RIDDERS “BOBBER” HEAT ENGINE
by John
As you can see from the picture, the Ridders “bobber” is quite a pretty engine.
If it works perfectly it develops just enough power to revolve, but not enough to do any work or to overcome any perceptible internal friction.
Unfortunately, my Ridders does not even turn over with the heat applied. It revolves freely by hand, so I do not see where the problem is. In any case, now that I know how powerless these machines are, I have lost interest in spending more time on it, and I am returning to paint and finish the beam engine.
The pictures are for interest only.
(ps. Note made April 2017. About a year after I originally posted this, I returned to the Bobber. I made a new piston from graphite, replaced the 3 steel balls with ceramic balls and retried it. It still did not work. Then I tried varying the number of ceramic balls. With 2 balls, it ran perfectly! Smooth and fast. There is a video of the feat in a later post.)
Almost fully machined Ridder “bobber” heat engine.
With heat applied.
Unfortunately it does not work.
johnsmachines 
Golly John, if you are having trouble getting it to run, I will be in strife. So far I am messing with getting the piston and rod concentric with the bore. Obviously not holding my mouth right as no where near it first try. Although trying Jan Ridders test of thumb over the end the piston hangs dropping when thumb removed. Just ain’t centered. Still, it’s keeping me amused for now.
John B
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Stirling engine, Stirling cycle. Bring back bad memories of thermodynamics from my BE!
Looks a very interesting, simple machine, despite the power generated being only enough to overcome internal friction. It does have another purpose however: it may not be able to do physical work, but it is a practical demonstration of the application of the Stirling cycle, which most students would only see in theory, in textbooks.
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Hmmm…. it still does not appeal. Maybe if it worked I would feel differently.
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John, the web address for company I got the bearings from http://www.bocabearings.com/
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