Cold Chisel

Identity

• Names: "cold chisel" is the standard trade and retail name across every source found in Run 443. "Cold" separates it from a blacksmith's hot chisel or hot cut, used on heated iron at the forge (its own entry, Hardy (Hot) Cut, Run 457). "Cold" means unheated metal; it does not make this a general chisel for every hard, cold material. Ilgen's Forge Work (1912) warns that the name does not mean the tool can cut anything, and that temper must suit the intended material [manual, relayed]. No dedicated regional-language name was located in Run 443; that is a checked gap.
• Family / category: a hand-struck steel metal chisel: a steel body with a wedge-ground cutting end, driven by a hammer to cut, shear, split or chip metal softer than its own cutting edge. It sits in the struck-tools family with the nail set, center punch and pin punch, all covered by the consolidated ASME B107.410 standard, which treats metal chisels, brick chisels and pry bars as separate classes [manual, relayed].
• One-line: a hand-struck steel chisel with a hardened and tempered cutting end, ground to a wide (about 60–70°) point angle, used to shear, split or chip metal softer than its edge, such as rivets, bolts and castings.
• Explicitly NOT: a masonry, brick, stone or concrete chisel. CCOHS states: "Do not use cold chisels for cutting or splitting stone or concrete." Mayhew's current cold-chisel page says the tool is for metals softer than its edge and is "Not intended to be used on masonry materials" [manual, relayed]. Also not a wood chisel (established from the other direction by 13+ sibling entries in this corpus, among them Firmer Chisel, Bench Chisel, Paring Chisel, Mortise Chisel and Nail Set), not a pry bar or lever, not a center punch (a marking point, not a cutting edge; see this corpus's Nail Set entry), and not a pneumatic chisel bit (see Lineage).

How NOT to use it

• Not-for: masonry, brick, stone and concrete (CCOHS: "Do not use cold chisels for cutting or splitting stone or concrete"; Mayhew [manual, relayed]); cutting or paring wood; prying or levering. The prying prohibition is a reasoned inference from ASME's separate pry-bar class, not a sentence found stated by name; it is flagged as such.
• Dangerous:
  • Mushroomed head: OSHA 29 CFR 1926.301(c): "Impact tools, such as drift pins, wedges, and chisels, shall be kept free of mushroomed heads." CCOHS explains that the rolled-over metal can break off and send fragments fast enough to injure skin and eyes. OSHA names chisels generally, not "cold chisel" by name.
  • Flying work chips and tool fragments: chips from the work and fragments from a damaged or brittle tool are primary hazards to the user and to anyone nearby. Controls: impact eye protection with side protection, a face shield over it where warranted, a shielded or cleared chip path, and bystanders screened (see Correct use). Safety glasses alone have not always been enough (the 2020 OSHA incident [manual, relayed]).
  • A missed blow to the holding hand: use a holder, tongs or hand guard, keep the hand behind the head, and start with a light locating blow.
  • A shifting workpiece: unsecured work can move, throw the chisel sideways and break out unpredictably. Clamp or support it.
  • Hidden stored energy: cutting into pipe, fittings, fasteners under load or nearby utilities can release pressure, contents or energy. Assess before striking.
  • Spark hazard: steel chisels can spark. In a potentially explosive atmosphere, follow the hazardous-area plan; a spark-resistant alloy chisel does not make the atmosphere safe by itself [manual, relayed].
  • Improvised heat treatment: rehardening or overheating a chisel can make the struck end brittle. Do not improvise it.
• Damaging: the wrong point angle for the metal (too fine on hard stock chips or rolls the edge); cutting material harder than the chisel's rating (the edge chips, and the work can fracture rather than shear); grinding with heavy pressure or without cooling (the temper is drawn); using a chisel on sheet where it stretches and distorts the work.
• Beginner-trap: a fixed working angle instead of laying the bevel on the shearing plane; striking off-centre so the chisel skates; holding the chisel bare-handed close to the blow; working with no vise or support; and continuing with a visibly mushroomed head "because it still cuts fine."
• Lineage-misuse: treating it as a wood chisel; as a masonry chisel; as a pry bar because its wedge profile invites leverage; or swapping it with a pneumatic chisel bit, which is a model-specific machine accessory with its own shank, retainer, rating and instructions.

Correct use

• Genuinely good at: cutting, shearing, splitting and chipping metal softer than its own cutting edge: rivets, suitable nuts and bolt heads, rough chipping and fitting of castings, and slots, grooves, keyways and corners with the matching variant.
• Before you strike (the core sequence):
  • Check both tools. Use only a chisel and hammer in good condition: sharp edge, no mushroomed, chipped, cracked or bent chisel, a sound hammer face and a tight hammer head. CCOHS: "Discard tools that are bent, cracked, or chipped."
  • Check the job. For seized fasteners, pipe, fittings, panels or castings, first confirm the work is not pressurized, energized or holding hazardous contents, and check for nearby utilities, brittle-fracture paths and damage to adjacent parts. "Stubborn metal" is not enough to go on.
  • Secure the work. Clamp it in a vise or hold it on a solid, appropriate support so it cannot shift under the blow. Protect an anvil or vise face with sacrificial material where needed.
  • Choose the hammer (see Matching): the chisel maker's guidance first; otherwise a ball-peen/engineer's hammer whose face is about 3/8 inch larger in diameter than the chisel's struck face [manual, relayed].
  • Protect your eyes and face. Impact-rated eye protection with side protection, every time. Where fragments are likely to be severe, add a face shield over the safety glasses or goggles; a face shield does not replace them (the reviewer's safety note [manual, relayed]; CCOHS names safety glasses, goggles and face shields for struck tools). An OSHA incident report from 2020 records a worker hospitalized after a chisel fragment reached the eye despite safety glasses [manual, relayed].
  • Protect your holding hand. Use a chisel holder, tongs or a hand guard where practical, especially for heavy blows or near obstructions. CCOHS: "Use holders for punches and chisels," and it names a sponge-rubber shield on the chisel shaft as one form of hand protection.
  • Make the chip path safe. Aim chips away from people, glazing, finishes, hoses, wiring and machinery. Clear bystanders or screen them; CCOHS: "Use a screen or shield to protect fellow workers from flying chips."
• While striking: keep the holding hand behind the head, below the line of the blow. Start with a light locating blow. Strike squarely, with the hammer face parallel to the struck face; avoid glancing blows, overstrikes and understrikes. Stop if the work, the support or either tool moves or deforms.
• Working angle, by operation: CCOHS says to hold the chisel for shearing and chipping at an angle that lets the bevel sit flat on the shearing plane. The fixed 45°/90° rule in Run 443 is withdrawn. Operation notes from the Navy's Engine Room Tools, as the reviewer describes them [manual, relayed]:
  • Surface chipping: present the bevel to the intended shearing plane.
  • Round or bar stock: support the work on a protected or sacrificial surface and often cut partway from opposite sides.
  • Sheet and plate: prefer snips, a saw or another controlled process, because chiseling stretches and distorts the sheet. If a chisel must be used, clamp at the cut line and follow a recognized procedure.
  • Cast iron: direct and contain the chips; cast iron chips and breaks out differently.
  • This is not a punch; do not use it to "punch through."
• Retirement and redressing: inspect the struck end before every use. A mushroomed, chipped, cracked, bent or uncertain chisel is out of service until it is redressed to the maker's or original contour by the approved method, or retired. ASME's user guidance, per the reviewer, favours hand filing to original contour, with other methods reserved for trained industrial users [manual, relayed]. If grinding is permitted, CCOHS warns against heavy pressure on the head and says to cool the chisel in water periodically, because heat can remove the temper. Never improvise heat treatment.

✦ Matching

• Does: cuts, shears, splits and chips metal softer than its cutting edge; splits a suitable nut or shears a rivet where surrounding parts are protected; rough-chips and fits castings; cuts slots, keyways, grooves and corners with the matching variant.
• Suits: automotive and machinery repair (rivet and fastener removal), pipe and fitting work after the line is confirmed unpressurized and empty, general metalworking and fabrication, and a seized or rusted fastener that must be split rather than turned out, once the stored-energy and collateral-damage check is done.
• Conditional match: sheet or plate only when a better-controlled method is unavailable (it distorts); cast iron only with chip containment and an operation-specific procedure; fasteners only after confirming the work is unpressurized and de-energized and that damage to adjacent parts is acceptable.
• Kit-fit — pairs with: an appropriate striking hammer, usually a ball-peen or engineer's hammer, chosen by the chisel maker's guidance where supplied; otherwise one whose face is about 3/8 inch (0.375 inch) larger in diameter than the chisel's struck face [manual, relayed], so the face fully covers the struck end. That is a face-size rule, not a hammer-weight rule. Also pairs with a vise or solid support, a chisel holder or hand guard, and impact eye protection.
• Kit-fit — does NOT pair with: a hammer with a damaged, chipped or loose face, or one whose face is smaller than the chisel's struck face. (Run 443's categorical claw-hammer exclusion and hardness-matching explanation are withdrawn as unsourced.)
• Kit-fit — substitutes for: may make rough cuts in metal where a saw cannot be positioned and finish quality does not matter. It is not a general equivalent of accurate sawing.
• Does NOT substitute for: a masonry, brick or stone chisel; a wood chisel; a center punch; a pry bar (the shank is made to be struck along its axis, not levered); or a pneumatic chisel bit.
• Not-for (project-keyed): stone, brick, block or concrete of any kind; wood paring or joinery; layout punching; prying or levering; hardened or tempered steel beyond the chisel's rating, unless the maker expressly rates that pairing.
• Access: simple and cheap, but not beginner-forgiving. A first-timer can use it safely only by following the full sequence in Correct use: secure work, sound tools, the right hammer, impact eye protection, a guarded hand and a safe chip path.
• Revival: the tool a maker reaches for when a project stops being pure woodworking (a seized bolt, a rivet that has to go) and a low-cost way to cut metal without a power tool, inside the controls above.

Anatomy

• Head / struck end: softer and tougher than the cutting end by heat treatment, and chamfered or radiused by geometry; the two do different jobs (see History). Some current makers add an anti-mushrooming cap (Crescent [manual, relayed]).
• Shank / body: usually octagonal or round for grip; tougher and softer than the cutting end. Overall length is model-specific: Mayhew's standard line runs about 5 to 7 inches [manual, relayed].
• Cutting edge: a wedge-shaped point. CCOHS: "The point angle of the chisel should be 70° for hard metals and 60° for soft," and "Grind to a slightly convex cutting edge," so the load starts near the centre and the corners are less exposed. Run 443's note that one product page said "60° angles on both sides" (possibly per-side rather than included) stands as an unresolved framing difference.
• Size grades: sizes are model-specific, stated as blade width × overall length from the catalogue item. Mayhew's standard cold-chisel line gives common blade widths from 1/4 to 3/4 inch on 5- to 7-inch tools [manual, relayed]. The Mayhew 61080 set, per Run 443, holds flat chisels at 1/4, 5/16, 3/8, 1/2, 5/8 and 3/4 inch, cape chisels at 1/4 and 3/8 inch, a half-round-nose at 1/4 inch and a diamond point at 1/4 inch.

Variations (living)

• Flat chisel: the general-purpose form, with a slightly convex edge; used for general cutting and chipping of metal, splitting suitable nuts and shearing rivets. Blade width per the catalogue item (see Anatomy). The Run 443 "3.5-inch typical" figure is withdrawn: it appears to describe a broad brick or masonry chisel, not a metal cold chisel.
• Cape chisel: a narrow blade for cutting slots, grooves and keyways in metal. (The stone and thread-staking uses in Run 443 are withdrawn as unsourced.)
• Half-round / round-nose chisel: a curved edge for curved grooves and oilways, such as in bearings.
• Diamond-point chisel: a pointed, four-sided tip for V-grooves and clearing internal square corners. (The Run 443 "6–16 mm" tip range is withdrawn: it is not tied to an identified model.)
• Spark-resistant alloy chisels (a material variant, not a diamond-point feature): copper-alloy chisels sold as non-sparking for hazardous atmospheres. No tool is literally spark-free; ferrous contamination matters; the hazardous-area controls still apply; and copper-beryllium and similar tools should be redressed only by an authorized service (CS Unitec FAQ [manual, relayed]). The tool alone does not make an explosive atmosphere safe.

Trades

• General metalworking and machining: the core use; hand-cutting castings to size before widespread machine tooling (reduced confidence, see History), and general metal cutting, shearing and chipping today.
• Automotive and machinery repair: seized or rusted bolts, rivets and fasteners, after the stored-energy and collateral-damage check.
• Plumbing and pipe fitting: pipe, fittings and fasteners in tight spots, only once the line is confirmed unpressurized and empty.
• Blacksmithing and fabrication: cold cutting of unheated stock; hot work uses the hot chisel or Hardy (Hot) Cut.
• Masonry: removed. Use a purpose-built masonry, brick, concrete or stone chisel.
• Honest gap: no trade-association specification naming a formal cold-chisel procedure was located in Run 443.

Lineage

• Ancestors (broad family only): copper-alloy chisels are documented from ancient Egypt (UCL Digital Egypt), and UCL also lists a Roman-period iron example [manual, relayed]. The Met holds an Egyptian iron chisel broadly dated ca. 1080–525 BCE [manual, relayed]. These establish that struck cutting tools are very old. They do not show a line of descent to the modern hand-struck metal cold chisel, and this entry does not claim one. The cold chisel as a category is a later ferrous-metalworking tool, defined by cutting unheated metal and by differential heat treatment; when and where that category first appeared is unresolved. A claimed "8000 BCE flint chisel" origin found in one low-authority source in Run 443 is excluded.
• Mechanized analogues: pneumatic chisels (air hammers) drive a chisel-shaped bit with a compressed-air piston. They are machine accessories with model-specific shanks, retainers, ratings and instructions, and must not be swapped with a hand-struck chisel in either direction. No documented historical transmission from the hand tool is claimed here, so they are called analogues, not descendants.
• Contemporaries:
  • Masonry, brick and stone chisels: a separate tool class, not a cousin to borrow from. Brick, block, concrete and stone work goes to a chisel made and rated for that material and operation. (Run 443 sourced the original comparison from a contractor forum and a retail page; the separation now rests on CCOHS, Mayhew [manual, relayed] and the ASME class split [manual, relayed].)
  • Star drill: a struck, rotated rod for making holes in masonry; a different tool and a different material family, named only to keep it apart. Sourced in Run 443 from general how-to content only.
  • Wood chisels: the corpus's standing contrast. A much lower bevel (roughly 25–30°) for paring wood fibre, usually struck, if at all, with a wood or soft-faced mallet.

History

• Broad ancestry, not a chain: ancient copper-alloy and iron chisels belong to the long history of struck cutting tools (see Lineage). The original sentence "Greek and Roman iron chisels by roughly 1000 BCE" is withdrawn: it merged places and periods, and Rome is not a 1000 BCE anchor for the Roman evidence the reviewer consulted.
• Differential heat treatment (what makes it a cold chisel): a conforming steel cold chisel has a hardened and tempered cutting end, a tougher, softer body and struck end, and a controlled transition between them. Navy training material (NAVEDTRA 14250A) describes a hard cutting edge, softer body and tough non-brittle head with a blended transition, and warns against treating the whole chisel alike [manual, relayed]. The 2008 ASME B107.410 metal-chisel text, as the reviewer read it, specifies 53–60 HRC near the cutting edge and caps struck-face hardness at 44 HRC [manual, relayed]. A hard edge cuts; a softer, tougher head is less likely to fracture into brittle fragments under hammer blows. The earlier wording "hardened, through-tempered carbon tool steel" is withdrawn as wrong.
• A pre-machine-tool industrial role: before machine tools were widely available, castings were made close to size and the excess was cut away by hand, with cold chisels among the tools used, a role later largely displaced by powered machining. Run 443 found this in its general sources; the reviewer asks that it be tied to a dated technical source, which this pass could not reach. Carried at reduced confidence.
• The anti-mushroom discipline (struck-face geometry): repeated striking makes the struck end flare ("mushroom") into a rolled-over rim that can break off as a projectile. OSHA and CCOHS name this hazard (see How NOT to use it). The struck face of a conforming chisel is chamfered or radiused to limit mushrooming and spalling; the 2008 ASME text, per the reviewer, specifies a struck-face chamfer of about 45° with a lesser width of about one-tenth of the body-stock size [manual, relayed]. Geometry limits the fragile lip; heat treatment limits brittle fracture. They solve different parts of the problem. The Run 443 "roughly 3/16-inch safety bevel" is withdrawn as a universal figure. No date for when this became trade doctrine was found.

Human side

• Trades: general engineering and machining, blacksmithing, plumbing and pipe-fitting work, automotive repair and metalworking broadly. Not woodworking, and not masonry.
• Named makers, verified in Run 443:
  • Mayhew (Mayhew Steel Products): founded 1856 in Shelburne Falls, MA, originally W.H. Maynard & Company, later H.H. Mayhew Co.; still makes cold chisels, including graduated sets (flat, cape, round-nose, diamond-point). Mayhew describes itself as the oldest punch-and-chisel manufacturer in the United States; that is the company's own claim, not independently established.
  • Wilde Tool Co.: founded 1922 as Wilde Drop Forge and Tool Company in Kansas City, MO, by Otto Froeschl, Paul Froeschl and Henry J. Wilde; moved to Hiawatha, KS in 1955; made bayonets in WWII; carries a cold-chisel line today.
  • J.H. Williams & Co.: founded 1882 as Williams & Diamond, Flushing, Queens, NY; renamed 1887; early drop-forged hand-tool maker whose catalogue included chisels; acquired by Snap-on in 1993.
  • Crescent: sells a 3/8 × 6-1/2-inch cold chisel described as heat-treated, with an anti-mushrooming cap design, and stated to conform to ASME B107.410-2018 [manual, relayed].
  • Named by working machinists in forum sourcing as current good-quality sources: Dasco Pro, Armstrong, Proto and C.S. Osborne. Forum reputation only, lower confidence.
  • Stanley's cold-chisel manufacturing history could not be confirmed in Run 443; a stated gap.
• Forum and trade texture, a real limitation: two Practical Machinist threads ("Cold Chisel Work Ideas, Stories" and "Chipping A Casting with a Cold Chisel — How?") were confirmed to exist in Run 443 but could not be read. A search-snippet paraphrase suggested posters see chisel technique as no longer commonly taught; that is unverified and is not to be cited.
• Famous or individually documented use cases: none found and verified; a stated gap.

Proof of existence

• Smithsonian NMAH, "Cold Chisel," late 19th century (nmah_653116): read directly this pass. Object name "Chisel"; physical description "metal, steel"; tagged Metalworking, Striking & Prizing Tools, Hand Tools; credit line Carl M. Hostrup; no maker named. A dated existence point, not an origin. The reviewer also notes another late-19th-century chisel record in the same collection [manual, relayed]; not identified here.
• US Patent 350,420 (Dillon, 1886): a staple-driving patent that describes its implement as held "after the fashion of a cold-chisel," showing the term and familiar form were established by 1886 [manual, relayed].
• US Patent 1,350,241, "Cold-Chisel," William T. Routh, filed 1919, granted 1920: read in full in Run 443; defines the tool as used "to cut or chip metal by striking the implement with repeated blows with a hammer." It documents one particular handled construction, not the tool's invention.
• US Patent 2,910,771 (1957, Cincinnati Tool Co.): an anti-mushrooming head design, showing the mushroom failure was an engineered-against problem by the mid-20th century (Run 443).
• Smithsonian NMAH nmah_1212997, "Chisel, Cold," circa 1970s: ex-railroad-roundhouse collection, with its paired hammer noted (Run 443). Evidence of later working context. The Run 443 claim that this was the only dated example and that no 19th-century museum example exists is withdrawn.
• Governing standard: ASME B107.410, Struck Tools, consolidating B107.43/.44/.46/.48/.49/.50/.52/.59; current edition B107.410-2018 (R2023), with separate metal-chisel, brick-chisel and pry-bar classes [manual, relayed]. Neither Run 443 nor this pass read the standard; the dimensional and hardness figures above are the reviewer's reading of the 2008 text and are not projected onto the current clauses.
• No CPSC recall specific to hand cold chisels was found in Run 443 (a search-index check, not a live-database query).

References

• {title: "Hand Tools: Struck Tools", site: "CCOHS", url: "ccohs.ca/oshanswers/safety_haz/hand_tools/struck.html", kind: government} — read directly 2026-10-16
• {title: "Cold Chisel, late nineteenth century — nmah_653116", site: "Smithsonian National Museum of American History", url: "si.edu/object/cold-chisel:nmah_653116", kind: museum} — read directly 2026-10-16
• {title: "Cold Chisels, 150 Line", site: "Mayhew Steel Products", url: "mayhew.com/products/cold_chisels_150_line_15010", kind: named_maker} — named by the reviewer; fetch failed 2026-10-16, relayed
• {title: "NAVEDTRA 14250A", site: "U.S. Navy", url: "media.defense.gov/2014/Jun/20/2002655935/-1/-1/1/140620-N-ZZ182-6575.pdf", kind: government} — named by the reviewer; not read this pass, relayed
• {title: "Engine Room Tools", site: "U.S. Navy (via maritime.org)", url: "maritime.org/doc/tools/", kind: reference} — historical training text; named by the reviewer; not read this pass, relayed
• {title: "B107.410-2018 (R2023) — Struck Tools (incorporation of B107.43/.44/.46/.48/.49/.50/.52/.59)", site: "ASME", url: "asme.org/codes-standards/find-codes-standards/b107-410-struck-tools-incorporation-asme-b107-43-b107-44-b107-46-b107-48-b107-49-b107-50-b107-52-b107-59", kind: reference} — 2008 text figures relayed from the reviewer
• {title: "1926.301 — Hand and Power Tools", site: "OSHA", url: "osha.gov/laws-regs/regulations/standardnumber/1926/1926.301", kind: government}
• {title: "Accident report 124881.015 (2020)", site: "OSHA", url: "osha.gov/ords/imis/accidentsearch.accident_detail?id=124881.015", kind: government} — named by the reviewer; not read this pass, relayed
• {title: "3/8 × 6-1/2-inch Cold Chisel (CCOCH38)", site: "Crescent", url: "crescenttool.com/all-tools/striking-struck/punch-chisels/ccoch38-38-x-6-12-cold-chisel", kind: named_maker} — named by the reviewer; fetch budget exhausted, relayed
• {title: "Egyptian iron chisel, ca. 1080–525 BCE", site: "The Metropolitan Museum of Art", url: "metmuseum.org/art/collection/search/552558", kind: museum} — named by the reviewer; relayed
• {title: "Chisels", site: "UCL Digital Egypt", url: "ucl.ac.uk/museums-static/digitalegypt/tools/chisel.html", kind: reference} — relayed via the reviewer's reading
• {title: "Forge Work (1912), William L. Ilgen", site: "Project Gutenberg", url: "gutenberg.org/files/53854/53854-h/53854-h.htm", kind: reference} — named by the reviewer; relayed
• {title: "US350420A (Dillon, 1886)", site: "Google Patents", url: "patents.google.com/patent/US350420A", kind: patent} — named by the reviewer; relayed
• {title: "Non-Sparking Tool FAQ", site: "CS Unitec", url: "csunitec.com/non-sparking-non-magnetic-safety-tools-faq/", kind: named_maker} — named by the reviewer; relayed
• {title: "US1350241A — Cold-Chisel", author: "William T. Routh", site: "Google Patents", url: "patents.google.com/patent/US1350241A/en", kind: patent}
• {title: "US2910771A — anti-mushrooming head design", author: "Cincinnati Tool Co.", site: "Google Patents", kind: patent}
• {title: "Chisel, Cold — nmah_1212997", site: "Smithsonian National Museum of American History", url: "si.edu/object/cold-chisel:nmah_1212997", kind: museum}
• {title: "Mayhew 61080 Punch & Chisel Set", site: "Travers Tool / Mayhew", url: "travers.com/product/mayhew-61080-punch-chisel-set-57-071-159", kind: named_maker}
• {title: "Mayhew — Our History", site: "Mayhew Steel Products", url: "mayhew.com/about/history", kind: named_maker}
• {title: "Wilde Tool — Timeline", site: "Wilde Tool Co.", url: "wildetool.com/about-us/timeline", kind: named_maker}
• {title: "J.H. Williams Tool Group", site: "Wikipedia", url: "en.wikipedia.org/wiki/J.H._Williams_Tool_Group", kind: reference}
• {title: "cold chisel", site: "Wiktionary", url: "en.wiktionary.org/wiki/cold_chisel", kind: reference}
• {title: "Cold Chisel — technical/product page", site: "Tameson", url: "tameson.com/pages/cold-chisel-tool", kind: named_maker}
• {title: "Electric/Air Chisel — technical/product page", site: "Tameson", url: "tameson.com/pages/electric-air-chisel", kind: named_maker}
• {title: "Chisel", site: "Wikidwelling/Fandom", url: "wikidwelling.fandom.com/wiki/Chisel", kind: reference}
• {title: "What Are the Different Types of Cold Chisel Tip", site: "Wonkee Donkee Tools", url: "wonkeedonkeetools.co.uk/chisels/what-are-the-different-types-of-cold-chisel-tip", kind: reference}
• {title: "What Are the Different Parts of a Chisel", site: "Wonkee Donkee Tools", url: "wonkeedonkeetools.co.uk/chisels/what-are-the-different-parts-of-a-chisel", kind: reference}
• {title: "36 Facts About Chisel", site: "Facts.net", url: "facts.net/culture-and-the-arts/visual-arts/36-facts-about-chisel", kind: reference}
• {title: "Air hammer (fabrication)", site: "Wikipedia", url: "en.wikipedia.org/wiki/Air_hammer_(fabrication)", kind: reference}
• {title: "Air Tool Chisels", site: "JB Tools", url: "jbtools.com/air-tool-chisels", kind: named_maker}
• {title: "Mason or cold chisel, what is the difference?", site: "ContractorTalk forum", url: "contractortalk.com/threads/mason-or-cold-chisel-what-is-the-difference.123753", kind: forum}
• {title: "Masonry Chisel vs Cold Chisel", site: "Dweller Power", url: "dwellerpower.com/masonry-chisel-vs-cold-chisel", kind: reference}
• {title: "Cold chisels", site: "Appropedia", url: "appropedia.org/Cold_chisels", kind: reference}
• {title: "Chisel Safety — Toolbox Talk", site: "IAMU", url: "cdn.ymaws.com/members.iamu.org/resource/resmgr/Toolbox_Talks/Chisel_Safety.pdf", kind: reference}
• {title: "Good quality files and chisels", site: "Practical Machinist forum", url: "practicalmachinist.com/forum/threads/good-quality-files-and-chisels.278550", kind: forum}
• {title: "Cold Chisel Work Ideas, Stories (thread found, direct fetch failed — flagged gap)", site: "Practical Machinist forum", url: "practicalmachinist.com/forum/threads/cold-chisel-work-ideas-stories.182587", kind: forum}
• {title: "Chipping A Casting with a Cold Chisel - How? (thread found, direct fetch failed — flagged gap)", site: "Practical Machinist forum", url: "practicalmachinist.com/forum/threads/chipping-a-casting-with-a-cold-chisel-how.139078", kind: forum}
• {title: "Nail Set (Nail Punch) (Haft Tool Corpus — sibling citation and center-punch-distinction basis)", url: "internal corpus file, Nail Set (Nail Punch)", kind: reference}
• {title: "Firmer Chisel (Haft Tool Corpus — sibling citation basis)", url: "internal corpus file, Firmer Chisel", kind: reference}

The reviewer's corrections (10)

• BLOCKER — 1. Remove masonry from the cold-chisel identity and matching data — Exact claim: The family is “metal/masonry cutting chisels”; the tool is “ground ... so it can shear or chip metal, rivets, and masonry”; it is “genuinely good at” masonry; and it suits “masonry demolition and modification.”
• BLOCKER — 2. Correct the hardening and tempering model — Exact claim: The modern tool is “hardened, through-tempered carbon tool steel”; the head is “deliberately left softer, or lightly chamfered, than the hardened cutting tip”; and a ball-peen hammer's hardened face is “matched to a cold chisel's hardened head.”
• BLOCKER — 3. Replace the hammer-size and pairing rules with the actual struck-tool rule — Exact claim: “The hammer's striking face should be sized at least roughly twice the chisel head's diameter”; a ball-peen hammer is matched by hardness; a claw hammer categorically “does NOT pair with” the chisel.
• BLOCKER — 4. Add a complete chip, hand, bystander, and workholding safety sequence — Exact claim: “Beginner-usable with real safety instruction,” followed mainly by eye protection, mushroom inspection, bevel choice, and avoiding off-center blows.
• SHOULD-FIX — 5. Replace the universal 45°/90° technique with operation-specific geometry — Exact claim: “Hold the chisel at roughly 45° ... when shaving” and “closer to 90° ... when punching straight through or chipping directly downward.”
• SHOULD-FIX — 6. Correct dimensions and variant claims — Exact claim: A flat chisel has a “wide beveled edge (roughly 3.5\" typical on a full-size flat chisel)”; cape chisels are also for stone and for staking bolt threads; diamond-point chisels have “roughly 6–16 mm” tips and non-sparking versions.
• SHOULD-FIX — 7. Rebuild the historical lineage without chronology collapse — Exact claim: Egyptian copper/bronze chisels were “succeeded by iron chisels in Greece and Rome by roughly 1000 BCE”; steel hardening/tempering is presented as the direct fix that creates the modern form.
• SHOULD-FIX — 8. Correct the museum gap and evidence hierarchy — Exact claim: The circa-1970s railroad-roundhouse chisel is “the only physical/dated example independently confirmed”; “no 18th- or 19th-century dated museum example was found.”
• SHOULD-FIX — 9. Fix the anti-mushroom maintenance wording — Exact claim: A “roughly 3/16\" safety bevel” and re-grinding are presented as a general maintenance prescription.
• MINOR — 10. Narrow the air-chisel lineage claim — Exact claim: Pneumatic bits have a “different hardness/impact profile” for “rapid, lower-per-blow-energy” impacts and are descendants of the hand cold chisel.