Louis John Hardt 1893 Patent
The following excerpts are from Roger Smith's Patented Transitional and Metallic Planes in America 1827-1927 Volume I
"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.
 There are three known sizes/types of Hardt Patent planes, the 22 inch jointer, 11 inch smoother and the block plane. All are based on Sargent planes and in fact many of the components are Sargent made and labeled. |  Interestingly, Hardt used Sargent components (frog, iron, cap iron and likely the tote and knobs) and cast the bottom in two pieces. Everything behind the mouth looks Sargent but the front is all Hardt. The lever cap was likely also cast by him as his name appears on the back. |  The smooth plane produced by Hardt is 11 inches in length, has a 2 3/8 inch iron and is likley based on the Sargent 410. |  |
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 Two-piece construction, reminicent of the Leonard Bailey split frame design and utilizing the same general pricipal of adjusting based on relationship of the moveable front and stationary back sections. However, Hardt's patent is designed to change the width of the mouth and change depth of cut by raising/lowering the front section. The former it does quite well, the latter, not so much. |  The back of all the planes are typically Sargent. |  The Hardt block plane uses a single brass knob to secure the front casting which hand adjusts fore and aft to change the width of the mouth and, as with the larger planes, the plane of the bottom. The depth adjuster refines depth of cut |  Hardt's jointer is likely based on the Sargent 422 as it's dimensionally the same. |
 From a performance perspective, in a normal configuration, each performs quite well using the brass adjusting knob for depth control. Using the front adjusting system to open and close the mouth is a imprecise and somewhat finicky process that takes practice and finese. The craftsman's technique plays a very large part in success. |  All three sizes are well built and refined. Fit and finish appears detailed and clean. |  Note the interesting configuration of the mouth with the small notches in each corner. The smooth planes seem suceptable to corner fracturing most likely due to the thinness of the casting at that point. Also note that the edges of all three sizes are champhered for reasons know only to Mr. Hardt. |  |
 Note that Hardt's name is cast into the back of the lever cap and in front of the knob while the early Sargent logo is stamped atop the iron. |