Cordless Brushless Angle Grinder

identity

one-line: A handheld, battery-powered right-angle grinder with a brushless motor, intended for the grinding, cutting, sanding or wire-brushing operations expressly permitted by the exact model and fitted accessory — metal and masonry work with no cord and no mains tether. Its control electronics are capable of supporting model-specific electronic protections (on some models: kickback detection, electric brake, restart protection, drop control, soft start). Confirm the exact model's manual; never infer brake, restart protection, drop control, constant speed or kickback detection from brushless motor type alone [A-BL, E-BOSCH, E-BOSCHLIM].

name & scope. Sold as the cordless angle grinder, battery grinder, brushless grinder, or by platform shorthand — "the M18 FUEL grinder," "the FlexVolt grinder," "the XGT grinder," "the LXT grinder" [H-MILW, H-DEWALT, H-MAKITA]. "Cordless" (power source) and "brushless" (motor commutation) are separate attributes that converged. Early cordless grinders were brushed: Makita's 7.2 V 9500D is documented as a cordless grinder by a parts record dated 1985 [manual, relayed] [H-MAKITA9500, H-USITC], and Metabo announced its own first cordless angle grinder, the brushed W18LTX, in 2011 [H-METABO]. Brushless motors followed (Milwaukee 2013 and Makita 2014 are the earliest examples found, below). Neither term specifies wheel capacity, switch type, guard, brake, kickback detection, restart protection, variable speed or extraction interface. (Manufacturer "corded replacement" or "corded-equivalent" statements are model- and test-specific marketing claims; runtime, duty cycle, battery temperature, wheel size and application still differentiate the cordless form from corded for sustained heavy work.) Honest scope line: the corded Angle Grinder is the ancestor and is already built (Run 186); this entry is its battery descendant and carries the corded tool's burst/guard/kickback canon, adding what the battery + brushless platform changes. "Angle grinder," "cut-off/angle grinder" and "dedicated cut-off machine" can fall under different manufacturer instructions and standards scopes.

model fields to store (one record per model, never inferred from the family): manufacturer and model; battery platform and approved packs; rated no-load speed or speed range; wheel/accessory capacity; spindle thread, flange system or X-LOCK; approved operations; approved accessory types; required guard by operation; switch type and lock-on behaviour; restart protection (yes/no); brake (yes/no) and stated stop condition; kickback control (yes/no) and stated trigger and limitations; drop control (yes/no); overload/thermal protection; constant-speed control; extraction or wet-control compatibility; auxiliary-handle configuration.

family / category: Abrading tools — the powered, handheld side, the Angle Grinder's direct descendant on the MOUNTING AXIS (fixed↔handheld) that the corded angle grinder opened in Run 186. A grit member by mechanism (bonded/coated wheels — the family's mainstream), distinguished from its corded parent by power source (battery) and motor type (brushless) — and the brushless motor's required control board is what lets some models carry active protections between the hand and the cut (strand 2).

✦ how NOT to use it — the heaviest section (five misuse classes)

not-for (jobs it should never do):

• Side-grinding with a thin cut-off wheel. Type 1/41 cut-off wheels lack lateral strength; side-loading damages the reinforcement and can shatter the wheel [M-SIDELOAD]. A cut-off wheel cuts in-plane only.
• Using a grinding wheel to cut, or a cut-off wheel to grind, or either under the wrong guard — the guards differ by operation [M-SIDELOAD, M-OSHA].
• Fitting a chainsaw / wood-carving chain disc. The UK Government issued a safety alert and Trading Standards ordered such discs off sale; kickback is violent and uncontrolled [M-CHAIN].
• Fitting a circular-saw blade. A landscaper was killed when a circular-saw blade was fitted to an angle grinder (HSE investigation); there is no way to control depth of cut and the blade jams and kicks back [M-SAW].
• Cutting any vessel, tank, drum, pipe, vehicle component or enclosed structure whose contents and energy state have not been identified, isolated, cleaned or made safe as required. Residual flammable or toxic contents, pressure, stored energy, fuel, batteries, pyrotechnic restraints and hidden services turn sparks and heat into fire, explosion or release. This is a hard negative match, not a skill question [S-HOTWORK].
• Vehicle extrication or emergency rescue except by trained specialists under their agency's procedure and scene hazard control. No rescue-agency procedure is cited in this entry establishing the grinder as a general extrication match; a general user is never routed here.
• Grinding in a flammable vapour, combustible dust or explosive atmosphere [S-HOTWORK, S-ALU].
• As a precision or one-handed tool — it is a two-handed removal tool, not a fine instrument [M-1HAND].

dangerous (injures the user):

• Accessory burst — an accessory rated below the grinder's speed, a damaged or aged wheel, or a side-loaded cut-off wheel can shatter, throwing fragments at speeds capable of fatal injury [M-BURST, M-SHRAPNEL]. Match rated speed (ANSI B7.1) and inspect before mounting by the accessory maker's method, ring-testing only where it applies (OSHA 1926.303(c)(7) requires inspection and ring testing of abrasive wheels before mounting; Norton limits where a ring test is meaningful [manual, relayed]) [H-ANSI, M-OSHA, M-RING].
• Kickback — the accessory pinches or snags and the tool is driven back toward the operator faster than a person reacts [M-KICK]. Some models carry electronic kickback functions with maker-stated response times; they respond to specific events (Bosch: forceful stoppage, not necessarily twist/cant or snagging [manual, relayed]) [E-DEWALT, E-BOSCHLIM]. The controls that matter on every model: secured work, both hands, body out of the kickback path, the accessory in its approved operation.
• Unsecured work — a workpiece held by hand or left loose can grab, spin or shift into the accessory, raising kickback and contact risk. Clamp or fixture it [manual, relayed] [S-TOOLBOX].
• Guard removal — directly implicated in two WorkSafe Queensland fatalities: a worker struck in the chest by a disc fragment from a 9″ grinder fitted with an oversized 14″ disc, guards removed (2016); a worker killed by a metal shard from an unguarded 9″ grinder cutting structural steel (2021) [M-GUARD].
• Inadequate eye and face protection — the peer-reviewed literature documents penetrating facial, cranial and ocular injuries; one study puts the hand as the most-injured part (46.4%), then the head (23.0%) [M-MED]. Primary eye protection (safety glasses or goggles) is required; a face shield is added for the operation, never worn instead. Per the review, OSHA records an injury in which a fragment pierced a face shield when basic eye protection was not worn underneath [manual, relayed] (that record is not separately cited or read here).
• Dust and fumes — respirable crystalline silica from concrete, masonry, stone and tile; hazardous dust and fume from coatings and metals; combustible metal dust. Use wet or extraction controls and respiratory protection as the material and rules require [manual, relayed] [S-SILICA, S-ALU, S-TOOLBOX].
• Sparks, hot fragments and fire — grinding is a spark-producing ignition source; uncontrolled combustibles, vapours or dust can ignite, including out of sight behind or below the work [manual, relayed] [S-HOTWORK].
• Noise and vibration — hearing protection by task; long exposures need the maker's vibration guidance [manual, relayed] [S-TOOLBOX].
• The coasting wheel — on non-braking models the wheel keeps spinning after the trigger releases; a tool set down or carried while coasting cuts what it touches [M-COAST].

damaging (ruins the tool or the work):

• Side-loading a cut-off wheel — even short of shatter, it induces runout, vibration and early failure, and gouges the work [M-SIDELOAD].
• Overloading / stalling the motor or fitting accessories beyond the tool's rating — electronic overload protection on many models cuts the motor out; repeated tripping and heat shorten tool life, and the forum record carries an account of a grinder that "smoked and shut off" after its owner fitted wheels meant for a larger grinder [M-OVERLOAD, HS-FORUM].
• Over-tightening the arbor nut — OSHA: tighten only enough to hold the wheel; over-tightening stresses and can crack it [M-OSHA].
• Letting the battery/tool overheat in sustained heavy cuts — thermal cut-out and pack wear; stop when the pack or tool is hot [S-DEWALTMAN].

beginner-trap (looks fine until it isn't):

• Mounting an accessory rated below the grinder's speed — the commonest burst trigger; an ANSI/OSHA violation [M-BURST].
• Trusting a ring test that does not apply, or skipping inspection of an old wheel. Inspect the exact accessory by its maker's method; ring-test only wheels whose maker says the test applies (an organic-bonded wheel's dull tone does not prove a defect, and an inapplicable test proves nothing about soundness) [manual, relayed] [M-RING, M-1910215]. Norton/Saint-Gobain set storage-age guidance for specific resinoid wheels (suspect after ~2 years; re-inspect) — manufacturer guidance for those wheel types, not a universal OSHA rule; humidity speeds degradation [M-AGE].
• Removing the guard "for visibility" — feels reasonable, precedes the fatalities above [M-GUARD].
• Wearing a face shield without glasses or goggles under it — the shield is a second layer, not the first (above).
• Holding small work in the free hand — clamp it [S-TOOLBOX].
• Leaving the switch locked on so the tool lurches to life when the battery is inserted — what restart protection is built to prevent on the models that have it, and exactly the trap on a model without it [M-ANTIRESTART, E-BOSCH].
• Assuming "brushless" means it brakes, detects kickback or refuses to restart — those are model features; read the manual [E-BOSCH, E-BOSCHLIM].
• Assuming cordless = safer (the false-tameness trap, strand 3) — the same rated-speed class carries the same hazard categories [M-PARITY].
• Grinding near combustibles or in the cut of old paint without checking — sparks travel and coatings can be toxic [S-HOTWORK, S-ALU].

lineage-misuse (treating it like its ancestor or a different tool):

• Treating it like its corded brushed ancestor in how it behaves under load — whether brushless speed control changes the cues an operator feels before a cut-out is an untested question here, not a sourced fact; the safe habit is not to rely on load cues at all, and to stop and reassess at any stall or cut-out [A-BL].
• Treating it as de-energized like an unplugged corded tool — the battery keeps it live; the corded habit "unplug before changing the wheel" must become "remove the battery" [M-LIVE].
• Treating every brushless grinder like the braking, kickback-sensing model you used last — features vary by model [E-BOSCH, E-MILW].
• Confusing it with a Die Grinder — die grinders run far higher speeds on small low-torque accessories; angle grinders run lower speeds with higher torque on large discs; accessories are not interchangeable [M-DIE].
• Treating X-LOCK and threaded accessories as interchangeable because diameter and speed match [A-XLOCK].
• Treating it like a cut-off saw or a chainsaw by bolting on blades it was never built to control [M-SAW, M-CHAIN].

correct use (brief — the workbench holds the deep operation)

Before use — assess the job.

• Identify the material and coating. Concrete, masonry, mortar, stone and tile can release respirable crystalline silica; old or unknown paint and coatings can contain lead or other toxic material; asbestos-containing material must not be disturbed without proper controls; aluminium and mixed-metal dust carry combustible-dust and aluminothermic-reaction cautions [manual, relayed] [S-SILICA, S-ALU]. If the material is unknown, stop and find out.
• Identify the setting. Grinding throws sparks and hot fragments that can start fires. Remove or shield combustibles, check both sides of and below the work, have suitable fire protection to hand, and follow any required hot-work permit or fire-watch procedure. Do not grind where flammable vapour, combustible dust or an explosive atmosphere may be present [manual, relayed] [S-HOTWORK, S-ALU].
• Plan the dust control. For silica-containing materials use manufacturer-compatible wet delivery or a shroud with dust extraction as the manual, the task and applicable rules require; OSHA's construction silica standard (Table 1) specifies water delivery or shrouded extraction for covered handheld-grinder tasks, with respiratory protection in stated circumstances [manual, relayed] [S-SILICA].

Before use — set up the tool.

• Remove the battery before adjustment, inspection, accessory changes, jam clearing, transport or storage — do not trust the trigger lock [M-LIVE, S-DEWALTMAN]. Do not use a damaged, modified, overheated or incompatible pack or charger, and prevent terminal shorting [manual, relayed].
• Match the accessory to the exact tool and operation: operation type, diameter, thickness, arbor/interface (threaded or X-LOCK), flanges, backing pad and guard. The accessory's marked maximum speed must equal or exceed the grinder's rated no-load speed; stress rises with the square of speed, so doubling speed quadruples it [M-BURST, H-ANSI].
• Inspect the accessory. Before every use, inspect the exact accessory by the maker's prescribed method. Perform a ring test only when the wheel type and the manufacturer's instructions say it is applicable (Norton states ring testing is mainly applicable to vitrified-bonded wheels and may not apply because of wheel size, shape or composition; organic-bonded wheels do not give the same clear ring [manual, relayed]) [M-RING, M-1910215]. Do not use any cracked, chipped, wet, dropped, expired (where a shelf life applies), distorted, contaminated or otherwise suspect accessory [M-AGE].
• Guard on and positioned between the accessory and the operator, the right guard for the operation [A-GUARD, M-OSHA].
• Fit the auxiliary handle.
• Secure the work with clamps or a fixture. Never hold the work in one hand while grinding or cutting with the other [manual, relayed] [S-TOOLBOX].
• PPE: wear safety glasses or goggles selected for the hazard (OSHA requires eye protection for abrasive-wheel users, 1926.303(c)(9), re-read this pass) [M-OSHA]; add a face shield when the operation calls for it, never as a substitute for primary eye protection. Use hearing, respiratory, hand, foot and body protection based on the material and task [manual, relayed] [S-DEWALTMAN, S-TOOLBOX].
• After mounting, fit the battery, stand out of the accessory plane, keep bystanders clear, and perform the maker-prescribed no-load test run [manual, relayed] [M-RING, S-DEWALTMAN].

During use.

• Both hands on the tool, secure footing, body positioned outside the accessory plane and the expected kickback path [M-KICK, S-TOOLBOX]. One-handed use is reported as a large share of accidents (FEIN citing NCBI, ~40%; secondary) [M-1HAND].
• Right accessory for the job — grinding wheel at the angle its maker specifies for stock removal; thin cut-off wheel in-plane for cutting, never side-loaded; flap disc for blending; wire cup for stripping [A-VAR, M-SIDELOAD].
• Let it reach full speed before contacting the work; let the brake stop it (if the model has one) or wait out the coast before setting it down [E-BRAKE, M-COAST].
• Keep bystanders and the spark stream controlled; watch for smouldering material during and after the work [S-HOTWORK].

After use. Remove the battery; store accessories as their makers direct; recheck the area for smouldering material where sparks fell [S-HOTWORK, M-AGE].

Electronic controls are mitigation, not permission. Kickback detection, electric braking, restart protection, drop control and overload protection — on the models that have them — reduce specific failure modes and do not detect every kickback mode. They do not replace the guard, side handle, correct accessory, rated-speed match, workholding, two-handed control, PPE or correct body position. Do not test kickback, drop or brake protection by deliberately creating a hazardous event.

matching

does: Grinds, cuts and finishes metal and masonry with the accessories the exact model approves — stock removal, weld grinding, surface prep, cutting rebar, pipe and strut, masonry/tile cutting with diamond products and wet or extraction controls, rust and paint removal with a wire cup (once the coating is known), deburring and blending with a flap disc. The cordless form takes this off the cord: field work, rooftops, scaffolds, remote locations with no outlet — with the same spark, dust and fall hazards. Some models add electronic protections (kickback detection, braking, restart protection, drop control, soft start); these are model fields, not part of the family match.

positive gates (all must be true to match): material and coating identified; accessory approved by both the tool and accessory makers for the material and operation; accessory dimensions, interface and rated speed compatible; correct guard and auxiliary handle available; the work can be clamped or fixtured; spark, fire, dust, noise and bystander controls feasible in the setting; battery condition and runtime suit the job.

suits: Metal fabricators and welders (the core trade). Construction and demolition crews (with silica controls). Masons and tile setters (with wet or extraction controls). Plumbers and HVAC workers cutting pipe and strut of known contents. Automotive and exhaust workers (fuel, batteries and coatings identified first). Foundry workers. Steel and stone sculptors. Hobbyists and mobile-service workers doing intermittent jobs away from power. (Removed in the fix pass: fire and rescue / extrication as a general "suits" line — see specialist-only below.)

kit-fit: Pairs with the corded Angle Grinder (cordless for field and intermittent work, corded for sustained work). Shares platform batteries with other tools in the same brand ecosystem; bare-tool SKUs are the norm (Run 274). Shares the wheel library with the corded grinder only where the model's interface, guard and rating allow: grinding wheels (Type 27), cut-off wheels (Type 1/41), flap discs, wire cups/wheels, diamond products. A compatible extractor or wet attachment for masonry work. The Die Grinder is a related but distinct tool — not a substitute.

not-for / negative gates (any one blocks the match): unknown coating or hazardous substrate (old paint, asbestos-containing material, toxic metals); explosive atmosphere, flammable vapour or combustible dust; energized services; any vessel, tank, drum, pipe, vehicle component or enclosed structure with unknown contents or energy state; chainsaw discs, circular-saw blades, or any accessory not expressly approved by the tool and accessory makers; work that cannot be secured or controlled with two hands; side-grinding with thin cut-off wheels; sustained production duty beyond the model's battery and thermal limits (the corded grinder lives here); fine or precision work better served by a die grinder, file, sander, saw or machine tool.

specialist-only: vehicle extrication or emergency rescue — trained specialist use only, under agency procedure and scene hazard control; never a general-user match.

access: Widely available from hardware chains and tool suppliers; all four dominant cordless platforms (Milwaukee M18, DeWalt FlexVolt/20V MAX, Makita LXT/XGT, Bosch 18V) offer brushless grinder models. The real access question is the battery platform: on a platform, the grinder is often sold bare-tool; buying in, factor packs and charger. Braking, kickback-sensing, dual-trigger and high-voltage models sit at the upper end of the range. (Specific price ranges removed in the fix pass: undated and time-sensitive.) Cordless removes the cord trip/cut hazard but does not reduce accessory-burst or kickback hazard (Run 274).

revival: Not a revival candidate — current-production tool; no collector market found for so recent a generation (Run 274). A used cordless grinder should be checked against the manufacturer's inspection, indicator/self-test, diagnostic and authorized-service procedures, with battery-pack condition checked the same way. Do not provoke a kickback, drop or stall to test a protective function. Check guard, spindle, flanges and handle; missing or modified guards are a disqualifying defect.

anatomy (named parts)

• Body / housing — clamshell shell holding the motor lengthwise; a bevel-gear train at the head turns the drive through 90 degrees to the spindle and may also reduce speed / increase torque; the ratio is model-specific (a battery-grinder patent application describes a reduction ratio of 1.5 to 3.5 [manual, relayed]) [A-REDUCTION].
• Brushless DC motor (the heart of the difference) — permanent-magnet rotor, electronically-commutated stator, no carbon brushes; the controller commutates using the design's rotor-position method (sensored and sensorless implementations exist); named by makers (Milwaukee POWERSTATE, Makita BL) [A-BL].
• Electronic control board (ECB/ESC) — commutates the motor, and on models that have them runs soft start, overload/thermal protection, kickback logic and brake behaviour. The motor cannot run without it, which is why protections are possible (strand 2); which ones exist is set by the model's sensors and firmware [A-BL, E-BOSCH]. (Run 274) Its own heat is a design problem: one patented answer moves the drive board into the handle [H-PAT-BL].
• Spindle / arbor — the output shaft carrying the accessory; commonly 5/8″-11 UNC in the US and M14 in Europe, clamped by an inner flange and an arbor (flange) nut — or, on Bosch/Makita X-LOCK, a snap mount with no nut [A-SPINDLE, A-XLOCK]. Read the exact model's thread or interface; it is not interchangeable.
• Wheel guard — shield deflecting sparks, debris and accessory fragments away from the operator; for portable grinders OSHA 1926.303(c)(5) limits wheel exposure to no more than 180° (re-read this pass), and guard type differs by operation — grinding and cut-off configurations do not share one guard [A-GUARD, M-OSHA].
• Side (auxiliary) handle — threaded into a boss on the gearhead for two-handed control; position options are model-specific [A-PARTS].
• Spindle lock — button that locks the spindle for accessory changes; never pressed while the spindle turns, and used only with the battery removed [A-PARTS].
• Switch — paddle / deadman (runs only while squeezed), slide / lock-on (stays on), or dual-trigger (Milwaukee 2986-20: two triggers must engage) [A-VAR, E-MILW]. Lock-on behaviour and restart protection are model fields.
• Battery pack — 18V / 36–40V / 60V lithium-ion; the tool is live whenever a pack is fitted (strand 3). Use only the maker's approved packs and chargers [A-VAR, S-DEWALTMAN].

variations (living)

• By platform / voltage: 18V (Makita LXT, Milwaukee M18, DeWalt 20V MAX) — the compact-to-mid mainstream, 4.5–5″ wheels; 36–40V (Makita XGT, dual-18V LXT X2) and 60V FlexVolt (DeWalt) — marketed for heavier work [A-VAR, H-DEWALT, H-MAKITA].
• By disc size: 4.5″ (115 mm) — most common, typically ~9,000–11,000 RPM no-load; 5″ (125 mm) — common in Europe; 6″ (150 mm); 7″ (180 mm) and 9″ (230 mm) — large class, high-voltage platforms only, lower rated speeds (~6,000–8,500 RPM) [A-VAR]. Rated speed is a wheel-selection field, not a measure of power.
• By switch: paddle/deadman vs slide/lock-on vs dual-trigger [A-VAR, E-MILW].
• By brake: braking (electric; makers state stop times of ~1–2 s for named models) vs non-braking (the wheel coasts) [A-VAR, E-BRAKE, E-MILW].
• By kickback system: AFT (Makita), KickBack Control + Drop Control (Bosch), E-CLUTCH + Kickback Brake (DeWalt), AutoStop (Milwaukee) — different triggers and stated limitations; not all models have one, and none is documented to catch every kickback mode [E-AFT, E-BOSCH, E-BOSCHLIM, E-DEWALT, E-MILW].
• By mount: standard threaded spindle + flange nut vs X-LOCK snap mount [A-SPINDLE, A-XLOCK].
• By accessory (the accessory makes the job — and only those the exact model approves): Type 27 depressed-center grinding wheel; Type 1/41 thin cut-off wheel; flap disc; wire cup/wheel (the Wire Wheel, Run 200); masonry/diamond products [A-VAR]. Each needs its approved guard, flanges and backing.

trades (where it appears, with trade-specific notes)

Metal fabrication & welding (grinding welds, cutting stock, surface prep — the core trade; hot-work controls apply); construction & demolition (cutting rebar, masonry, fixings — silica controls apply to masonry and concrete); masonry & tile (diamond-product cutting with wet or shrouded extraction controls); plumbing & HVAC (cutting pipe and strut — only pipe whose contents and energy state are known and made safe); automotive (exhaust, body, rust — fuel, batteries and coatings identified first); foundry (gate and riser removal); sculpture (steel and stone shaping); fire & rescue (trained specialist use under agency procedure only). Cross-trade note: the rated-speed, guard, workholding, two-hand and PPE rules are trade-independent — they ride the accessory and the physics, not the trade [HS-USERS, M-BURST].

lineage

ancestors (upstream):

• The corded Angle Grinder (built Run 186) — the direct parent. FLEX's company history documents the Ackermann + Schmitt (now FLEX) DL 9, 1954, as the first high-speed angle grinder placed on the market (manufacturer history claim, not independent museum proof); in German-speaking markets "Flex" became a generic word for the tool, added to the Duden dictionary in 2006 [H-FLEX]. The cordless grinder is this tool with the cord cut and, in its modern form, the motor changed.
• The brushed universal motor → the brushless DC motor. The corded grinder runs a brushed universal motor — a wound armature, a commutator and carbon brushes that wear and arc [A-BL]. The enabling ancestor of the modern tool is the brushless DC motor: a permanent-magnet rotor, electronically commutated by a controller using the design's rotor-position method (sensored — e.g. Hall sensors — and sensorless implementations both exist), no brushes. Trade-press figures put it at ~20–30% more efficient with ~50% longer life (MED, not independently tested) [A-BL]. It is the technical ancestor that let battery grinders compete in professional use.
• The lithium-ion tool battery platform — 18V (Makita LXT, Milwaukee M18, DeWalt 20V MAX), 36–40V (Makita XGT, dual-18V LXT X2), and 60V (DeWalt FlexVolt) [A-VAR, H-DEWALT]. (Run 274) Makita's 40V-max XGT uses the same 3.6 V cell type as its 18V packs, wired 10-series rather than 5-series-2-parallel; Milwaukee's High Output line moved from 18650 to 21700 cells in March 2019; FlexVolt switches 15 cells between series and parallel by tool interface [A-CELLS].

the dated milestones (proof of the descent):

• Earliest cordless grinder found: Makita 7.2 V 9500D — identified in Makita's own instruction manual as a cordless grinder, with a parts record dated 19 November 1985, and listed in a U.S. International Trade Commission record as an existing cordless grinder [manual, relayed] [H-MAKITA9500, H-USITC]. Terminology flag: whether the 9500D's accessories and geometry make it an "angle grinder" or the narrower "cordless grinder" has not been checked here; the earliest cordless angle grinder remains unresolved unless an earlier dated catalogue or production record is found.
• Metabo W18LTX — announced 11 August 2011 (PR Newswire), "Metabo's first cordless angle grinder," an 18V brushed tool with a rotating battery pack, 8,000 RPM [H-METABO]. A Metabo milestone, not a category origin.
• (Run 274) Earliest brushless cordless grinder found: Milwaukee M18 FUEL 2780/2781 — previewed 12 June 2013 (ToolGuyd), shipping October 2013, corroborated by a dated trade-association press-release reprint (27 September 2013) and Pro Tool Reviews (15 November 2013) [H-BLDATE]. These are dated trade reports, not a directly retrieved Milwaukee launch record: the earliest brushless example currently found, not settled category priority. Milwaukee's own "world's first cordless grinder" wording is a manufacturer claim [H-MILW]. A single forum claim of an earlier AEG brushless grinder is unconfirmed and not asserted.
• Makita 18V LXT brushless XAG03M — late 2014, Makita's own press release presenting it as a "true replacement for corded models" (manufacturer positioning) [H-MAKITA14]. (Date note: Run 274 read the release as 31 October 2014; the review describes it as a November 2014 release. To be re-checked.)
• DeWalt FlexVolt 60V DCG414 — announced June 2016, shipping fall 2016 (dated PR Newswire), 9,000 RPM, marketed for work previously done with corded grinders [H-DEWALT].
• Makita 40V XGT GAG01Z — 2021, 8,500 RPM, AFT [H-MAKITA]. FLEX — the originator of the high-speed angle grinder — dates its own first cordless angle grinder to 2017 (L 125 18.0-EC) and its first brushless to 2021 [H-FLEXCORD]; this does not imply FLEX or Metabo originated the cordless category.

contemporaries / siblings:

• The corded Angle Grinder — the still-living parent; the two coexist, the cordless taking field/portable and intermittent work and the corded the sustained work.
• The Die Grinder (Run 188) — the small high-RPM handheld cousin on the same ANGLEKIN/DIEKIN branch; cordless brushless die grinders share platforms and electronics but run far higher RPM on far smaller accessories (lineage-misuse below).
• The Cordless Carbide Metal-Cutting Circular Saw (Run 196) — the tooth-side twin (strand 1).

descendants / specialised forms (downstream):

• The brake / dual-trigger grinder — e.g. Milwaukee's M18 FUEL Braking Grinder line and the Dual-Trigger 2986-20 (the maker states both triggers must engage before the wheel spins, with a fixed side handle, AutoStop, and a stated brake stop of one second or less) [manual, relayed] [E-MILW]; FEIN's Protago, which FEIN describes as designed to prevent one-handed use [M-1HAND]. Model-level features, not family traits.
• The quick-change mount (X-LOCK) — Bosch's (and compatible Makita) push-and-snap wheel interface, no flange nut or spanner [A-XLOCK]. X-LOCK and threaded accessories are not interchangeable merely because diameter and speed ratings match.
• The connected grinder (AWS) — Makita's Auto-Start Wireless System, in which the grinder wirelessly commands a compatible extractor to start and stop; the extractor has its own power source [manual, relayed] [E-AWS]. The electronics that make protections possible also become a connectivity platform.

TREE NOTE (Run 201 — light inline touch, NOT a refresh). Per the working discipline, the _Abrading Family — Lineage Tree gets a light inline touch this same run — promote the cordless / brushless angle grinder from the Angle Grinder's ANGLEKIN ghost ("CORDLESS / BRUSHLESS angle grinder — false-tameness descendant") to a built MEMBER node hung off the Angle Grinder by a solid descent link; add a dashed CORDLESS-DEMOCRATIZATION rhyme link to the Cordless Carbide Metal-Cutting Circular Saw (the tooth-side twin, strand 1); trim the ANGLEKIN ghost (its grit-side cordless item is now built; the "bonded wheel on a pivoting arm" item remains ghosted); add ONE node-table row; bump counts (covers_entries 30→31; members twenty-six→twenty-seven). The genuinely-new move to badge: the grit-side cordless-democratization twin of Run 196; the family's first member whose motor requires electronics between the hand and the cut, letting some models carry active protections (a new PASSIVE↔ACTIVE danger-control axis); and the false-tameness reading. (Fix pass note: the tree text was not edited in this pass; if the badge wording is carried there it should take the model-specific qualifier.)

history (Petroski "form follows failure" lens)

origin. FLEX documents the high-speed angle grinder as a 1954 tool (DL 9) [H-FLEX] — a 20th-century invention, born when a compact universal motor and a right-angle bevel gearhead could put a bonded abrasive wheel in one hand. The corded tool's history is the Angle Grinder entry's (Run 186) and is carried, not re-derived.

key evolutions, each answering a failure (the cordless/brushless chapter):

• The cord → the battery (by 1985; Metabo's first in 2011). The failure answered: the tether — the cord that snags, must reach an outlet, and drags through the spark stream and the cutting line. The earliest cordless grinder found is Makita's 7.2 V 9500D (1985 parts record) [manual, relayed] [H-MAKITA9500]; Metabo's brushed W18LTX (2011) was Metabo's first [H-METABO]. Early cordless grinders were brushed and modest in power.
• The brushed motor → the brushless motor (from 2013). The failure answered: energy loss and wear. Brush friction and commutator arcing waste energy a battery can ill spare. (Run 274) Milwaukee's M18 FUEL grinder (2013) and Makita's XAG03M (2014) are the earliest brushless examples found [H-BLDATE, H-MAKITA14]; manufacturers then positioned high-output packs and brushless tools as corded replacements — attributed manufacturer claims, model- and test-specific [H-DEWALT, H-MAKITA14].
• The control board → model-specific active protections. The failure answered: kickback and the coasting wheel. Once a control board was required to run the brushless motor, manufacturers could program it, model by model, to cut power on a detected forceful stoppage and to brake the wheel rather than let it coast (DeWalt E-CLUTCH, Makita AFT, Bosch KickBack Control, Milwaukee AutoStop/RAPIDSTOP — manufacturer claims for named models, with stated response and stop times that are the makers' own) [E-DEWALT, E-AFT, E-BOSCH, E-MILW]. Bosch itself states its system does not respond to every kickback mode [manual, relayed] [E-BOSCHLIM]. And the Hewn reading (strand 3): a well-behaved, cordless tool can be treated as tame, and the battery removes the unplug cue.
• (Run 274) A second-order failure: control-electronics heat. US 10,226,849 B2 (Black & Decker Inc.; priority 14 October 2015; granted 12 March 2019), read in full by Run 274, states that driver electronics (capacitor, power switch) "undesirably increase the heat generation of the power tool," and relocates the motor-drive circuit board into the handle, away from the motor case; it also addresses contamination of the electronics [H-PAT-BL]. Petroski's chain one step further: brushed wear → brushless motor → control-electronics heat → a relocated drive board. (Evidence for one design's answer, not the whole cordless-brushless timeline.)
• Regulatory codification (IEC 62841). IEC 62841-1:2014 replaced IEC 60745-1 and brought lithium-ion battery systems into scope [H-IEC]. The current grinder part is IEC 62841-2-3:2020 with Amendment 1:2024 (and later corrigenda); national EN adoption labels and dates differ and should be confirmed for the jurisdiction. Its public scope, as the reviewer reports it, covers grinders, polishers and disc sanders up to 230 mm and excludes dedicated cut-off machines and die grinders [manual, relayed] [H-IEC]. IEC 62841-2-3 provides product-safety requirements for the covered grinder category; accessible material supports restart-prevention requirements, but electronic kickback control should not be inferred from compliance unless the exact clause and tool classification require it (clause text paywalled, not verified). The abrasive-wheel speed rule — accessory rated speed ≥ the grinder's rated no-load speed — comes from ANSI B7.1 [H-ANSI], unchanged by the move to battery.

✦ human side — the people, not just the steel

traditions & trades (who this tool belongs to). The angle grinder is one of the most widely held powered tools across the building and metal trades: fabricators, welders, boilermakers, construction and demolition crews, metalworkers, masons and tile setters, plumbers, electricians, auto-body and exhaust workers, foundry workers, and stone and metal sculptors [HS-USERS]. Fire and rescue services also use grinders as one specialist option among cutting tools; that is trained specialist use under agency procedure and scene hazard control, not a general match (see matching). The cordless form has spread the tool further into field and remote work where no outlet is at hand — roadside, rooftop, trenchside — where its own spark, dust and fall hazards travel with it.

the reputation — "the grinder will hurt you." Among tradespeople the angle grinder carries a specific, earned dread. FEIN, citing RoSPA, reports it among the most dangerous hand-held tools, with on the order of 5,400 injuries a year in the UK (secondary figure, MED) [M-STATS]; a US figure of ~25,000 injuries in a year is attributed to CPSC data via an industry summary (secondary, MED) [M-STATS]; and a much-repeated shop saying holds that the grinder hurts more people than anything else on the bench [HS-LORE]. The dread is supported by the peer-reviewed injury record (below). The Hewn reading is that the cordless form's convenience can erode that dread where it should not.

named hands & famous use cases. The tool's cultural footprint runs from metal sculpture (a primary shaping tool for steel sculptors) to fire-and-rescue cutting (specialist, above). On the dark side, the angle grinder is also a notorious forced-entry tool (bike-lock and safe attacks), a use the cordless form makes easier — named honestly, not as a match.

stories (the human texture — lower-confidence, forum-sourced; AI-collected, not Hewn testimony). The trade forums are full of grinder-injury confessions — kickback gashes, disc-shatter near-misses, the disc that "walked" up a workpiece into a forearm. r/Welding, r/metalworking, BladeForums and the hobby-metal boards treat "respect the grinder" as received wisdom, and a recurring forum line is that a machinist "has seen more accidents from angle grinders than anything else in the shop" [HS-LORE]. (Run 274) GarageJournal.com and MIG-Welding.co.uk threads carry named-poster debate on the cordless form: matt_i — "I had to cut off a fence post in a parking lot... It would have taken a generator. Perfect tool for the job."; iamrfixit — "The 60v feels just the same as using a corded tool... it can burn through a battery in about 15-20 min of use."; dr_clyde — "Grinders are very power hungry... CHEAP cordless grinders [suck]. GOOD ones are a very useful tool."; firebox40dash5 — "I had the original Makita LXT grinder and found it almost worthless... I opted for the Fuel when I went Milwaukee, and it's been great." A GarageJournal thread, "Smoked my m18 fuel grinder" (February 2022), has poster signcrafter writing "I put wheels on that should be on the bigger 7\" grinder... It went it smoked and shut off," which other posters (American Locomotive, engineer2) diagnosed as overheated control electronics or windings — a forum illustration of fitting accessories outside the tool's rating, not a verified failure analysis [HS-FORUM]. Confidence: LOWER (forum/anecdote) — held as human texture, not as proof.

✦ proof of existence (for the Library of Human Making)

earliest dated example (the tool's origin): the corded high-speed angle grinder — FLEX (Ackermann + Schmitt) DL 9, 1954, manufacturer-documented as the first high-speed angle grinder [H-FLEX]. The cordless form's earliest dated example found: Makita 7.2 V 9500D, a cordless grinder with a parts record dated 19 November 1985 [manual, relayed] [H-MAKITA9500, H-USITC] (whether it is an "angle grinder" in the narrow sense is unresolved). Metabo W18LTX, announced 11 August 2011, is Metabo's first cordless angle grinder [H-METABO]. The brushless cordless form's earliest example found: Milwaukee M18 FUEL 2780/2781, previewed June 2013 and shipping October 2013, dated by trade reports (Run 274) [H-BLDATE]; then Makita XAG03M, late 2014, by Makita's own press release [H-MAKITA14]; then DeWalt FlexVolt DCG414, announced June 2016 [H-DEWALT].

museum / collection records: none located — an honest gap.

patents (dated, with numbers):

• US 10,226,849 B2 — "Handheld grinder with brushless electric motor" — assignee Black & Decker Inc.; priority 14 October 2015; granted 12 March 2019; covers brushless drive electronics, contamination protection and relocation of the drive board away from the motor (read in full by Run 274; assignee and priority also given by the reviewer) [H-PAT-BL].
• EP 3,292,959 A1 — "Electronic braking for a power tool having a brushless motor" (grinders named; the control unit brakes the motor on a detected kickback condition and defines kickback) — details from snippet, flagged [H-PAT-EB].
• US 11,607,790 — "Kickback control methods for power tools" (a processor ceases driving the brushless motor when roll position leaves the working angle range) — details from snippet, flagged [H-PAT-KB].
• US 9,095,950 — "Motor-driven angle grinder" (granted 4 Aug 2015) [H-PAT-MG].
• US application 2018/0193972 — battery-operated grinding appliance (describes a reduction ratio of 1.5 to 3.5) [manual, relayed] [A-REDUCTION].

documentary / standards evidence: dated manufacturer press releases and trade reports anchor the descent (Makita 9500D record 1985, Metabo 2011, Milwaukee 2013, Makita 2014, DeWalt FlexVolt 2016, Makita XGT 2021) [H-MAKITA9500, H-METABO, H-BLDATE, H-MAKITA14, H-DEWALT, H-MAKITA]; the standards record — IEC 62841-1:2014 and IEC 62841-2-3:2020+AMD1:2024 (national adoptions vary), plus ANSI B7.1 for the abrasive-wheel speed rule [H-IEC, H-ANSI]; and the misuse record — two government fatality alerts (WorkSafe QLD 2016, 2021), a UK Government chainsaw-disc safety alert, an HSE-investigated circular-saw-blade fatality (BALI), and multiple peer-reviewed injury studies [M-GUARD, M-CHAIN, M-SAW, M-MED].

named gaps (honest holes):

• Earliest cordless angle grinder unresolved — the 1985 Makita 9500D record is the earliest cordless grinder found; its classification as an angle grinder was not checked, and the record was not read in this pass.
• Earliest brushless cordless grinder rests on trade reports (Run 274), not a directly retrieved Milwaukee launch record; an AEG forum claim is unconfirmed.
• No museum specimen of any cordless/brushless grinder.
• The "false tameness" reading is INFERRED, and the load-cue question (strand 3c) is untested.
• IEC 62841-2-3 clause text is paywalled — restart-prevention support and the absence of a universal kickback-control requirement rest on the reviewer's reading of public material.
• Brushless efficiency/life figures (~20–30%, ~50%) are trade-press claims — MED.
• EP 3,292,959 A1 and US 11,607,790 details are from snippets.
• Brake stop-times and kickback response times are manufacturer claims for named models, not independently measured.
• One-handed-use ~40% figure — secondary (FEIN citing NCBI); primary study not retrieved.
• Shelf-life "2-year" figure — Norton/Saint-Gobain guidance for specific resinoid wheels, not a universal rule.
• Rescue use — no rescue-agency procedure is cited; the entry gates it rather than describing it.
• XAG03M press-release date — 31 October (Run 274) vs November 2014 (the reviewer); to be re-checked.

references

kind: book | video | blog | forum | reddit | museum | patent | named_maker | archaeological | manufacturer | standard | government | peer_reviewed | trade_press. Fix pass 2026-10-16: tags marked "relayed" were added from the reviewer's 2026-07-28 source notes and were not read in this pass; only OSHA 1926.303 was re-read.

• [H-FLEX] FLEX, "70 Years of the Angle Grinder" (company history; DL 9, 1954) — manufacturer — https://www.flex-tools.com/en/company/70-years-angle-grinder (the reviewer: https://www.flex-tools.com/en-gb/company/70-years-angle-grinder) ; Wikipedia "Angle grinder" (citing Henke, Fliesen und Platten, Jan 2009) — https://en.wikipedia.org/wiki/Angle_grinder . MED-HIGH (manufacturer history claim).
• [H-MAKITA9500] Makita 9500D Cordless Grinder parts record (7.2 V; parts date 19 November 1985) — https://assets.northerntool.com/products/159/documents/manuals/1591889.pdf ; Makita Canada 9500D instruction manual — https://www.makita.ca/data/upload/owners_manuals/%289500D%29883553-949_74385_owner_English.pdf — manufacturer. Relayed from the reviewer; not read in this pass.
• [H-USITC] U.S. International Trade Commission, Certain Electric Power Tools, Battery Cartridges, and Battery Chargers (lists Makita 9500D as a cordless grinder) — government — https://www.usitc.gov/publications/337/pub2389.pdf . Relayed from the reviewer; not read in this pass.
• [H-METABO] PR Newswire, "Metabo's First Cordless Angle Grinder Features Rotating Battery Pack" (W18LTX, 11 Aug 2011, brushed, 8,000 RPM) — manufacturer press release — https://www.prnewswire.com/news-releases/metabos-first-cordless-angle-grinder-features-rotating-battery-pack-127538558.html . HIGH for a Metabo milestone (dated); does not support category priority.
• [H-MILW] Milwaukee Tool, M18 FUEL 4-1/2"/5" Grinder 2780-20 (POWERSTATE brushless; "world's first cordless grinder") — manufacturer — https://www.milwaukeetool.com/products/details/m18-fuel-4-1-2-5-grinder-paddle-switch-no-lock-tool-only/2780-20 . Manufacturer claim; the "first" wording is contradicted by [H-MAKITA9500].
• [H-BLDATE] (Run 274) ToolGuyd (12 Jun 2013 preview; 27 Oct 2014; 10 Jul 2015); masoncontractors.org press-release reprint (27 Sep 2013); Pro Tool Reviews (15 Nov 2013) — trade_press. MED (dated trade reports; no direct Milwaukee launch record).
• [H-MAKITA14] Makita press release, "New Makita 18V LXT Brushless Angle Grinder Is a True Replacement for Corded Models" (XAG03M, 2014) — manufacturer — https://makitatools.com/company/press-releases/2014/new-makita-18v-lxt-brushless-angle-grinder-is-a-true-replacement-for-corded-models . HIGH for the dated product; "corded replacement" is manufacturer positioning. (Read by Run 274; relayed by the reviewer; not read in this pass.)
• [H-DEWALT] PR Newswire, "DeWalt Unveils FlexVolt System" (June 2016) + DeWalt DCG414B/DCG418 spec pages (9,000 RPM, brushless, 60V) — manufacturer — https://www.prnewswire.com/news-releases/dewalt-unveils-flexvolt-system-300287847.html ; https://www.dewalt.com/en-us/product/dcg418x2 . HIGH (dated); performance wording is manufacturer claim.
• [H-MAKITA] Makita 40V XGT GAG01Z (2021, 8,500 RPM, AFT) — manufacturer / Home Depot — https://makitatools.com/products/details/GAG01Z ; https://www.homedepot.com/p/316616908 . MED-HIGH (manufacturer spec).
• [H-FLEXCORD] FLEX company history (own first cordless L 125 18.0-EC, 2017; first brushless 2021) — manufacturer — https://www.flex-tools.com/en/company/70-years-angle-grinder . MED-HIGH (FLEX's own milestones only).
• [A-BL] Wikipedia "Brushless DC electric motor" + ElectronicsHub BLDC working principle (commutation; sensored and sensorless control); Mafpro / Kafuwell brushless-vs-brushed (efficiency/life figures, MED); Milwaukee POWERSTATE / Makita BL motor copy — encyclopedic + trade_press + manufacturer — https://en.wikipedia.org/wiki/Brushless_DC_electric_motor ; https://www.electronicshub.org/brushless-dc-motor-bldc-motor/ ; https://mafpro.in/brushless-vs-brushed-motors-in-power-tools-whats-the-difference/ . HIGH (mechanism) / MED (figures).
• [A-CELLS] (Run 274) ToolGuyd (Apr 2021, XGT cell wiring); Contractor Supply Magazine (7 Mar 2019, Milwaukee 21700 cells); Pro Tool Reviews (Mar 2021) — trade_press. MED.
• [A-PARTS] Hoprio "Main Components of a Brushless Angle Grinder"; mikeshoppingroom angle-grinder gears — trade_press/OEM — https://www.hoprio.com/the-main-components-of-a-brushless-angle-grinder-and-how-they-work-together.html . MED. No longer cited for a gear ratio.
• [A-REDUCTION] Battery-operated grinding appliance patent application (reduction ratio 1.5 to 3.5) — patent — https://patents.justia.com/patent/20180193972 . Relayed from the reviewer; not read in this pass.
• [A-SPINDLE] Bosch GWX18V-50PCN spec ("Spindle Thread: 5/8-11 UNC") — manufacturer — https://www.boschtools.com/us/en/products/gwx18v-50pcn-06017B0610 . HIGH (5/8-11 on that model); MED (US/EU split).
• [A-GUARD] Norton Abrasives, ANSI B7.1 industry standard / grinding-wheel guards — manufacturer/standard — https://www.nortonabrasives.com/en-us/resources/expertise/ansi-b71-industry-standard-grinding-wheel-safety . HIGH.
• [A-XLOCK] Bosch X-LOCK (GWX18V-50PCN — snap mount, no flange nut/spanner) — manufacturer — https://www.boschtools.com/us/en/products/gwx18v-50pcn-06017B0610 . HIGH (that model).
• [A-VAR] Makita GAG01Z; DeWalt DCG460B (7"–9", 60V); Milwaukee 2880-20 (braking) / 2883-20 (slide) / 3672-20 (4.5–6"); switch + disc-size + platform variations — manufacturer — multiple Milwaukee/DeWalt/Makita product pages. MED-HIGH (manufacturer specs).
• [E-AFT] Makita AFT (Active Feedback-sensing Technology — maker says it shuts the motor off when the wheel is forced to a sudden stop) — manufacturer/retailer — https://makitatools.com/products/details/GAG01Z ; https://www.homedepot.com/p/314975202 . Manufacturer claim, model-specific.
• [E-BOSCH] Bosch GWX18V-50PCN — KickBack Control, Drop Control, Restart Protection, Soft-Start, X-Brake — manufacturer — https://www.boschtools.com/us/en/products/gwx18v-50pcn-06017B0610 . Manufacturer claim for that model.
• [E-BOSCHLIM] Bosch Professional, angle-grinder protection technology (forceful wheel stoppage can activate KickBack Control; twist/cant and snagging may not) — manufacturer — https://www.bosch-professional.com/gb/en/proper-use/angle-grinders/module-4/ . Relayed from the reviewer and Run 274; not read in this pass.
• [E-MILW] Milwaukee M18 FUEL Braking Grinder 2880-20 (RAPIDSTOP, ≤2 s) + Dual-Trigger 2986-20 (two-hand activation, fixed side handle, AutoStop, stated ≤1 s brake) — manufacturer — https://www.milwaukeetool.com/products/details/m18-fuel-4-1-2-5-braking-grinder-paddle-switch-no-lock/2880-20 ; https://www.milwaukeetool.com/products/details/m18-fuel-4-1-2-5-dual-trigger-braking-grinder/2986-20 . Manufacturer claims, model-specific.
• [E-DEWALT] DeWalt FlexVolt DCG418 / DCG460B — Kickback Brake + Anti-Rotation E-CLUTCH (stated to trip in <0.1 s) + No-Volt restart switch — manufacturer — https://www.dewalt.com/en-us/product/dcg460b/flexvolt-60v-max-7-9-178mm-230mm-cordless-large-angle-grinder-tool-only . Manufacturer claims, model-specific.
• [E-BRAKE] Makita electric brake (stated to stop the wheel in ≤2 s) — manufacturer/retailer — https://www.coastaltool.com/products/makita-gag01m1-40v-max-xgt-4-1-2-5-angle-grinder-kit . Manufacturer claim, model-specific.
• [E-AWS] Makita Auto-Start Wireless System (wireless start/stop of a compatible extractor; the extractor has its own power) — manufacturer — https://makitatools.com/aws . Description corrected per the reviewer; not read in this pass.
• [S-DEWALTMAN] DeWalt DCG418 instruction manual (accessory compatibility, inspection, PPE, bystanders, battery, safe operation) — manufacturer — https://assets.dewalt.com/GLOBALBOM/QU/DCG418B/1/Instruction_Manual/EN/N770107_DCG418.pdf . Relayed from the reviewer; not read in this pass.
• [S-TOOLBOX] OSHA angle-grinder use training sheet (secure the work, two-handed use, guarding, PPE, dust/fume/fire/noise hazards, ring test "as appropriate") — government — https://www.osha.gov/sites/default/files/2018-12/fy15_sh-27664-sh5_Toolbox_Angle_Grinder.pdf . Relayed from the reviewer; not read in this pass.
• [S-SILICA] OSHA 1926.1153, Respirable crystalline silica (Table 1: wet or shrouded controls and, in stated circumstances, respiratory protection for handheld-grinder tasks) — government — https://www.osha.gov/laws-regs/regulations/standardnumber/1926/1926.1153 . Relayed from the reviewer; not read in this pass.
• [S-HOTWORK] OSHA hot-work guidance (grinding as an ignition source; combustible control, hazard assessment, PPE, fire watch / hot-work procedures) — government — https://www.osha.gov/etools/oil-and-gas/general-safety/hot-work-welding . Relayed from the reviewer; not read in this pass.
• [S-ALU] OSHA interpretation on aluminum grinding, 2009-10-08 (mixed-metal dust, aluminothermic reaction, combustible dust, hot work) — government — https://www.osha.gov/laws-regs/standardinterpretations/2009-10-08 . Relayed from the reviewer; not read in this pass.
• [M-BURST] Modern Machine Shop, "Grinding Wheel Safety: Respect The Maximum Speed" (double speed → quadruple stress; ANSI/OSHA violation) — trade_press/standard — https://www.mmsonline.com/articles/grinding-wheel-safety-respect-the-maximum-speed ; Benchmark Abrasives RPM ratings. HIGH.
• [H-ANSI] ANSI B7.1 "Safety Requirements for the Use, Care, and Protection of Abrasive Wheels" (wheel rated speed ≥ spindle speed; factory test ≥110%) — standard via Norton/Buffalo Abrasives/UAMA — https://www.nortonabrasives.com/en-us/resources/expertise/ansi-b71-industry-standard-grinding-wheel-safety ; https://uama.org/safety-guide-page/ . HIGH (via secondary summaries).
• [M-OSHA] OSHA 1926.303 (abrasive wheels — guard exposure not over 180° on portable wheels (c)(3)/(c)(5); inspection and ring testing before mounting (c)(7); eye protection (c)(9); nut "tightened only enough to hold the wheel") + OSHA 1910.243 (constant-pressure switch on >2" portable grinders) — government — https://www.osha.gov/laws-regs/regulations/standardnumber/1926/1926.303 ; https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.243 . HIGH. 1926.303 (c)(3), (c)(5), (c)(7), (c)(9) re-read 2026-10-16.
• [M-1910215] OSHA 1910.215, Abrasive wheel machinery (general-industry inspection; organic-bonded wheels do not give the same clear ring as vitrified or silicate wheels) — government — https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.215 . Relayed from the reviewer; not read in this pass.
• [M-RING] OSHA 1926.303(c)(7) + Norton "How to Perform a Ring Test" (mainly applicable to vitrified wheels; may be inapplicable by size, shape or composition) + Yale EHS / Oregon DOT ring-test guides — government/manufacturer — https://www.nortonabrasives.com/en-us/resources/expertise/how-perform-ring-test-grinding-wheel . HIGH (OSHA text re-read); Norton applicability relayed from the reviewer.
• [M-AGE] Norton / Saint-Gobain, "Shelf Life of Grinding Wheels" (resinoid wheels suspect after 2 years; re-inspect/re-speed-test) + handling/storage (50–90°F, <65% RH) — manufacturer — https://www.nortonabrasives.com/en-us/resources/expertise/shelf-life-grinding-wheels . HIGH (for the wheel types it names).
• [M-GUARD] WorkSafe Queensland incident alerts — Maleny fatality (4 Feb 2016, oversized 14" disc, guards removed) + Brisbane fatality (June 2021, unguarded 9" grinder, metal shard to neck) — government — https://www.worksafe.qld.gov.au/news-and-events/alerts/incident-alerts/2021/worker-killed-by-piece-of-metal-ejected-from-unguarded-angle-grinder ; https://southburnett.com.au/news2/2016/03/15/fatality-sparks-safety-warning-about-angle-grinders/ . HIGH.
• [M-KICK] cnmeineng.com "What is Kickback? The Physics of Danger" + GarageWelding + Cornell EHS Angle Grinder Toolbox Talk — engineering/EHS — https://ehs.cornell.edu/campus-health-safety/occupational-safety/tool-and-machine-safety/angle-grinder-toolbox-talk . HIGH (mechanism).
• [M-1HAND] FEIN, "Angle Grinder Safety" (one-handed use ~40% of accidents, citing NCBI; Protago designed against it; RoSPA ranking) — manufacturer/safety body — https://fein.com/en_uk/application-tips/angle-grinder-safety-how-to-avoid-workplace-injuries/ ; weeklysafety.com portable-grinder safety. MED (secondary figures).
• [M-MED] Peer-reviewed injury literature — Head & Face Medicine 2008; Int. J. Otolaryngology 2020; Orthopedics 2021 (hand 46.4%, head 23.0%); PubMed 2018; PMC 2011 — peer_reviewed — https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2263029/ ; https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7900576/ . HIGH.
• [M-CHAIN] UK Government safety alert + Warwickshire Trading Standards — angle-grinder chainsaw-disc attachments ordered off sale — government — https://www.gov.uk/government/news/uk-safety-alert-issued-for-angle-grinder-chainsaw-disc-attachment . HIGH.
• [M-SAW] BALI / HSE — landscaper killed after a circular-saw blade was fitted to an angle grinder; NT WorkSafe alert — government/industry — https://www.bali.org.uk/news/landscaper-sentenced-following-death-of-worker/ . HIGH.
• [M-DIE] Tend Industrial Supplies, "Die Grinders vs. Angle Grinders" (higher-speed low-torque vs lower-speed high-torque; accessories not interchangeable) — trade_press — https://tendsupplies.com/blog/die-grinders-vs-angle-grinders-a-complete-guide-to-choosing-the-right-power-tool/ . MED-HIGH.
• [M-PARITY] Milwaukee M18 FUEL cut-off grinder 2686-20 (11,000 RPM no-load; same no-load figure as corded DeWalt DWE402); FEIN "same power as comparable corded grinders" — manufacturer — https://www.milwaukeetool.com/products/details/m18-brushless-4-1-2-5-cut-off-grinder-paddle-switch/2686-20 ; https://fein.com/en_uk/machines/grinding-polishing/angle-grinders/ . HIGH for the speed figures; supports same speed class only, not power, torque or duty parity; "same power" is a FEIN claim.
• [M-LIVE] Jovant Tools / Heamar cordless-grinder safety guides (battery keeps the tool live; remove the battery, don't trust the trigger lock) — manufacturer/trade — https://jovant.com/blogs/diy-tools-tips-tricks/cordless-angle-grinder-safety-tips . MED.
• [M-ANTIRESTART] FIXTEC + Jovant safety guides (restart protection prevents start if battery inserted with switch locked on) — manufacturer/trade — https://www.fixtectools.com/Avoid-Accidents-With-These-Angle-Grinder-Safety-Rules-id43514936.html . MED.
• [M-COAST] TFT Pneumatic "18 Ways Angle Grinder Accidents Happen" (wheel does not stop immediately on no-brake models) — trade_press — https://tft-pneumatic.com/blog/angle-grinder-accidents/ . MED.
• [M-SHRAPNEL] CoAction Specialty "Grinders Stats and Facts" (shattered discs as missiles) + HASpod — safety/industry — https://coactionspecialty.safetynow.com/grinders-stats-and-facts/ . MED. Its "~26% fatal" figure is no longer used (no primary dataset or denominator).
• [M-STATS] RoSPA ranking + ~5,400 UK injuries/yr (FEIN citing RoSPA) + ~25,000 US injuries/yr (CPSC, via CoAction) — safety body (secondary) — see [M-1HAND], [M-SHRAPNEL]. MED (secondary). Fatality percentages removed in the fix pass.
• [M-SIDELOAD] Norton "Safety: Cutting vs. Grinding" (cut-off wheels lack lateral strength; side-grinding damages reinforcement → breakage; guards differ by operation) — manufacturer — https://www.nortonabrasives.com/en-us/resources/expertise/safety-cutting-vs-grinding . HIGH. Replaces the unlisted [M-NOTFOR] tag.
• [M-OVERLOAD] Rynex Tools high-performance grinders (electronic overload protection cuts the motor on bind/overload) — trade_press/manufacturer — https://www.rynextools.com/blog/high-performance-angle-grinders-what-sets-them-apart . MED.
• [H-IEC] IEC 62841-1:2014 (replaced IEC 60745-1; Li-ion in scope) — https://www.iecee.org/certification/iec-standards/iec-62841-12014 ; IEC 62841-2-3:2020+AMD1:2024 (current international publication; public scope as relayed by the reviewer) — https://webstore.iec.ch/en/publication/102620 ; EN IEC 62841-2-3:2021 (one national/regional adoption) — https://standards.iteh.ai/catalog/standards/clc/f2639a9a-2e9e-4301-8b8b-36086fac65ce/en-iec-62841-2-3-2021 — standard. HIGH (existence); scope and edition relayed from the reviewer; clause text paywalled.
• [H-PAT-BL] US 10,226,849 B2, "Handheld grinder with brushless electric motor" (Black & Decker Inc.; priority 14 Oct 2015; granted 12 Mar 2019) — patent — https://patents.google.com/patent/US10226849B2/en . HIGH (read in full by Run 274; assignee and priority confirmed in the reviewer's notes).
• [H-PAT-EB] EP 3,292,959 A1, "Electronic braking for a power tool having a brushless motor" — patent — https://patents.google.com/patent/EP3292959A1/en . HIGH (existence); details from snippet.
• [H-PAT-KB] US 11,607,790, "Kickback control methods for power tools" — patent — https://image-ppubs.uspto.gov/dirsearch-public/print/downloadPdf/11607790 . MED (snippet).
• [H-PAT-MG] US 9,095,950, "Motor-driven angle grinder" (granted 4 Aug 2015) — patent — https://patents.justia.com/patent/9095950 . MED (Justia aggregator).
• [HS-USERS] Wikipedia "Angle grinder" (trades/uses); Benchmark Abrasives; Tulsa Welding School — encyclopedic/trade_press — https://en.wikipedia.org/wiki/Angle_grinder . MED-HIGH (trades).
• [HS-LORE] Allen Law Group "Infamously Dangerous Power Tools"; Canadian Hobby Metal Workers thread; BladeForums "3 Most Dangerous Accidents Using Angle Grinders" — forum/blog — https://www.kenallenlaw.com/2024/01/infamously-dangerous-power-tools-angle-grinders-chainsaws-table-saws-lathes/ . LOWER (forum/anecdote — human texture only).
• [HS-FORUM] (Run 274) GarageJournal.com threads (named posters matt_i, iamrfixit, dr_clyde, firebox40dash5; "Smoked my m18 fuel grinder", Feb 2022: signcrafter, American Locomotive, engineer2); MIG-Welding.co.uk (named poster Hood) — forum. LOWER (forum — human texture only).

✦ the genuinely-new structural reading (the entry's headline — held as interpretation)

Three braided strands, each an interpretation of the sourced facts, and — the honest part — strands 2 and 3 are two readings of one root fact (a control board sits between the hand and the cut), seen first as engineering that can reduce specific failure modes and then as the human trap that the same engineering can set.

1 — The grit-side CORDLESS DEMOCRATIZATION, the twin of Run 196's tooth-side node — battery portability now built on BOTH sides of the mechanism wall. Run 196 built the Cordless Carbide Metal-Cutting Circular Saw and read it as the bottom rung of the cool-sever price/portability ladder — democratization carried to a handheld battery format on the foreign tooth×sever lineage. This run builds its grit-side twin: the corded Angle Grinder (Run 186) carried the Bench Grinder's bonded wheel off the bench into one hand; the cordless grinder carries it off the cord entirely. So the same two-step democratization — bench → handheld → cordless — is now built on both sides of the family's central tooth-vs-grit wall: the grit branch reads Bench Grinder → Angle Grinder → cordless brushless grinder, the tooth branch reads Cold Saw → Carbide Dry-Cut Chop Saw → cordless carbide circular saw. The mounting axis (fixed→handheld→untethered) is confirmed as a property of the whole family, not of one branch. (Labelled interpretation; the twin/parallel reading is Haft's synthesis, the lineage nodes are built corpus.)

2 — The abrading family's FIRST member where ACTIVE ELECTRONICS can sit between the hand and the cut — danger control can move, model by model, from PASSIVE-and-on-the-operator toward ACTIVE-and-inside-the-tool. Every prior abrading member's danger control was passive and external to the tool's own decision-making: the guard is a shield (it deflects, it does not decide); accessory inspection is the operator's judgment before mounting [M-OSHA, M-RING]; the rated-RPM rule is a printed number the operator must read and match [M-BURST]; the two hands are the operator's body resisting a kickback that has already begun. A brushless motor cannot run without a control board, and once that board is in the circuit a manufacturer can program it to carry protections. Named examples, each a feature of the stated model, not of the family: Makita AFT, which the maker says shuts the motor off when the wheel is forced to a sudden stop (GAG01Z) [E-AFT]; Bosch KickBack Control, Drop Control, restart protection, soft start and X-Brake (GWX18V-50PCN) [E-BOSCH]; DeWalt E-CLUTCH and Kickback Brake (DCG418 / DCG460B) [E-DEWALT]; Milwaukee AutoStop and RAPIDSTOP on the Dual-Trigger 2986-20 [E-MILW]. These systems do not detect every kickback mode: Bosch states that forceful wheel stoppage can activate its KickBack Control, while twist/cant kickback and snagging may not [manual, relayed] [E-BOSCHLIM]. Stated brake times and response times are manufacturer claims for those models under their test conditions (the <0.1 s figure is DeWalt's E-CLUTCH claim; ≤1 s and ≤2 s are Milwaukee and Makita brake claims), not grinder specifications. Kickback can develop faster than a person reacts [M-KICK]; a control board is the first part of this tool that can intervene in that window, on the models that carry it. A new axis the corpus has not seen in this family: PASSIVE↔ACTIVE danger control — and this member is the family's first crossing of it. Electronic controls are mitigation, not permission: they reduce specific failure modes and do not replace guarding, workholding, two-handed control, correct body position or compatible accessories. Note: the "first member with electronics" framing is scoped to the Hewn abrading lineage as Haft has built it; prior powered tools outside this branch have carried electronic controls. (Labelled interpretation; the passive→active framing is Haft's, the specific features are manufacturer claims for named models.)

3 — The "FALSE TAMENESS" reading — a grinder with protections can be treated as tame, and it is not. Petroski's form follows failure says the electronics were added to answer the grinder's signature failures (kickback and the coasting wheel), on the models that carry them. The Hewn reading is that this success can create a new failure mode the steel never had: complacency. Two sourced facts and one open question braid into it. (a) The hazard is not tame. Cordless grinders can run accessories at the same rated speed class as corded models (for example, Milwaukee lists its M18 FUEL cut-off grinder 2686-20 at 11,000 RPM no-load, the same no-load figure as the corded DeWalt DWE402) and retain the same categories of accessory-breakage, contact and kickback hazard [M-PARITY]. Actual power, torque response, runtime, braking and overload behaviour are model-specific; equal no-load speed is not equal power. (b) The battery removes the unplug cue. A corded tool is visibly de-energized by pulling the plug; the cordless tool is live whenever the battery is on board, and the safe protocol shifts from "unplug" to the easily-skipped "remove the battery" [M-LIVE, S-DEWALTMAN]. (c) Open question, not a claim: whether brushless speed control changes the load cues (sound, feel, slowing) an operator relies on before a stall or cut-out. The original entry asserted a universal "full speed, then nothing" behaviour; no manufacturer, safety source or instrumented comparison supporting it was found, so it is deleted and recorded here as a question for testing. One-handed use is reported as implicated in a large share of angle-grinder accidents (FEIN citing NCBI: ~40%; secondary figure, underlying study not retrieved) [M-1HAND]. Honest flag: no safety body or manufacturer document found states the "cordless is falsely believed safer" framing — strand 3 is an inference, labelled as such. (Labelled interpretation; same root fact as strand 2, read from the human side.)

The reviewer's corrections (12)

• SHOULD-FIX — 1. Correct the first-cordless chronology — Exact claim: “First cordless angle grinder of any motor type: Metabo W18LTX — announced 11 August 2011.”
• BLOCKER — 2. Make active safety functions model-specific — Exact claim: The one-line identity defines the tool as a brushless grinder “whose control electronics also run an active safety suite (kickback detection, electric brake, anti-restart).”
• BLOCKER — 3. Add missing dust, fume, fire, and hot-work controls — Exact claim: The matching section broadly recommends masonry/tile cutting, rust and paint stripping, cutting metal, remote work, rooftops, trenches, and rescue scenes without a corresponding material-hazard or fire-control gate.
• BLOCKER — 4. Narrow vehicle-extrication and container-cutting matches — Exact claim: The tool “belongs to” emergency services and vehicle extrication, and cordless operation is presented as an unqualified advance at a rescue scene.
• BLOCKER — 5. Replace the universal ring-test instruction — Exact claim: “ANSI B7.1 + OSHA require rated RPM ≥ grinder RPM and a ring test before mounting”; the beginner-trap section tells the user to listen for a clear ring from an old wheel.
• BLOCKER — 6. Complete the PPE, workholding, and operating-position guidance — Exact claim: “A full face shield, not just glasses, is the standard.”
• SHOULD-FIX — 7. Correct the gear-train and motor-anatomy universals — Exact claim: The bevel gearset has a “gear ratio ~1:1 — directional change, not speed reduction,” and the generic brushless motor has “Hall-sensor position feedback.”
• SHOULD-FIX — 8. Remove no-load-RPM-as-power-parity and “no bog-down” claims — Exact claim: Equal no-load RPM is used to show that cordless power is “not tame,” wheel burst and kickback occur “exactly as a corded grinder does,” and brushless control removes the bog-down warning until abrupt shutdown.
• BLOCKER — 9. Repair the file schema and reconcile the recovery addendum — Exact claim: The recovery notice says the file restores the “full schema,” while the metadata begins after a prose notice and a separate horizontal rule; the addendum still says the base schema contains placeholders and leaves chronology gaps that it claims to close.
• SHOULD-FIX — 10. Fix standards scope and currency — Exact claim: “The current grinder-specific EN IEC 62841-2-3:2021 governs” the category and “kickback/restart protection are required for compliance.”
• MINOR — 11. Correct AWS and used-tool verification wording — Exact claim: “The grinder wirelessly powering a dust extractor,” and a used grinder’s electronic safety suite should be verified as functional “before trusting it for heavy work.”
• SHOULD-FIX — 12. Repair citations, performance figures, and access claims — Exact claim: The entry uses [M-NOTFOR], describes some secondary injury figures as OSHA-reviewed, and gives live price ranges without a dated source.