"Patent No. 502,906 was granted to Louis John Hardt of Yuba City, California on August 8, 1893. This patent is a prime example of a patent that underwent major change vetween the time it came off the drawing board to when it acutally got into production.

The patent specifications made provision for a wooden plane having a front nose piece that would slide on an inclined plane, thus exposing the cutter for a fine or rough cut."

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"All of the planes known, made under this patent, are of cast iron, and they have the Bailey type adjustment feature. Thus, they actually have two depth adjustments, which is superfluous to say the least. The planes are well made and certainly interesting to study. The front nose on the bench-size plane is adjusted by means of a thumbscrew in front of the knob to regulate the depth of cut. A wing nut behind the front knob locks thenose into position. The block plane has a locking thumbscrew only. The edges of the sole behind the mouth on all planes have shallow chamfers, full length, to reduce friction."

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"Evidnetly, Hardt had a local foundry cast the beds and nose pieces for these planes. However, he obviously purchased the frogs, cutters, and lever caps, including those on the block planes from Sargent & Company of New Haven, Connecticut. All of the Hardt planes known have the Sargent trademark on the cutters and the February 3, 1891 (Sargent) Patent date stamped on the twisted lateral levers. Hardt and PAT. AUG.8, 1893 are cast on the bed of the nose piece on the bench planes. The same markings are stamped on the heel of the block plane. HARDT is cast underneath the level (sic) cap."

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"Hardt probably machined the castingss, manufactured the rosewood handles and knobs, and assembled the planes with the Sargent parts described. It is not known how many sizes were availale or the number designations used. There are about seven planes known, and as might be expected they are all in California collections." * "The planes were probably produced in one production run only, c1893-4."

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"The information available on Louis Hardt is minimal. He was born in Germany in 1863 and brcame a naturalized American citizen on September 16, 1891. His trade was listed as a carpenter, and his residence was in Yuba City, California. He was not listed in Sutter County registration books subsequent to 1892, indicating that he may have removed from that county sometime in 1893."

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"There were other plane patents issued to Californians, but this is the only patent, actually used, that the author is aware of.  It was probably the only metallic plane ever manufactured in California prior to the 1920s" (Roger Smith; PTAMPIA Vol I pgs 206-207)

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Why these planes never made it to mass production is speculative. Perhaps the small size and remoteness of Yuba City, which was a rural farming community at the time. But considering that it's only about 30 miles from the state capitol of Sacramento, that's not likely. Complexity and expense of production is more likely a reason.The fact that Hardt apparently left the area for some reason gives reason to believe that he recognized his product would not be a marketing success and left for greener pastures. During Hardt's development period around 1893, Sargent was also developing their more successful Shaw's Patent planes and Stanley their Bedrock line. Perhaps Hardt's timiing was just bad or he was hoping that Sargent or Stanley would recognize his advanced design, perceive strong competetion and buy him out at a healthy profit. Whatever the reason for the plane's commercial failure it still is one very interesting concept, though in my opinon, flawed from a practical user standpoint.

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Each plane in the collection has been gently cleaned and the iron sharpened. The block and smooth plane, along with 3 spare blades for the smoother, 2 for the block and 2 additional lever caps for the block were found in a box at an estate sale not far from Yuba City, CA, from which Hardt hailed. Also in the box was a Stiletto draw knife bearing the ectched name of another Hardt family member. Whether or not the estate was that of the Hardt family is a mystery.

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* Though many of the known planes at the time Smith's book was published, were originally found in Sacramento/Yuba City, California area, a number have indeed migrated east of the Mississippi and have appeared in several midwest and east coast tool auctions. It's not known for sure if the number of known Hardt patent planes has increased since the book's publication but at any rate they are "as rare as hens teeth". Those pictured in this article were all found in the former locale. As mentioned above, the smooth plane and block plane were found at an estate sale not far from Yuba City. the jointer plane was also found at an estate sale in Sacramento.