According to The Guinness Book of World Records, the world’s smallest steam engine is the “Thumbnail Steam Engine” built by Iqbal Ahmed. Mr. Ahmed is one of our featured craftsmen, and a Lifetime Achievement Award winner. However, this oscillating steam engine built by Jerry Kieffer is even smaller, lighter, and has a flywheel built with a hub, rim, and six individual spokes.

Jerry’s incredibly small miniature steam engine is mounted on a stand that allows it to be run when compressed air is supplied to the fitting. This is an oscillating engine, unlike Mr. Ahmed’s horizontal steam engine, so the two are not a direct comparison. Either way, it makes for an interesting discussion.

Jerry’s miniature steam engine is .40”-long. (For reference, the width of George Washington’s face on the US quarter is .50”.) The flywheel is just .25” in diameter. The engine has a bore of .059” and a stroke of .060”. Visitors of the Miniature Engineering Craftsmanship Museum can find Jerry’s incredible steam engine perched underneath a magnifying glass, as the details are simply too difficult to see with the naked eye.

Exhibit added: January 15, 2008 - Last modified: June 22, 2023

Presented by The Joe Martin Foundation for Exceptional Craftsmanship