Diamond Calk Horseshoe Company

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The Diamond Calk Horseshoe Company was founded in 1908 by Otto Swanstrom, a blacksmith operating in Duluth, Minnesota. As the name suggests, the company was formed to make calks and horseshoes, and their initial product was a patented insertable calk for horseshoes. (A calk is a gripping bit on a horseshoe, added for better traction on ice or slippery surfaces.) In 1910 the company built a factory at 4630 West Third Street in Duluth.

Diamond was very successful in their calk and horseshoe business, but as the tractor and automobile reduced the need for horses and horseshoes, the company turned its forging skills to the production of adjustable wrenches.

By 1921 Diamond Calk had become a prosperous business employing 150 workers and producing drop-forged railroad supplies and wrenches, in addition to their line of calks and horseshoes.

Initially manufacturing horseshoes with a special type of calk to improve the animals’ foothold on slippery surfaces, the company successfully adapted to the development of motorized transport for the masses and produced a range of adjustable wrenches and pliers from the 1920s. The family-owned company was sold to the Triangle Corporation in 1981; Triangle itself was eventually sold to Cooper Tools.

In 1994, the last workers vacated. The building was demolished in 1996.

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