Daniel Chapman Stillson Daniel Chapman Stillson Daniel Chapman Stillson (March 25, 1826 - August 23, 1899) was an American inventor. He invented the modern adjustable pipe wrench. He was born March 25, 1826 in Durham, New Hampshire. He was the son of William Stillson and Nancy Chapman. He married Ellen Raynes Davis on April 18, 1855. He was a machinist during the American Civil War and served on David Glasgow Farraguts first voyage as a vice admiral. At the end of the Civil War, Stillson returned to Charlestown, Massachusetts, and eventually he moved to Somerville, Massachusetts. He then worked as a machinist at
Tool steel to the water-hardening class. These alloys increase the steels' hardenability, and thus require a less severe quenching process and as a result are less likely to crack. They have high surface hardness and are often used to make knife blades. The machinability of the oil hardening grades is high but for the high carbon-chromium types is low. This series includes an O1 type, an O2 type, an O6 type and an O7 type. All steels in this group are typically hardened at 800°C, oil quenched, then tempered at <200°C. The first air-hardening-grade tool steel was mushet steel, which was known