In 1906, blacksmith Niels C. Simonsen set up operations in Sioux Rapids, Iowa, as N. C. Simonsen. By 1911 he was manufacturing and selling a hot-trimming shear for blacksmithing and farm use. By 1914 the business was using the name Simonsen Iron Work and by 1924 they were making products related to auto and truck repair, and were continuing to make hot-trimming shears in two sizes. A 1931 patent was granted to Niels C. Simonsen and assigned to Simonsen Iron Works, "A copartnership consisting of Niels C. Simonsen and F. M. Ingram".

The Simonsen business continued for more than a century. At some point they expanded to nearby Spencer, Iowa. They were acquired by Cycle Country in 2005, one of their major customers for metal fabrication work. It operated as Cycle County Accessories until 2012 when the name was changed to Simonsen Iron Works. By that time their focus had shifted from manufacturing work to job-shop work. They seem to have suffered a closure in 2012 or '13 and were then acquired by agricultural equipment maker Thurston Manufacturing Co. of Thurston, Nebraska, which continued the job-shop work and added a product line: the ChuckWagon Mobile Grilling Systems, which was sold under the Simonsen Iron Works name. In January 2019 Thurston filed for bankruptcy protection, shortly afterwards they closed the Spencer plant and moved its operations to Thurston, NE.

Information Sources

• March 1911 The Blacksmith and Wheelwright. "Hot Trimming Shear.—Almost every blacksmith shop could use Simonsen's Hot Trimming Shear to advantage. It will be found illustrated and briefly described in our advertising department and is manufactured by N. C. Simonsen, Sioux Rapids, Iowa. It will be found very useful in trimming cultivator shovels and plow points and also for cutting off hot irons usually cut on the hardy, or with a chisel and sledge. This shear is sold at a very reasonable price. But write for illustrated circular and prices and mention the Blacksmith and Wheelwright.
• 1914-15 Iowa State Gazetteer and Business Directory lists Simonsen Iron Works of Sioux Rapids as blacksmiths and makers of blacksmiths' shears.
• February 1924 American Blacksmith and Motor Shop.

  SIMONSEN'S ADD-VISE AND GROOVETTE

  Mr. N. C. Simonsen of the well-known Simonsen Iron Works announces two new additions to their lines of machines. These are known as Simonsen’s Add-Vise and Simonsen’s Groovette.

  Simonsen’s Add-Vise is a portable piston vise which is held in the ordinary vise for holding pistons. It is announced as being sold at a very low cost and makes a piston holder out of any vise.

  Simonsen’s Groovette is described as a hand lathe for cutting piston grooves. Its work is said to be equal to the work done on a five hundred dollar power lathe and is a boon to the mechanic in stopping oil pumping. This tool sells for a very low price.

  These two new tools should be of great interest to our readers. Full information, prices and specifications may be had by writing the Simonsen Iron Works, Sioux Rapids, Iowa.

• November 1927 Popular Science has a classified ad, "Manufacturer with national sales connection desires additional items for hardware or automobile trade. Simonsen Iron Works, Sioux Rapids, Iowa."
• 1934 Engineers lists "Simonsen Iron Works (So-Boss cow hobble, victor motor support, Simonsen all-steel shears, brake lining centers) Gen. Offices, Sioux Rapids, Ia. Plant, Sioux Rapids, Ia. Partnership, N. C. Simonsen, F. M. Ingram".
• A 1945 issue of Farm Implement News Buyer's Guide lists Simonsen Iron Works as makers of "Poultry Holders (for scales)", wagon bolster stakes (steel), and "Wagon Hounds (or Hawns—Adjustable)".
• 1947 State of Iowa Official Register lists authorizations for companies to issue stock, including, on 1945-11-12, Simonsen Iron Works, Inc., Sioux Rapids.
• 1952-02-16 Carroll Daily Times Herald. "N. C. Simonsen, Manufacturer, Dies / SIOUX RAPIDS. IA.— N. C. Simonsen, 67, founder, of the Simonsen Iron Works in Sioux Rapids, died at his home Friday of a heart ailment. He had been in ill health for several years, although he remained active in the business which he founded in 1906."
• August 1971 Field & Stream has an ad from Simonsen Iron Works, Inc. for their "Katchmaster" fishing-rod holder, for mounting on land, dock or boat, priced at $4.95 each.
• The archive.org archive of 1999-2005 simonsenironworks.com provides some snapshots of Simonsen Iron Works' operations during that time.
• 2005-04-12 article in Lawn & Landscape, Cycle Country to Acquire Assets of Simonsen Iron Works.
• Article in 2013-03-17 issue of Sioux City Journal, Spencer, Iowa, business draws on long history of success.
• 2013-05-20 Farm Equipment, Thurston Manufacturing Company Acquires Simonsen Iron Works.
• Article in 2019-03-08 Spencer Signal, Simonsen Iron Works facility closing.
• 2019-03-11 Farm Equipment article, Following Bankruptcy Filing, Thurston Mfg. to Close Simonsen Iron Works.