Robert Eastman and Robert Jaquith received an 1820 patent for an inserted-tooth circular saw for a clapboard machine. From 1820 through 1831 this firm manufactured their clapboard machine, plus circular sawmills and water wheels, the clapboard machine selling for $40. In 1832 Eastman moved to Concord, NH, and continued to manufacture under his own name.

All available evidence suggests that Robert Eastman invented the insertible circular saw tooth in about 1820. This was a key innovation in making practical a circular sawmill that could cut larger logs. Eastman also did experiments that led to him greatly reducing the number of teeth in a sawblade, which reduced friction and hence heat-induced distortion of the sawplate. The development of the inserted tool was part and parcel of this effort to reduce distortion of the sawplate. Each sawblade took four inserts, and each insert had a pair of saw teeth, for a total of eight teeth per sawblade. The sawblades were 20 inches diameter.

After seeing Eastman and Jaquith's 'Clapboard Machine' in operation in 1823, a gentleman from South Carolina visiting in Brunswick wrote that 'the machinery, though simple, is so constructed that it will cut two clapboards in a minute, regulate itself without any manual labor, and cut from a block, two feet in diameter, one hundred and twenty clapboards. These are found much superior to rifted clapboards.'"

Information Sources

• Eastman and Jaquith received an 1820 machine for a circular saw for making clapboards. Eastman received other patents, including one for a firearm, and two for water wheels.
• According to a research paper from Old Sturbridge Village, Robert Eastman and Josiah Jaquith manufactured clapboard machines between 1820 and 1831. From 1832 until at least 1835, Eastman operated on his own from a shop in Concord, NH. The paper gives the following references for Eastman & Jaquith:
  • Eastman's Rotary Sawing Machine," The American Journal of Science and Arts, V (1822), 146-152
  • Henry Putnam, A Description of Brunswick, Me. In Letters by a Gentleman from South Carolina To a Friend in That State (Brunswick, 1823), pp. 17-18
  • George A. Wheeler and Henry W. Wheeler, History of Brunswick, Topsham, and Harpswell, Maine Including the Ancient Territory Known as Pejepscot (Boston, 1878), pp. 570-571
  • Guy S. Rix, comp., History and Genealogy of the Eastman Family of America (Concord, N. H., 1901), pp. 152-153, 301
  • New Hampshire Patriot and State Gazette, September 14, 1835.
  • Eastman and Jaquith received a patent on March 16, 1820. Edmund Burke, comp., List of Patents for Inventions and Designs Issued by the United States from 1790 to 1847 (Washington, 1847), pp. 265-282.
• 1857 article, On the conversion of wood by machinery (PDF), by Guilford Lindsay Molesworth. page 22.

  Mr. Eastman's saw, for cutting weather boards out of the log, had only four teeth, as the saws with the ordinary number of teeth were found to heat, when they were completely buried in the wood. This saw was 20 inches in diameter; the body was formed of an iron plate, one-eighth of an inch thick, with dove-tailed notches for four teeth, and was driven with a velocity of 1,200 revolutions per minute.