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The E Z Stirling has been very popular and thousands of free plans have been sent out.
I hope this one will be popular too.
This version will run when placed on a cup of hot water and I have tried to use materials that are easily available.
Builders in Europe will recognise the supermarket bag in the opening video shots and see where the main materials came from.
The engine will also run on ice.
In the video below it is running on frozen peas.
Building tips
The fit of the needle in the pencil top is important as this should be very free, the displacer needs to fall under it's own weight, whilst giving an airtight seal.
If you are using the same Bic pencil as me, looking in the inside of the tip after it has been cut off you will see 3 little protrusions that were to grip the pencil lead. It is helpful if these are opened out so they do not touch the needle. This can be done by pushing in a pointed tool like the end of a pair of compasses.
Fault finding
If your engine does not run check the following.
Make sure everything is free. If you give the flywheel a spin it should continue to rotate for about 5 seconds with the displacer and diaphragm connected.
Place the engine on a cup of boiling water. The diaphragm should immediately rise. If it does not move there is an air leak somewhere. Moving the displacer up and down by hand should make the diaphragm rise and fall.
The seal between the tin lids and drinks bottle sleeve is very tight so there should be no problem with leaks there.
Check the rubber band is sealing the diaphragm properly.
Assuming the glued joints to the tin are sound another possible cause is where the needle passes through the pencil top. Maybe your needle size is too small. The needle needs to be a close fit but still be able to allow the displacer to drop under it's own weight. A drop of WD40 or similar will help if it sticks.
The displacer should not touch the top or bottom lid. Adjust the length of thread to achieve this.
Make sure the cranks are set at 90 deg. When the displacer is at the bottom, the crankpin on the flywheel has to be at 3 or 9-0-clock.
The set up and fault finding information for the E Z Stirling Engine also applies to this engine so if you cannot get your to run please see the tips and video. shown on that page.
Alternative Materials
If you cannot get the travel sweets an alternative tin of near similar size can be used. The original is about 98mm diameter.
If you have a different diameter tin then the 2 lt drinks bottle is not going to fit like mine did.
One solution would be to roll up a cardboard cylinder and use that. You would loose the visual appeal of the displacer slowly rising up and down though.
If you choose this route I would suggest making the tube from two layers of card one stuck over the other with the joints in different places. If it were made in one piece and simply rolled and the ends glued together there would be an air leak where the overlap was.
The tube must be airtight or the engine will not run. Silicone sealer could be used to seal a cardboard tube if the fit was poor.
The displacer diameter will need to be changed if a different diameter tin is used. Make the displacer diameter about 8mm smaller than the inside of the tin lid.
On the original engine there is a gap of 27mm between the two lids and the displacer is 13mm thick. If for example your polystyrene displacer is slightly thicker, say 15mm, then the gap between the lids should be changed to 29mm so the free space remains the same.
I also made a mini version with 50mm dia tin lids.The engine runs well on a tea light but would not run on hot water. Being small the diaphram does not have much surface area. In place of the plastic botte to connect the lids i used a rolled up carboard tube as suggested fot the engine above. For the displacer florists foam was used.
