Lowell (/ˈloʊəl/) is a city in Massachusetts, in the United States. With Cambridge, Lowell is one of two traditional seats of Middlesex County. With an estimated population of 115,554 in 2020,[4] it was the fifth most populous city in Massachusetts as of the last census, and the second most populous in the Boston metropolitan statistical area.[5] The city also is part of a smaller Massachusetts statistical area, called Greater Lowell, and of New England's Merrimack Valley region.
Incorporated in 1826 to serve as a mill town, Lowell was named after Francis Cabot Lowell, a local figure in the Industrial Revolution. The city became known as the cradle of the American Industrial Revolution because of its textile mills and factories. Many of Lowell's historic manufacturing sites were later preserved by the National Park Service to create Lowell National Historical Park.[6] During the Cambodian genocide, the city took in an influx of refugees, leading to a Cambodia Town and America's second largest Cambodian-American population.[7]
Lowell is home to two institutions of higher education. UMass Lowell, part of the University of Massachusetts system, has three campuses in the city. Middlesex Community College's two campuses are in Lowell and in the town of Bedford, Massachusetts. Arts facilities in the city include the Whistler House Museum of Art, the Merrimack Repertory Theatre, the Lowell Memorial Auditorium, and Sampas Pavilion. In sports, the city has a long tradition of boxing, hosting the annual New England Golden Gloves boxing tournament. The city has a baseball stadium, Edward A. LeLacheur Park, and a multipurpose indoor sports arena, the Tsongas Center, both of which have hosted collegiate and minor-league professional sports teams.
A knife (plural knives; from Old Norse knifr 'knife, dirk'[1]) is a tool or weapon with a cutting edge or blade, often attached to a handle or hilt. One of the earliest tools used by humanity, knives appeared at least 2.5 million years ago, as evidenced by the Oldowan tools.[2][3] Originally made of wood, bone, and stone (such as flint and obsidian), over the centuries, in step with improvements in both metallurgy and manufacturing, knife blades have been made from copper, bronze, iron, steel, ceramic, and titanium. Most modern knives have either fixed or folding blades; blade patterns and styles vary by maker and country of origin.
Knives can serve various purposes. Hunters use a hunting knife, soldiers use the combat knife, scouts, campers, and hikers carry a pocket knife; there are kitchen knives for preparing foods (the chef's knife, the paring knife, bread knife, cleaver), table knives (butter knives and steak knives), weapons (daggers or switchblades), knives for throwing or juggling, and knives for religious ceremony or display (the kirpan).[4]
Knife making is the process of manufacturing a knife by any one or a combination of processes: stock removal, forging to shape, welded lamination or investment cast.[1] Typical metals used come from the carbon steel, tool, or stainless steel families. Primitive knives have been made from bronze, copper, brass, iron, obsidian, and flint.[1]
Materials for blades
Main article: Blade steel
Different steels are suited to different applications. There is a trade off between hardness, toughness, edge retention, corrosion resistance, and achievable sharpness. Some examples of blade material and their relative trade offs:
The newest powder metallurgy steels can be made very hard, but can quickly wear out abrasives and tooling.
A blade made from low carbon or mild steel would be inexpensive to produce and of poor quality. A low carbon blade would be very hard to break, but would bend easily and be too soft to hold an edge. High carbon (or high alloy, in some listings) can take a much higher hardness but must be tempered carefully after heat treatment to avoid brittleness.
Unusual non-metallic materials may also be used; manufacturing techniques are quite different from metal:
The natural volcanic glass obsidian can achieve a nearly molecular edge (high achievable sharpness) and only requires Stone Age technology to work,[2] but is so brittle that it cannot maintain that sharpness for very long. Also the entire blade is very easy to break by accident. Obsidian is used to make extremely sharp surgical scalpels.[3]
Ceramic knives hold their edge for a long time, but are brittle.
Blade making process
Initial forging
A blacksmith shop in Ketchikan, Alaska specializing in knife making.
The initial shaping of a knife is done through forging or blanking. Steel can be folded either to form decorative pattern welded steel or to refine raw steel, or as the Japanese call it, tamahagane. Grain size is kept at a minimum as grain growth can happen quite easily if the blade material is overheated.[4]
In a mass production environment, or in a well equipped private shop, the blanking process is used to make "blade blanks." This can be achieved by a number of different methods, depending upon the thickness of the material and the alloy content of steel to be cut. Thinner cross section, lower alloy blanks can be stamped from sheet material. Materials that are more difficult to work with, or jobs that require higher production volume, can be accomplished with water jet cutters, lasers or electron beam cutting. These two lend themselves towards larger custom shops. Some custom knife makers cut their blanks from steel using a metal-cutting bandsaw.
Knife makers will sometimes contract out to a shop with the above capabilities to do blanking. For lower production makers, or lower budgets, other methods must suffice. Knife makers may use many different methods to profile a blank. These can include hacksaws, files, belt grinders, wheel grinders, oxy-acetylene torches, CNC mills, or any number of other methods depending on budget.
Grinding
Main article: Grind
Belt grinder for knife making
If no power equipment is available, this can be done with files if the piece of steel has not yet been hardened. Grinding wheels, or small belt sanders are usually what a beginner uses. Well equipped makers usually use a large industrial belt grinder, or a belt grinder made specifically for knife making. Pre-polish grinding on a heat treated blade can be done if the blade is kept cool, to preserve the temper of the steel. Some knife makers will use a coolant mist on the grinder to achieve this.
Heat treatment
Main article: Heat treatment
Methods of heat treatment: atmosphere furnace, molten salt, vacuum furnace, coal (coke) forge, oxy/acetylene torch. Quenching after heat treatment differs according to type of metal and personal preferences. Quenching can be done with oil, animal tallow, water, air, or brine.
Blade finishes
The finish quality of the blade is determined by the Grit of the finishing grind. These can range from a low-shine 280-320 grit finish to a mirror-shine. The high polish shine can be accomplished by buffing with chrome oxide (ex. white chrome, green chrome), hand rubbing with extremely fine wet-or-dry abrasive paper, or with a Japanese water-stone, which has an approximate grit of 10,000-12,000. Most high quality manufactured knives have about an 800 grit finish.[citation needed]
Attachment for small wheels used in making handles for knives.
Handle making process
Handle making can be done in several different ways depending on the tang of the knife. Full tang knives usually have handle scales either pinned, riveted, or screwed on to the tang itself while knives without a full tang may be inserted into a solid handle and then attached in one of the previously stated methods. Handle materials can range from natural materials including wood or elk horn to man-made materials like brass, plastic, polymer or micarta. A knife makers grinder may have additional attachments for making knife handles, such as small diameter contact wheels.