not, is something called a "power piston".

Ill explain what all this stuff does later.


Next I bent a crank shaft, and some mounting points for the wires coming from the displacer (through the bottom of the tin can), and the wire glued to the balloon (power piston)

The crankshaft has one offset bit (offset by around 8mm) to attach the displacers wire, and another to attach the power piston wire to.

The two offset, (bent out) bits, are at 90 degrees to each other.

So from the left...

straight, then down, then straight, then back up to the original.

That makes the first cranky bit.

Then continuing straight, then back, then straight, then forward back to the original plane.

That makes the next cranky bit.

If you look at the crankshaft end on, if one crank was at 12 oclock, the other would be at 3 oclock (or 9)

I found this almost impossible to get on camera (or to explain), but it looks like this.

Its probably best seen on the video.

The crankshaft is lightly held in place with two inverted U shaped bits of wire taped to the sides. (just visible near the top, left rim of the device)

I stuck a cardboard disk about the size of a CD onto the end of the shaft to act as a flywheel, and then added nuts and bolts with blu-tac until the thing was balanced.

To get them in the right spot, I put the disk in a random place, and if it rolled back to a different position, Id stick on a weight so it wouldnt.

I should have been able to do this with just one weight of the correct size, but for some reason it was beyond me.

So...

• The displacer is the soft drink can thing inside the bottom can. 
• The bottom can is sealed ([buy - EDIT  - note from the future-  Who makes errors like this?] by the top tin can) except for the small hole in its top that has the displacers wire poking through.
• The displacer travels up and down inside the bottom tin can with a total travel of around 1cm.
• The displacer gets very close to the top and bottom of its tin can container, but never actually touches.
• The displacers wire is connected to the crankshaft (between pink beads)
• The power piston (pink balloon) is floopy, and connects to the crankshaft 90 degrees offset from the displacers crank.
• The top tin can is there to hold up all the other kit, and as the top seal for the chamber holding the displacer (soft drink can thing)
• When the air inside the bottom tin can heats up it expands, forcing the power piston up. This turns the crank and gives the device its power.
• As the device rotates, and the displacer moves down, forcing the air up and away from the heat, so it cools and contracts. 
• When it contracts, the power piston is sucked down.

Thats pretty much it. Repeat as desired, or until something breaks. 

Some light oil can be added to any surfaces that have friction. (where the displacer wire moves up and down into the bottom tin is a high friction area)

==============>>> IMPORTANT!!! Note from the future - It turns out you probably shouldnt add oil to the point where the wire slides through the can. Theres a chance of explosion as the oil is heated to a gas. <<<================

120 things in 20 years - I made a Stirling engine!

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Winner The great MPPT solar charge controller competition

So I asked the invention engine what kind of competition I should hold to give away that first solar charge controller I bought, and it said I should ask everyone else.

Helpful.

It said I should get a load of people to submit their ideas.

I asked it why people should spend their precious time helping me out with their ideas.

It said I should provide some kind of incentive.

Like a competition.

So the first ever 120 Things in 20 years competition is as follows...



Whoever can come up with the best idea for a competition wins.

The prize is that solar controller I had so much trouble with because it didnt match my solar panels too high voltage.

There is only one rule*, and that is the winner wont be anyone who enters by simply adding another layer of competition to the competition to see what the competition should be.

I already thought of that one, and Ive decided I probably wont give the prize to me, although I am currently in the lead so I may change my mind.



Mrs 120 Things and I will judge the winner at our own discretion, in our own time, whenever we feel like it, if we feel like it, and reserve all rights to do whatever we want without reservation or regard for others.



120 Things in 20 years thinks the invention engine may have just gained consciousness, or at least the beginnings of a consciousness-free sense of humour.



click the comments thingy to enter or offer derisive laughter

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Thinking Paradise

Paradise is usually documented by pristine beaches that have an opalescent, turquoise quality.

Its just polarised light.

Buy some polarised sunglasses and look at your local beach.

Wear them all the time, and theres no need to fly anywhere!

This tip brought to you in the interest of staying at home. Its got everything you need!

Except broad horizons.

No matter where you are, the horizons are not broad enough.

Travel if you can.

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Winner The first 120 things in 20 years competition

So a while ago, I bought a MPPT solar charge controller.

It turns out the nice ebay based company I bought it from was a fraud, and sold me a product that wouldnt work with my solar panel in spite of my having asked them and then double checking. My solar panel had too high a voltage, but the listing said it would be fine.

Anyway...

The result was that I was sent a product that didnt work as advertised.

Eventually ebay made them give me my money back. The company insisted I return their product at my expense.

I posted it to their registered address, but the post office in China said there was nobody by that name at that address.

So China Post returned it to sender.

Me.

All this is old news to anyone who follows this blog, but this is the new bit.

I thought Id give it away because its of no use to me, and might be exactly what someone else wanted. But who to give it to?

I thought Id hold a competition, and give it to the winner, but I cant think of a decent theme.

The current plan for the first ever 120 things in 20 years competition is to run it through the invention engine and see what it thinks.

so... stay tuned I guess. Its late, and Im going to bed.

Tomorrow, the competition begins!

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Stirling engines Adjustable Stirling engine crankshaft

Ive been busy making the tips of my fingers raw.

Wire seems to enjoy hurting people.

But I love the stuff.

My time learning how to make screw in eyelets for my hand made fishing lures was well spent. Every new skill I pick up seems to inform my next project. Working with wire is a really worthwhile thing to learn.

• This post appears to be in bullet point style.

One thing I dont really understand is the relationship between the size of the cams on the crankshaft and the performance of my little tin can Stirling engines. With this lack in mind, I thought Id build a completely adjustable crank shaft.

It looks like this.

With it, it should be easy to try a stack of different configurations to see what they do.

The cams (bits that are offset from the main shaft) should offer different combinations of engine torque, and speed when they are adjusted to different heights.




I think.

Ideally I need an adjustable chamber for the displacer as well. Ill have to feed that idea through the invention engine at some stage because I have no idea on that one.

All the brass fittings come from the brass bits in strip electrical connectors.

Once the screws are undone as far as they can go, all the brass bits fall out with tap and a jiggle.

Lots of taps and jiggles actually, but they all come out in the end.





In my adjustable cam, the brass tubes that accommodate the cams have had an extra hole drilled through. Brass is very easy to drill, and a pleasure to work with. I dont think Ive ever done anything with brass before.

I officially like brass.

• Bullet points

Also, many other people have used these as the adjustable bits on Stirling engines, and my only contribution to the science is to take their use to absurd levels.



120 Things in 20 years - No time to post because Im too busy learning stuff about Stirling engines.












All the brass bits are taken from a strip of electrical connectors.

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Stirling engines My first Stirling engine

Sometimes I struggle a bit with certain aspects of construction, but in this case I wasnt even certain of what I was attempting to construct.

Most of the problems trend around a certain frantic waste of pace and failure to pay attention to detail.

This time was no different.

A Stirling engines basic list of components include a cylinder, a displacer, and a crankshaft.

They also include a hot bit, and a cold bit.

Its the difference between the hot bit and the cold bit that makes a Stirling engine an engine.

Theres also another really important bit, called the power piston. The power piston is connected to the same crank shaft, but on another crank. This crank is offset from the displacers crank by 90 degrees.

Im not really sure how it does what it does, but this is my first attempt at making a Stirling engine.

The power piston is the bit thats missing, because I didnt get that far.


Some of the other missing bits include the rest of the components that make up a Stirling engine.



120 Things in 20 years - On a scale of one to ten, where one is a total fail, and ten is a total success, I wouldnt bother rating my first attempt at making a Stirling engine.

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