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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Handmade fishing lures Mold making Prototyping plastic

I just discovered my new favourite substance.

Its even better than PVC.

Maybe it is PVC.

I dont know.

I was in my local electronics store checking switches, and was sold some of this stuff.

Its plastic that you can warm up and shape.

You need to get it to around 65 degrees c before it melts into itself.

Once hot, you can shape it into anything you can think of.

Pictured here is a bit I squeezed.

It retains fine detail like fingerprints, and when dry, it sets white like the beads again.

It sets to a strong plastic with a little flex, a lot like a soft drink (soda) bottle cap.




My first use was to make a very specific battery pack that didnt exist as far as I could tell.  Its great to work with, and totally recyclable. You just drop it back into hot water, and it re-melts.

I would guess you have around a minute to work with where you can press two bits together and they form one. And perhaps another minute where you can still shape it, but pressing two bits together wouldnt quite become one.

If you need more time to work it, you just put whatever youve half made back into hot water and it softens again.

Very cool stuff that I think Im going to need to buy in bulk.



120 Things in 20 years is excited about making handmade fishing lures, and just general prototyping  In reality, I have no idea what Ill do with it, but its exciting just knowing about it. Im easily excited.

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Electronics Aquaponics Demand feeder fish lever build

I spent some time in an electronics store testing long buttoned momentary switches.

They all seem to work when you tilt the button to the side as well as when you press the button normally. Perhaps they are designed to work that way after all.

Thanks button maker.

I had a bit of a breakthrough with the entire lever, and not just the switch part. I found this fishing float had a white plastic bit that almost fit over the momentary switchs button.

Thats the switch lower right.

The white plastic thing was hollow, but needed a slight enlargement with a hand held drill.

The button went in with a snug fit, and the white thing was really their just to give me some surface area glue onto.

The new lever incorporated a second fishing float as the stem, and as a nice bulb for the fish to hit.

The float stem has a bit of flex to it, so it should be forgiving if a fish hits it hard.

It looked lie this when built.

I glued it in place with super glue, and held it while it dried with what to me looks like a naked chicken with a fist for a head.

So now my device looks like this.

It also works.

I turned it on, and while I was putting a cover over the fish tank, the bigger of my two fish hit the lever and got a feed.

I did have the camera running, but the video was too dark to post, but the switch and lever worked perfectly.

I count this as a success!











120 Things in 20 years suggests you never try to take your electronic aquaponics demand feeder on a plane with you, unless you feel like explaining it for a few hours.

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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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Electronics Breadboard multimeter adapter

For some time now Ive been looking for a convenient way to probe around my breadboard with my multimeter. It can be a little tricky, because the probes are too thick to get into the little holes on the breadboard.


I had a bit of an idea today.

I came up with this...

Its a stereo headphone jack with a long length of header pin (sturdy wire used as a plug) soldered to the legs.

I added some insulation in the form of heatshrink, and...

TaDah!

The 120 Things in 20 years multimeter breadboard adapter.

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