machines which I have made, am making, or intend to make, and some other stuff. If you find this site interesting, please leave a comment.

KoffieKop Engine Working!

I assembled the engine today.  The flywheel was required to be balanced, but I decided to give the engine a run in its unbalanced state, and was quite amazed to see it start up, hesitatingly at first, but then got into its stride, and ran for 13 minutes.

Quite excited at this point, I spent some time balancing the system.  That required the base to be removed, then multiple holes, 7 in all, drilled in the flywheel, to balance the mechanical components.

Then another run.   14 minutes.  Then another, 19 minutes.  Then the best run at 21 minutes.  Very exciting.

So I took it home, and showed SWMBO.   Hmmm.   But what does it do???  She asks.

It just goes…..   It is like an architectural folly.   Just interesting in its own right.   OK?

So this is what you have been spending your spare time on for the last 2 weeks?   Yes.

A bit of a credibility gap here.

The engine, sitting on a cup of hot water, running at about 100rpm.

The engine, sitting on a cup of hot water, running at about 100rpm.


Best run…. 21 minutes.

Koffiekop Engine

I have been busy for the past week or so making a Stirling cycle engine.  It is the Coffee Cup engine designed by Jan Ridders.  It is powered by the heat from a coffee cup of hot fluid.  Or an ice cube sitting on the top plate!


Page one of five of Jan Ridders excellent plans.

Page one of five of Jan Ridders’ excellent plans.

Most of the components of the coffee cup engine.

Most of the components of the coffee cup engine.


100mm flywheel.


Possible alternative flywheel, roughed out, I will see how it appears with a bit more finishing. Looks interesting?


An experiment with engine turning on an aluminium surface, using a “Brownells Engine Turning Kit”, kindly loaned to me by Stuart.   The pattern is made with the spring loaded wire brush seen in the picture. I used this on the upper plate of the displacement cylinder.

Lots of tiny fiddly bits.

Lots of tiny fiddly bits.

The piston is made from graphite.  An interesting material to turn.  Surprisingly tough, accepting a 3mm internal thread.  And presumably self lubricating. Machining it produces black, pervasive dust.  SWMBO is not impressed, since my CNC lathe sits in our living room.   I might get marching orders for the lathe as a result of this one.

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