# Circular Saw

Hewn Tool Library · https://hewn.build/tools/circular-saw

Corrected: An independent reviewer read this entry and found corrections. They have been applied to the text, and the reviewer re-checked the correction that mattered most for safety and found it done; the others have not been re-checked yet. The list at the end is the record of what changed.

Cite as: "Circular Saw." Hewn Tool Library, hewn.build/tools/circular-saw. Reviewed 2026-07-28.

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## Identity

**Name:** Circular saw (also buzz saw). Family overview.
**Regional names:** Kreissäge (German); scie circulaire (French); marunoko, 丸ノコ, "round saw" (Japanese). Skilsaw is a company name used generically; not every handheld circular saw is a worm-drive saw.
**Family:** Saws, powered, rotary (continuous-disc).
**One line:** A family of machines in which a continuously rotating toothed disc does the cutting. Continuous rotation brings successive teeth into the engaged arc of the work without ever reversing the blade's direction. **Maximum cut depth is set by blade and machine geometry** (arbor, flange, guard, shoe or table, plunge mechanism), not by the blade radius alone.

**What the disc changes, stated carefully.** A pit saw or sash saw reverses at the end of every stroke: it stops, changes direction and accelerates again. A circular saw replaces that reciprocating reversal with continuous rotation. Teeth arrive at the cut in an uninterrupted sequence, which enables much higher throughput and compact powered machines. Two cautions:
- **Crosscut saws are not dead on the return.** The USDA Forest Service Crosscut Saw Manual says a bucking saw, usually run by one person, cuts on both the push and pull strokes, and that rakers remove material in either direction. Two-person sawyers alternate productive pulls. The universal claim that every earlier saw wasted its return stroke is false and is withdrawn. Some pit and sash arrangements had a cutting stroke and an idle return stroke; any such claim needs its own source for that specific mechanism, and this entry does not supply one.
- **Not every position on the disc is cutting.** Each tooth cuts only while it passes through the engaged arc of the workpiece, then travels through air for the rest of the turn.

**The disc is a family resemblance, not one tool.** The machines below share a spinning toothed disc and little else that matters for safety. They differ in what moves (saw or work), what restrains the work, where kickback goes, which guards apply, and which blades and materials are approved. Technique and safety rules in this entry are labeled by machine class. A rule written for one class is not a rule for another.

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## How NOT to Use It

*The danger section, rebuilt. Each rule is labeled by machine class. When the manual for your exact machine and blade says otherwise, the manual wins.*

### Not-for
- **Curves.** A rigid disc cannot follow a curved line; that is the [[Band Saw]], jigsaw or scroll saw job. Do not twist or steer stock to force a curve; that is how stock binds.
- **Ripping on a mitre or chop saw.** The mitre saw is for supported crosscuts. No safe way to support a rip on it. Sliding mitre saws: do not pull-cut (the blade can climb). (Run 117 sources: UW Physics Shop, U Michigan EHS, OSHA 1910.213(h) for the radial-arm; carried, not re-read this pass.)
- **Finished joinery surfaces.** The saw leaves a machined surface; fit visible or glue-critical joints with a plane or chisel afterward. (Convention; named source thin.)
- **Stock with metal, loose knots, splits or embedded stone.**
- **Any material or accessory the machine and blade makers do not approve.** See "Different machines for different materials," below.

### Different machines for different materials
Circular cutting machines exist for wood, metal, masonry and other materials, **but they are distinct systems.** A blade or disc alone does not turn a wood table saw, handheld wood saw, cold saw, abrasive cut-off machine or masonry saw into another of those. Guards, rated speed, arbor, dust or slurry control, clamping, motor sealing, electrical protection, feed method and permitted materials all differ. **Use only materials and accessories expressly approved by the machine maker and the blade maker.** Do not fit a wood blade to a metal-cutting machine or a masonry or abrasive disc to a wood saw. Some portable circular saws are made for metal with approved blades; that is a different tool, not a wood saw with the right disc.

**Cold saws.** Cold saws are dedicated, guarded and clamped metal-cutting machines. Ferrous high-speed-steel models and nonferrous carbide models use very different speeds and cutting systems: manufacturer data show ferrous HSS cold saws running at tens of RPM (Brobo SA350/400 manual, per the reviewer, not independently re-read), while the Scotchman CPO 350 NF nonferrous carbide cold saw has a single spindle speed of 3,000 RPM per its manual (confirmed in a search summary). **There is no universal cold-saw speed range, and the earlier "20 to 100 RPM" claim is withdrawn.** Use only the blade, speed, coolant or lubrication and material combination approved for that machine. Cold saws, metal-cutting circular saws and abrasive cut-off saws are not synonyms. **Recommend a separate Cold Saw entry** rather than treating it as a user-swappable circular-saw mode.

### Dangerous: misuse that injures the user

**Kickback (all classes, different paths).**
- **Table saw:** kickback throws stock toward the operator when the work pinches the blade or contacts the rising rear teeth. Kickback can accelerate stock violently toward the operator. **No speed is given here.** The earlier "over 100 mph" projectile figure is withdrawn: roughly 100 mph is a plausible tooth-tip speed for some blade and RPM combinations, not a demonstrated workpiece velocity. Per the reviewer, a UL kickback study measured much lower velocities in its simulations (about 17 to 27 ft/s in rip simulations, 26 to 80 ft/s component velocities in crosscut simulations); this pass did not re-read that figure and it is not relied on. Actual motion depends on blade, geometry, stock, contact, motor and energy transfer.
- **Handheld circular saw:** kickback drives the saw back toward the operator holding it. Support the stock so the kerf does not close; do not force the cut; keep a firm grip with both hands where fitted.
- **Mitre and radial-arm saws:** different climb and self-feed geometries. Radial-arm ripping is a notably dangerous configuration; follow the model-specific manual, including its anti-kickback devices and labels.
- **Headrigs:** guarded industrial feed systems.
- **A bind does not always mean a throw.** A saw can slow, stall, trip or kick back. The safe response is prevention, maintained control, releasing the trigger or switching off power as the manual directs, and waiting for full stop. Do not rely on a fixed physics story.

**Guards: keep them on, and treat removal as exceptional.**
- Keep the guard installed whenever the operation permits. Run equipment with guards in place and working (OSHA woodworking eTool).
- **When the exact operation requires guard removal** (OSHA's examples: rabbeting, dadoing, grooving, jointing, moulding): follow the saw manufacturer's approved setup; **retain the appropriate riving knife or splitter only where the manual permits;** use the specified alternative guarding or holding devices (OSHA: combs, featherboards, or suitable jigs for holding the stock where a standard guard cannot be used); keep hands out of the hazard zone; and **reinstall the guard before the next ordinary cut.**
- **Never treat guardless cutting as safe, and never assume training makes it safe.** Training lowers risk; it does not make an exposed blade safe. (The earlier statement that correct feed direction, riving knife and body position let a trained operator "stay safe" on guardless cuts is removed.)
- Per the CPSC 2007 to 2008 survey of table and bench saw injuries to operators (carried, [CS38]), a large share of injuries occurred with no guard present, many with the guard deliberately removed. Population, period and measure: that survey, operators, 2007 to 2008.

**Hands and body.** No reaching over or behind a spinning blade. No freehand cutting on a table saw. Do not cut pieces too small to keep hands clear; use push sticks or blocks. Stay out of the kickback line. For a handheld saw, do not stand where a kickback would carry the saw into you, and do not cut with the stock held only in your hand or on your leg.

**Energy control and health.** Disconnect power or remove the battery before changing blades or making adjustments. Eye, face and hearing protection for these machines. Dust collection and respiratory protection for MDF, coated or treated stock, and for silica-producing masonry work on a machine approved for it.

### Damaging: misuse that ruins the tool or the work
- **Overheating.** Feeding too slowly, a dull or gummed blade, a pinched kerf or poor chip clearance can cause temporary distortion, burning, loss of tension, cracked carbide or permanent warping. Take warped, bent, cracked, dull, gummed or vibrating blades out of service. OSHA 1910.213 requires removing dull, badly set, improperly tensioned, gummed or cracked saws (carried [CS-osha-s]).
- **Wrong blade for the cut or material.** Use the blade the saw and blade makers specify.
- **A blade larger than the machine's rated size.** An overspeed and instability hazard; OSHA 1910.213(a) limits blade size by frame lugs (carried).

### Beginner traps
- **Rip fence and mitre gauge together** with the offcut trapped between fence and blade (table saw). Use a clearance stop block set so the offcut cannot be trapped.
- **Standing in line with the blade.**
- **Trusting the guard as a substitute for technique.** The guard answers contact and projectiles; it is not the kickback control.
- **Not supporting long or wide stock.** Sagging stock pinches the blade.
- **Setting the handheld saw down while the blade is turning or the lower guard is not yet back.**

### Lineage misuse
- **Treating a table saw like a [[Band Saw]].** The rigid disc cannot turn.
- **Muscling a handheld saw like a hand saw.** Feed at the rate the tooth and motor accept.
- **Planning lumber from a circular mill on band-saw kerf assumptions,** or the reverse. Recovery depends on the operation; use the actual equipment's figures.

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## Correct Use, by machine class

*the workbench holds deep operation. What follows is a pre-use frame, not an operating manual. The manufacturer's instructions for the exact machine and blade override everything here.*

### What the family is for
Fast, straight, repeatable cuts on machines whose design, guidance system and installed blade suit the operation. A circular-saw machine can rip or crosscut when those three are right. **Tooth geometry and grain direction remain decisive.** Rotation does not separate the operation from grain direction; it lets a common powered arbor accept blades made for different operations.

### Pre-use checklist (all classes unless labeled)
1. **Isolate power.** Unplug the saw or remove the battery before changing the blade or adjusting depth, bevel or fence (CCOHS guidance on circular saws, via search summary; also standard in maker manuals).
2. **Guard function.** Confirm every guard moves freely and returns. **Handheld:** the retracting lower guard must work freely; do not hold or force it open; check it returns before setting the saw down (CCOHS summary).
3. **Blade.** Right type and rating for the machine and material, correct rotation direction, sharp, clean, undamaged, correctly mounted. Remove cracked, bent or vibrating blades.
4. **Stock.** Secured, supported along its length so the cut does not close on the blade, free of nails, screws and loose knots. Know what lies behind and below the cut: wiring, plumbing, benches, the floor.
5. **PPE.** Eye and face protection and hearing protection for these machines. Respiratory protection where required.
6. **Dust, fume and silica control.** Dust collection on wood machines. Extra care for MDF and coated or treated materials. Masonry and silica-producing work needs its own approved machine and controls, not a wood saw.
7. **Cord and battery.** Cord clear of the cut path; cord and battery undamaged.
8. **Approved combinations.** Use only the material and accessory combinations the machine maker and blade maker approve.

### Machine-labeled depth and technique points
- **Table saw:** CCOHS guidance sets blade projection at about 1/8 in (3 mm) above the stock. Fence or mitre gauge, not a rip fence used as a crosscut length stop that traps the offcut between fence and blade. A clearance stop block clamped to the fence, set so the offcut cannot be trapped, can reference length. No freehand cutting. Push sticks and push blocks for narrow work. The push-stick distances (CCOHS examples, about 6 in from fence to blade and 12 in stock width) are CCOHS recommendations, not a universal OSHA mandate; defer to the manual and your jurisdiction.
- **Handheld circular saw:** CCOHS guidance sets the lowest tooth at about 1/8 in (3 mm) **below** the stock, set with the saw unplugged or the battery out. Two-hand control where the saw has two handles. Do not remove the saw from the cut while the blade is turning; wait for full stop (Power Tool Institute guidance, via search summary).
- **The 1/8 in figure belongs to those two classes only.** Do not export it to mitre, radial-arm, panel, cold or sawmill machines.
- **Not exported:** a negative-hook or other tooth rule from one class to another.

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## Matching blocks, by machine (project and tool matching must not share these)

For each block: **machine, material, blade type and rating, maximum depth or capacity, guidance method, dust and control requirements, not-for.** Capacity values come from the specific machine's manual and are not filled in here.

**Handheld circular saw.** Suits: straight portable cuts, sheet breakdown, framing. Material and blade: per maker; wood blades on wood saws. Guidance: shoe against a straightedge or guide; two hands. Depth: set by machine and set about 1/8 in below the stock (CCOHS). Dust: extraction where available. Not for: curves, freehand work on unsupported stock, metal or masonry unless the saw is built and rated for it. Pairs with: [[Track Saw]], clamps, a straightedge guide. Substitutes for: jigsaw (straight cuts), hand saw.

**Track and plunge saw.** Suits: guided sheet and panel work where approved. Guidance: rail. Depth: machine-set. Not for: work beyond the rail and the saw's rated capacity. See [[Track Saw]].

**Table saw.** Suits: guided rip cuts and crosscuts within the saw's capacity using fence or mitre-gauge fixtures. Guidance: fence, mitre gauge, sleds only where the manual and a sound jig allow. Depth: about 1/8 in above stock (CCOHS). Dust: collection at the saw. Not for: curves, freehand, crosscutting against a trapping rip fence. Substitutes for: panel saw, track saw (some cuts).

**Sawmill headrig.** Industrial log conversion only. Guarded feed systems. No hobby or workshop operating advice.

**Mitre and chop saw.** Suits: supported crosscuts only. Not for: ripping; pull-cutting on sliding models.

**Radial-arm saw.** Suits: model-specific crosscut and rip controls. Not for: any use outside the manual; ripping needs the model's anti-kickback devices and labels.

**Panel saw.** Suits: supported sheet processing. Anatomy detail is thin in this entry (carried honest edge).

**Cold saw.** Dedicated clamped metal cutting only; own entry recommended; never a mode of a wood saw.

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## Anatomy, by machine class

### Blade (all classes; follow the blade maker)
**Plate, gullet, hook or rake angle, kerf, expansion slots, arbor hole.** Hook angle and tooth form are set for the operation. Use the blade specified by the saw maker and blade maker for the machine, material and cut. (The earlier statement that a negative-hook blade on a table-saw rip "makes the work climb" rested on a trade source and is withdrawn in favor of this rule.)

**Ordinary shop blades (table, handheld, mitre, radial-arm, panel).** Factory-made, tensioned, slotted, often carbide tipped. **Users do not hammer, roll or re-tension them.** Take a damaged, warped, bent, cracked, dull, gummed or vibrating blade out of service, and follow the blade maker's replacement or service instructions. Overheating can cause temporary distortion, resin burning, loss of tension, cracked carbide or permanent warping, depending on severity; "permanent destruction" is only one outcome. "Dishing" is used two ways: large saw plates are intentionally tensioned cold so they run flat at speed, and users also use the word for unwanted heat distortion. In this entry, "warped" means the unwanted condition.

### Sawmill headrig (industrial, guarded feed)
Large inserted-tooth discs (30 to 60 in typical in sources), a powered carriage, and a setting system for board thickness (carried, [CS11][CS12]). **Hammering, rolling and tensioning of large circular saw plates is specialist sawsmith practice and applies here**, not to ordinary shop blades (per Wengert, Woodweb, carried [CS18-w]). Heat can destroy tension on such plates. Headrigs run guarded industrial feed systems; no operating advice for them is given in this entry.

### Table saw
Arbor, throat plate, rip fence, mitre gauge, blade tilt, guard, riving knife or splitter, anti-kickback pawls where fitted. **A riving knife tracks blade height and tilt on designs built for it; a splitter is generally fixed relative to the table. Neither is universal across saws.** Use only what the saw maker supplies and permits.

### Handheld circular saw (sidewinder or worm drive)
Motor beside or behind the blade, shoe, retracting lower guard, depth and bevel adjustment, trigger. Kickback here drives the saw back toward the operator.

### Track and plunge saw
Handheld disc riding a guide rail; see [[Track Saw]]. The rail constrains lateral motion; kickback and blade-contact rules still apply per the maker's manual.

### Mitre and chop saw, radial-arm saw, panel saw, cold saw
Different climb, self-feed and clamping geometries. See the machine-labeled rules and matching blocks below.

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## Trades

Logging and lumber (headrig). Woodworking and cabinetmaking (table saw). Construction and framing (handheld). Sheet-goods work (panel saw, track saw). Metalworking (cold saw, a separate machine). Farm and estate (buzz saw, cordwood). Many materials are cut with circular cutting machines, but each material needs its own approved machine, not a swapped disc.

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## Lineage

### Ancestors
**[[Pit-Saw]] and [[Crosscut Saw]]** are the function ancestors: convert the log, rip and crosscut. The circular saw inherits the job and the tooth knowledge (rip teeth, crosscut teeth) and discards reciprocating motion. Internal links here are for consistency only and are not independent evidence for any mechanical claim.

**Powered sash mill.** Reciprocating, water or wind driven. Villard de Honnecourt drew a water-powered sawmill c.1235; Cornelis Corneliszoon van Uitgeest's Dutch wind-powered sawmill (1593/1597) used a crank. Corneliszoon's mill is reciprocating, not a circular blade; sources crediting the Dutch with an early circular saw are conflating the two (carried from Run 117, [CS6][CS7]).

**The disc before its first patent.** Samuel Miller's 1777 British patent (No. 1152, Southampton) describes a windmill-driven sawmill with a sliding carriage and mentions circular saws within the powered machine. Historians (Ball 1975, and DATAMP) read that wording as showing the circular blade was already known. That reading is attributed to those historians, not asserted as proof here. [CS5][CS8]

### Contemporaries
**[[Band Saw]].** The flexible-loop sibling. Circular disc: rigid, repeatable tooth geometry, wide kerf, straight cuts. Band: thinner kerf, can follow curves, more dependent on setup. The Band Saw entry records the same split from its side [CS4].
**Reciprocating powered saws** (jigsaw, sabre, reciprocating saw) are powered but stroked; "powered" and "rotary" are separate axes.

### Descendants (machine classes)
Handheld circular saw (sidewinder and worm drive; Michel 1920s, Emmons 1928 per Run 117 sources); track and plunge saw; table saw; radial-arm saw; mitre and chop saw; panel saw; sawmill headrig; and the metal-cutting circular machines such as cold saws. Cold saws and abrasive cut-off saws are separate from wood saws and from each other.

### Safety lineage: three branches, not a ladder
These controls answer different hazards. They are not one chronological sequence of better kickback fixes, and none substitutes for another.

| Branch | Hazard it addresses | Examples |
|---|---|---|
| **Kickback prevention** | Stock or saw thrown by a pinch, bind or contact with the rising rear teeth | Correct setup, fence or guidance, stock support, correct blade, riving knife or spreader or splitter where the machine is built for one, anti-kickback pawls or fingers where the machine has them, steady feed, body out of line |
| **Contact and projectile guarding** | Reaching the blade, flying chips and fragments | Upper and lower blade guards, safe hand position, push sticks and push blocks |
| **Injury mitigation after detected contact** | Severity of a blade contact that has already happened | Active injury mitigation (AIM), e.g. SawStop's flesh-detection brake |

Per the reviewer, citing CPSC's 2023 analysis: most table-saw blade-contact injuries are not related to kickback, and riving knives reduce but do not eliminate table-saw injuries. AIM does not prevent kickback. SawStop's own FAQ says that if a hand moves into the blade at very high speed, a serious injury is still possible, and its brake claim (under 5 milliseconds) describes blade stopping, not a guarantee of an intact finger [CS-sawstop].

**Petroski lens (corrected).** The circular saw's trade is not "a dead stroke exchanged for kickback." It is continuous rotary productivity bought with machine-specific control problems: exposed rotating energy, straight-line geometry, the need to guide and support the stock, and the consequences of a bind. Each safety device above answers one named hazard of those problems.

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## History
Mixed confidence by claim. Items below carry their grade.

- **Miller 1777 patent: HIGH** that the patent exists (DATAMP; Hampshire Chronicle 28 Apr 1777 via Grace's Guide, carried from Run 117, [CS5][CS19]). The "blade already known" reading is the historians', MEDIUM-HIGH.
- **Walter Taylor of Southampton (1734 to 1803).** Royal Navy blockmaker; circular saws in use at his Woodmill by the 1790s per Dickinson, Newcomen Society 1958 (carried, [CS20]). MEDIUM-HIGH.
- **Science Museum Group, three small circular saw blades from James Watt's workshop, dated 1758 to 1773 (object id co8216932).** Held at **MEDIUM-HIGH, not promoted.** The reviewer could not load the direct object page, and neither could this pass. The reviewer's check did support that the Watt workshop's provenance is intact and the contents were acquired in the 1920s [CS18]. The 1758 to 1773 date is still unconfirmed at the object record.
- **Circular saws in American mills.** Circular blades came first as edging and resaw tools, then as headrigs, from the 1840s and 1850s onward (Ledyard Sawmill exhibit, carried [CS11]). **Not supported at national scale:** the earlier line that "by the 1880s the circular headrig had displaced the sash mill across America." The Ledyard exhibit proves a dated local installation (an 1880 census entry for the site), not that generalization. The later displacement of circular headrigs by band headrigs needs a tighter source and a named geography. Treat both as open.
- **Expansion slots and inserted teeth.** The earlier "US, 1879 and 1914 forms" for expansion-slot patents is withdrawn: no patent numbers, so no proof weight. The inserted-tooth reference to E. C. Orr US 1,752,541 is carried from Run 117 and not re-checked this pass.
- **Handheld saws.** Edmond Michel's worm-drive saw (patent January 1924, per Run 117 sources) and Art Emmons's 1928 sidewinder. **The primary patent numbers for Michel and Emmons remain open gaps.** MEDIUM.
- **Steve Gass and SawStop.** Gass's finger-detection demo (2000) and the industry dispute are carried from Run 117 ([CS27], Inc. 2005). MEDIUM-HIGH.

### Band headrigs and circular headrigs: a conditional comparison
The USDA Forest Service band-versus-circular research (treesearch/230) supports the direction, not universal numbers: **band headrigs generally use a thinner kerf and can improve recovery**, especially where there are many headrig cuts and higher-value yield justifies their higher capital and maintenance cost. Per the reviewer's note on that source, band headrigs can cost three to six times as much, and circular headrigs may remain economical for low-value hardwood products or relatively few headrig cuts. Recovery depends on log size and quality, product mix, sawing pattern, edging and trimming, scanner and operator decisions, and equipment. **The earlier kerf and recovery percentages (about 21% against 12% of the log, and 50% against 57% recovery) are withdrawn as universal figures.** Any number must be tied to a named study, species, log mix, equipment and metric; none is offered here. Kerf for ordinary shop blades is set by the blade maker's specification for that blade.

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## Human Side

**Samuel Miller and Walter Taylor.** The two Southampton figures at the English origin. Neither is "the inventor"; the disc was already in the trade and these men powered it and used it at scale.

**Tabitha Babbitt (1779 to 1853), Harvard Shaker community.** The popular story says she invented the circular sawmill blade around 1810 to 1813 and never patented it. Corrected position: **Babbitt cannot be credited as the first inventor of the circular-saw form, because documented British evidence predates her (Miller 1777; the older blades above).** Whether she independently devised, adapted or popularized a larger American sawmill form is **disputed and poorly documented.** The Mills Archive Trust page treats the story as contested and asks for further evidence; it is not proof of the lore or of a total debunk [CS31]. The Shaker Museum's "most likely apocryphal" comment and the Mount Lebanon 1793 alternative are carried from Run 117 (Snopes [CS32]). Confidence on what she did or did not contribute: LOW.

**Edmond Michel and Art Emmons.** Worm-drive versus sidewinder, regional framing culture (per Run 117 trade sources, MEDIUM).

**Sawmill crews and women in the mills.** Head sawyer, off-bearer, setter; WWII "Pauline Bunyans" documented by the Forest History Society (carried, [CS37], HIGH). Sawmilling has a serious injury rate well above general manufacturing per WorkSafeBC (carried, [CS36]); OSHA's sawmill rules require a shield for head-saw operators (carried, [CS35]).

**Japanese tradition: a search result, not a finding.** This pass found strong sources for Japanese hand-saw traditions (pull-stroke saws) but did not establish a distinct preindustrial Japanese circular-saw lineage. The modern Japanese history of the marunoko (丸ノコ) is an open research edge. Absence from the sources searched is not proof of absence.

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## Proof of Existence

- **Science Museum Group, Watt-workshop circular blades (co8216932), dated 1758 to 1773:** the cited object lead. Provenance of the workshop collection is supported; **the object record could not be loaded, so the date stays at MEDIUM-HIGH** and is not used as proof of anything stronger.
- **Samuel Miller, British Patent 1152 (1777):** patent exists; reading of its wording is the historians'.
- **Smithsonian NMAH circular saw (acc. 1996.0324.12, nmah_1428277):** catalogued, no manufacture date (1996 is the accession year); carried, not re-checked.
- **Ledyard Sawmill, Connecticut:** a dated local installation (1880 census record for the site); not evidence for national chronology.
- **Michel and Emmons patents:** primary numbers not recovered. Open gap.
- **SawStop patents, USITC 2016:** carried from Run 117, not re-checked this pass.

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## References

**Read or confirmed (by search summary) in this pass**
- [CS-osha-etool] OSHA, Woodworking eTool, Kickbacks: https://www.osha.gov/etools/woodworking/machine-hazards/kickbacks (alternative combs, featherboards or jigs when a guard cannot be used; spreaders and anti-kickback fingers; push sticks). Search summary only; page not fetched.
- [CS-osha-1910] OSHA 29 CFR 1910.213 Woodworking machinery requirements: https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.213 (listed in results; combs or jigs when a standard guard cannot be used).
- [CS-ccohs-hand] CCOHS, Powered Hand Tools, Saws, Circular: https://www.ccohs.ca/oshanswers/safety_haz/power_tools/saw_circ.html (lower guard, 1/8 in below, disconnect before blade change). Search summary only.
- [CS-ccohs-tbl] CCOHS, Woodworking Machines, Table Saws: https://www.ccohs.ca/oshanswers/safety_haz/woodwork/tbl_saw.html (blade projection, fence, push-stick examples). Per the reviewer; not re-read.
- [CS-pti] Power Tool Institute, Circular Saws: https://www.powertoolinstitute.com/wp-content/uploads/2025/10/PTI_Circular-Saws.pdf (lower guard, support panels, wait for full stop). Search summary only.
- [CS-cpsc2023] CPSC, 2023 supplemental NPR, Federal Register 2023-23898: https://www.federalregister.gov/documents/2023/11/01/2023-23898/safety-standard-addressing-blade-contact-injuries-on-table-saws (30,000 injuries in 2021; riving knife and guard limits). Search summary only.
- [CS-cpsc-withdraw] CPSC news release, Aug 20, 2025, withdrawal: https://www.cpsc.gov/Newsroom/News-Releases/2025/CPSC-Withdraws-Rules-That-Are-Outdated-Fail-to-Advance-Safety-New-Leadership-Focuses-on-Hazards-That-Pose-Real-Risks (per the reviewer).
- [CS38] CPSC, Survey of Injuries Involving Stationary Saws: Table and Bench Saws, 2007 to 2008: https://www.cpsc.gov/s3fs-public/statsaws.pdf (85.7% along the stock; 40.5% kicked back or jumped; guard-presence data). Figures carried from Run 117 and confirmed by the reviewer.
- [CS-fs-crosscut] USDA Forest Service, Crosscut Saw Manual: https://www.fs.usda.gov/t-d/pubs/pdfpubs/pdf77712508/pdf77712508dpi72.pdf and the reviewer's cited chapters (pdf04232822dpi72pt04.pdf, pt05.pdf). Both-strokes statement confirmed by search summary.
- [CS-sawstop] SawStop FAQ: https://www.sawstop.com/why-sawstop/faqs (serious injury possible at very high hand speed; stop under 5 ms). Search summary.
- [CS-scotchman] Scotchman CPO 350 NF operator manual (3,000 RPM carbide nonferrous): https://info.scotchman.com/hubfs/Operator%20MANUALS/Saw%20Manuals/CPO%20350%20NF%205HP%20(Non%20ferrous%20manual,%20PK%20&%20PKPD)%20Operator%20Manual.pdf
- [CS-brobo] Brobo SA350/400 Cold Saw manual: https://brobo.com.au/wp-content/uploads/2024/02/02-SA350D-SA400B-Cold-Saw-Product-Manual.pdf (per the reviewer; not re-read).
- [CS-ul] UL, Table Saw Hazard Study on Finger Injuries Due to Blade Contact (2014): https://code-authorities.ul.com/wp-content/uploads/sites/40/2015/02/UL_WhitePapers_Tablesaw_V11.pdf (per the reviewer for the velocity ranges; this pass only confirmed the study's subject).
- [CS16] USDA Forest Service, Band vs. Circular Sawmills: https://research.fs.usda.gov/treesearch/230 (qualitative direction; per the reviewer's note for cost and applicability).

**Carried from Run 117, not re-checked this pass** (history and context, graded above): [CS4] [[Band Saw]]; [CS5] DATAMP Miller 1777 https://datamp.org/patents/search/advance.php?pn=177701152&id=57322; [CS6] Wikipedia, Cornelis Corneliszoon van Uitgeest; [CS7] Norman Ball, "Circular Saws and the History of Technology," Bulletin of the Association for Preservation Technology 7(3), 1975; [CS8] Wikipedia, "Circular saw"; [CS11] Ledyard Sawmill, "Circular Sawmill" exhibit; [CS12] Lunstrum, USDA Forest Products Lab, "Circular Sawmills and Their Efficient Operation"; [CS18] Science Museum Group object co8216932 and the SMG Journal article "Watt's workshop: craft and philosophy in the Science Museum" https://journal.sciencemuseum.ac.uk/article/watts-workshop/; [CS18-w] Wengert, "Hammering and Rolling Large Saw Blades," Woodweb; [CS19] Hampshire Chronicle 28 April 1777 via Grace's Guide; [CS20] H. W. Dickinson, Trans. Newcomen Society XXIX (1958); [CS27] Inc. (July 2005), Gass profile; [CS31] Mills Archive Trust, "Tabitha Babbitt (1779 to 1853)" https://millsarchive.org/2020/07/02/tabitha-babbitt-1779-1853/; [CS32] Snopes on Babbitt; [CS35] OSHA Sawmills eTool, Head Saw; [CS36] WorkSafeBC sawmills; [CS37] Forest History Society, "Pauline Bunyans and WWII Victory Lumber"; [CS-osha-s] OSHA 1910.213(s).

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## Injury statistics (denominator, period and outcome each time)

- **CPSC 2023 supplemental proposal (Federal Register 2023-23898):** an estimated 30,000 **table-saw blade-contact injuries treated in emergency departments in 2021** (a search summary of that document gives a 95% confidence interval of 24,100 to 35,900). That figure is table-saw blade-contact injuries only. It is **not** all circular-saw injuries, not all woodworking injuries, and not evidence that the table saw is the "single largest source of serious woodworking injury." The 2017 special study estimated 26,500 such injuries including 2,800 amputations (per the reviewer).
- **CPSC, 2007 to 2008 survey of injuries involving stationary saws (table and bench saws), operators only:** 85.7% of surveyed injuries occurred while cutting along the stock (ripping), and stock kicked back or jumped in 40.5% of cases. These are percentages of that surveyed set in that period, not current annual proportions of all blade-contact injuries.
- **Do not apply table-saw statistics to the handheld, mitre or other classes.**
- **Policy status:** on August 20, 2025 CPSC announced withdrawal of the pending federal table-saw blade-contact rulemaking (per the reviewer's source note, CPSC news release). That is withdrawal of the rulemaking, not a finding that AIM lacks safety value. No federal mandatory AIM rule resulted.

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