Fully 3D printed LTD Stirling Engine (ProjectsToPrint)

This is a fully 3D Printed Stirling Engine made by New Zealand ProjectsToPrint (now defunct). It only requires a printer, printer materials and a few basic home tools and materials to make. It is powered by hot and cold water. This does not use any metal parts and it does not require a machine shop to make precision fitting parts. The traditional precision piston and cylinder is replaced by a printed diaphragm. All bearings are printed, the pivot pins are FDM filament. This engine was first run on the 25th of September 2014.

Addendum: Try to minimize these things for good operation... No leaks: Your can have only a tiny amount of air leaking around the shaft that moves the displacer up and down. If too much air leaks here, or anywhere else, your engine will not run.

Good heating and cooling exchange: Your must also have good heat absorption on the hot side and heat rejection on the cold side.

Low friction: Friction comes from two places: the working gas (in this case, air friction) flowing inside the engine, and the external friction of the mechanism bearings and pivots.

Proper contraction and expansion ratio: The gas has to expand and push the piston up and then contract and pull the piston down. It’s fairly easy to see how you might get this wrong by setting up a crankshaft throw position that has either too much or not enough travel. You should get quite close to a good ratio if you are running your engine on ice and hot water.

Addendum2: The original was printed in ABS and pressure areas sealed by application of acetone. (can apply by using cotton swab). The piston and displacer mechanisms are approximately 100 degrees out of sync, with the displacer being ahead of the piston. The engine can reach a peak speed of about 75 revolutions per minute.

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