Ceramic Stirling engine.3

 Succesful  ceramic engine.

With respect the starter SFA stirling engine that I showed you two weeks ago. We substitute for clay the flywheel, the burner, the power cylinder and one of the metal support of the crankshaft.  However the key for the achievement in this time was to restrict the weight of the pieces. So the experiment was cheap and easy. The clay was fired with sawdust in a typical homemade furnace. For this reason the pieces are of dark color.

 A view of the machine.

Items in clay.

-Now there is a comparative between the metal original parts and the equivalents in clay.

The burner.

 With a ballpen like mold we made three columms of 6 cm of lenght.

 The same bottom of a can is useful for to do a similar in clay.

Upper view
Bottom view.
Ceramic burner ended.

We joined the pieces with some of epoxy.

 The power cylinder.

Ceramic power cylinder
 For the power cylinder a candle was the most appropiated object for to cast.
Original power cylinder in PVC

 The Flywheel.

 -The ceramic flywheel is slightly more short .

 A support for the crankshaft.

 The result is very similar in question of weight.

 and the result:

 surprisingly more fast and noiseless than the original!!!


 The same video in Youtube here

 -Now we are more close of to get our aim, so the displacer and respective cylinder are the next...

Health and safety.

One thing we have in mind when we work with ceramic material is to preserve our health. It's normal that working with ceramic items produce pollution in the air (dust), for this reason is a good idea work outside or room with a good ventilation.

Here is a link about silicosis in wikipedia.

Ideas for to work with glass.

One idea for to make a small cylinder very cheap could be using a wine bottle and cut it with heat and water as I showed you before. The result  is a small cylinder of 25mm of diam and 40mm with a usual green bottle.

If you have microwave oven in your house, you should know that this is a powerful tool because you can melt glass with it. All that you need for it is to build a small melting pot.

See the next links:




fusing metal:


Third try.

In this chance we experiment and change the next items:

 A displacer made with Pómez stone, (vulcanic) very light,
and with a rod made of clay.

A displacer cylinder made with clay and with a size equal than the original model.

The top of the same cylinder made with clay.

The power piston made with the classic rubber and with a basis of epoxy and cement, the rod is from clay too.

 The machine ended, as you can see the result is a machine very light.

A video whereby we can see the failure in this try.


 The bad conductivity of the clay avoid to run our machine. In this try only the crankshaft and the con-rod are from iron, the rest is of clay, rubber and epoxy.

Two  experiments on reflection .
After the last try of a ceramic engine, I'm wondering if the  cylinder of clay acts like a shield of heat. But I heat another cylinder of clay with a candle during 30 seconds. The result was the walls are hot, inside and outside, furthermore I heat a glass cylinder from a bottle cutted and the result was equal. So I feel that if a glass cylinder is good for stirling engines, the clay cylinder should be good too.

The second experiment I did, it was with pumita stone, I dive a piece of this rock in water during a minute. The result was the stone before to dive was 41 grms and after 54 grms. So we have an increase of mass of 30%!!!. I think though pumita could be good due to it big surface, at the same time this item create a big dead space in the engine and unable to run the machine properly.

Fourth try.

The change in this time was to change the configuration of the displacer, with a good result. We cover all the surface of the displacer ( pumita stone) with a mixture of cement and epoxy. The result was a piece some light and solid.

The machine finished again with a powerful fire based in alcohol and paper creased; the cooling is small items of ice.

In the video you can watch that the power of the small balloon has increased, so that we can confirm only pumita stone is a bad material, nevertheless covering its surface with cement and epoxy could be great like a light a effective displacer.


An instance of displacer cylinder.
The machine during the experiment reach high temperatures for to melt the ice and all the structure was very hot at the end of the fire. However remain one important point the displacer cylinder. I feel that clay is really bad transmiting the heat and for this reason we could change the clay for a glass cylinder cutted from any bottle. I think the result could be improved a lot, furthermore there are some engines working with glass displacer cylinders, (see my another pages of ceramic engines). By the way, to cut a bottle with a string wet in alcohol is not too easy as you could think, it have its technique and some of practice is needed for to get good cuts. Continuing on the path to spend little money, we can avoid to purchase the drill for glass if we put the power cylinder on the top of the displacer cylinder and not in one side. See the next image;

One possible idea is to get the previous burner that I made in clay and join it with the bottom of a glass displacer cylinder and the top of this cylinder build it with clay and the power cylinder and the flywheel with clay too.Only the rods and the crankshaft could be of iron and the power piston made it with a rubber diaphragm like the original SFA stirling engine.  That is my next goal but for the moment I can't continue experimenting because I have been five years jobless in Spain and now I have found work in Germany and in the next days I'll move to that country for to do my life, when I can, I'll continue experimenting this sort of engine. I  hope that if you are thinking to build a domestic ceramic engine this information have been useful for you. Like the people say in Gemany,  
Bis bald!