today is May 19, 2022

Here we are in the future, thinking we’re so fancy and cutting edge with mega-scale 3D printers that can extrude complete, ready-to-occupy buildings, only to find out that some clever inventor came up with essentially the same idea back in the 1930s.

The inventor in question, one [William E. Urschel] of Valparaiso, Indiana, really seemed to be onto something with his “Machine for Building Walls,” as his 1941 patent describes the idea. The first video below gives a good overview of the contraption, which consists of an “extruder” mounted on the end of a counterweighted boom, the length of which determines the radius of the circular structure produced. The boom swivels on a central mast, and is cranked up manually for each course extruded. The business end has a small hopper for what appears to be an exceptionally dry concrete or mortar mix. The hopper has a bunch of cam-driven spades that drive down into the material to push it out of the hopper; the mix is constrained between two rotating disks that trowel the sides smooth and drive the extruder forward.

The device has a ravenous appetite for material, as witnessed by the hustle the workers show keeping the machine fed. Window and door openings are handled with a little manual work, and the openings are topped with lintels to support the concrete. Clever tools are used to cut pockets for roof rafters, and the finished structure, complete with faux crenellations and a coat of stucco, looks pretty decent.

But [Mr. Urschel] wasn’t one to rest on his laurels, for as the second video shows, by the late 1940s he had made some improvements to the machine. The extruder design had been streamlined, and the number of potentially dangerous pulleys and belts had been reduced. He also added the ability to angle the boom relative to the mast, letting new courses corbel in over lower courses. The beehive-shaped structure that resulted was pretty charming, even if it needed manual finishing for the very top. Equally charming are the antics of helpers [Larry], [Curly], and [Moe]. It was also good to see that the original building was still standing a decade or more later, although the buildings no longer appear to be standing, at least judging by a quick look at Valparaiso, Indiana on Google Maps.

Granted, [Mr. Urschel]’s design was pretty limited, and we’ve far surpassed his vision by 3D-printing all kinds of structures, from complete castles to wind turbine towers. But there’s no denying that he got there before we did, and it took some pretty clever hacking to do it.

1930s wall building machine

Wall building machine, circa 1940s

Thanks to tipline stalwart [Keith Olson] for the heads-up on this one.