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Wagon Wheel Stirling Engine

Nigel Taylor

The large flywheel looks like a wagon wheel and so the name. The flywheel is horizontal with the framework of the engine around it.

This first image shows my roughed out sketch of the engine from above.

This next image shows the side view. A slice through the displacer is also shown.

The idea was to make a flywheel 240mm in diameter, not a hope of me turning this on my Hobbymat lathe and so the decision was made to make it from wood.

To get the flywheel as accurate as possible I made up a jig and this is what you see to the left, at this stage with the centre part still there after fretsawing the circle.

A 6mm coach bolt goes through the centre.

This is the jig, sadly no more photographs were taken until I had completed the flywheel and so I will describe the process.

I used 1.5mm thick walnut that was 15mm wide and bent this around to fit in the jig. I cut the ends so as to get a clean single piece around the inner of the jig.

I then added another layer of 1.5mm wood with the joint offset from the first. The layers were glued together with PVA glue.

Once I had enough layers I then added the spokes and glued these to the rim and a centre disc. Once all were in place I glued the disc on the centre and added a thin piece of wood to the inner of the rim to hold the spokes in place.

Then leave overnight to set.

This shows the varnished flywheel.

As you can see looks just like a wagon wheel.

I drilled 32 blind holes around the rim of the flywheel and into these placed small magnets (taken from some Geomags) - take care to alternate the orientation of magnets north to south.

The intention is that this will drive a smaller wheel with magnets at the same spacing and the centre forming a fan. Hopefully the result will be that I can cool the cold side of the displacer.

The hot end of the displacer cylinder machined from solid brass. A tad extravagant, but does give a great result.

There is a bit of a locating edge machined into the cylinder.

The frame was made from 1/4 inch wood. The end panels were made from homemade ply. Note that there are two bulkheads at each end.

At this point I still need to build some more stiffness into the frame and to add the plates that will hold the bearings for the flywheel.

The wheel laying in the frame in roughly the correct position.

I now need to make some bearings and the main crankshaft. Part 2, Part 3, Part 4, Part 5, Part 6

If you have made a similar engine and would like to share your experience we would love to hear from you - ed.