Pin Router

identity

Name: Pin Router. Also: overarm pin router, overhead router, pattern router, template router (production-floor usage; distinct from the modern retail "router template guide" accessory for hand routers).
Family: machine tools → production template-routing machines and setups.
Regional/alternate names: "inverted pin router" for the below-table-spindle variant (see Variations); "contour profiler" appears on at least one period patent title [PR8].
Defining operation (first): a cutter aligned to a guide pin, which follows a template through manual relative motion between fixture and machine.
Primary production forms: dedicated overhead and inverted C-frame machines (a rigid casting with a high-speed router spindle above or below a worktable and a fixed guide pin at the cutter's axis).
Other forms, listed separately and not equivalent in capacity or safety: benchtop units, radial-arm-saw attachments (US 4,397,342), a drill-press-supported platform (US 4,779,327A), a Lee Valley pin-router patent (US 6,289,952) and shop-made arrangements. They may be pin-routing setups without sharing the industrial C-frame architecture.
One-line: A template-following routing machine or setup: the operator moves a fixture holding the work and a template against a guide pin while the cutter duplicates the template path. Dedicated production machines are C-frame, overhead or inverted. The cutter is high-speed, the point of operation is hazardous, and guarding and a positively held fixture are required (see How NOT to Use It).

how NOT to use it (the heaviest section)

Controls come before technique. A pin router is a high-speed, hand-fed router. The cutter, the point of operation and the fixture all carry hazards, and no technique ("keep both hands on the fixture") is an engineering control. The manufacturer's manual for the exact machine, and the workplace's rules, control; this section is the general frame.

weak fit (economics; separated from the dangerous items)

• A one-off whose template would cost more than the part (see Matching).
• True multi-angle 3D carving.

dangerous (injures the user or a bystander)

Primary control: point-of-operation guarding. OSHA 29 CFR 1910.213(m)(1), read this pass, requires the cutting heads of hand-fed shapers and similar machines not automatically fed to be enclosed with a cage or adjustable guard that keeps the operator's hand away from the cutting edge; (r)(4) says the machines named in the standard are not an exclusion and other woodworking machines still need suitable guards and exhaust hoods to minimize point-of-operation hazards. OSHA's woodworking guide (publication 3157) tells operators to "Enclose the tool with an adjustable tool guard" for routers, and warns that with adjustable guards "Hands may enter danger area" and protection "may not be complete at all times." So: use the machine's suitable adjustable or cage guard, or a manufacturer-approved equivalent, set for the actual stock and fixture, and do not operate a vintage or improvised machine until a competent assessment has established an effective guard and dust hood.

Projected tool and cutter contact.

• A documented fatality, federally investigated. NIOSH FACE Report 95MA020: on June 21, 1995, a 32-year-old Massachusetts woodworker was fatally injured when a steel tool knife was ejected from an overhead pin router he had just started. The report found the router most likely set to 18,000 RPM when employees were told to run the job at 9,000 RPM; the tool holder had no stamped maximum speed (its 10,000 RPM limit was known only by word of mouth); the knives were held by set-screw friction not angled to resist centrifugal force; the machine had only a Plexiglas dust shield, which the knife passed through; and the employer had no written safety rules for the task. (This replaces the original entry's "20,000 RPM" and "25 feet" details, which this read did not match.) NIOSH recommended that employers "ensure that tooling for woodworking machines is used on the machinery intended by the tool designers," that machines be "adequately equipped with tool guards wherever possible," that tool manufacturers label tooling with maximum permissible spindle speeds, and that employers keep a safety program with hazard analysis and training.
• The lesson is broader than slow-machine tooling. OSHA 3157: "Projection of tools can severely injure or kill router operators," where tools are poorly fastened in the holder, the wrong tool is used, or the speed is too high. Require tools and holders specifically rated for the machine, spindle speed, rotation, material and operation, labeled with maximum permissible spindle speed; correct collet engagement and torque; inspection for damage before each use; balanced cutter assemblies; and a guard against both contact and projected fragments. Collets and cutters must be inspected, kept firmly secured, and replaced if damaged (OSHA 1910.213(s)(2): "All knives and cutting heads of woodworking machines shall be kept sharp, properly adjusted, and firmly secured").

Fixture control, positive workholding and kickback. A fixture can slip, rotate, kick back, expose the cutter, or draw hands toward the point of operation. OSHA 3157 identifies "poorly fixing the stock to the template" and feeding "too abruptly or in the wrong direction" as causes of kickback. Required controls: positive attachment of work to template; a fixture sized to keep a safe separation; purpose-built handles or hold-downs, positioned outside the danger and projection zones; correct feed direction; controlled engagement; and a guard. Never rely on hand grip alone, and never put hands in the cutter's projected path.

Stopping, isolation and access.

• Know the stop and emergency-stop controls and keep them within reach; remain present while the machine runs.
• Reaction force and coast-down are separate hazards with separate controls. Rigid fixturing, handles and controlled feed address cutting forces. A spindle brake addresses stopping and coast-down. A brake does not control kickback or fixture torque during cutting. OSHA 3157 recommends equipping routers with "a spindle braking system that gradually engages." Some current models have a brake and one does not, so verify the model. Wait for complete stop before any access.
• Do not reach into the cutting zone, clear scrap, or clear chips with hands or compressed air while the machine is energized or coasting.
• Isolate electrical power and stored pneumatic energy before tool changes, adjustments, clearing jams or maintenance [manual, relayed].
• Protect foot controls against accidental actuation. Supervise inexperienced operators.

Dust, noise, eyes, clothing. Use effective dust extraction and an exhaust hood (OSHA 1910.213 requires suitable exhaust hoods); respiratory controls appropriate to the material and exposure; eye and face protection; hearing protection; secured hair and clothing; non-slip housekeeping [manual, relayed].

damaging (ruins the tool or the work)

• Reusing tooling rated for a different, slower machine. The NIOSH finding above. Hardware built for one machine class can fail when carried onto a faster one.
• A full-depth cut in one pass. US 4,397,342: "it is preferable to make multiple passes" [PR10].

beginner-trap (mistakes that look fine until they aren't)

• Treating the pin and cutter as always the same diameter. The common same-diameter case gives a 1:1 relationship, but pin contact radius, cutter geometry, side followed and intended feature set the real offset. Carrying a bushing-offset habit onto a pin router, or a same-diameter assumption onto a different pin and cutter set, can produce a wrongly sized template. Verify against the machine, cutter, pin and fixture plan. For comparison, common guide-bushing setups on a hand router use an outside guide diameter larger than the cutter and therefore need an offset calculated from the actual bushing and cutter [PR31][PR32].
• Skipping the depth-turret sequence. Multiple shallow passes are the designed procedure.

lineage-misuse (treating it like its relatives)

• Treating it like a bushing-guided router table. The two tools look similar and use different guide relationships (see above).
• Treating it like a CNC router. A pin router has no automatic or programmed path control; the operator moves the fixture by hand the whole time. Someone trained on "load the file, press start" will find nothing happens without a hand on the fixture, and must not carry automatic-cycle habits onto a hand-fed machine.
• Reusing tooling from a slower machine class. The NIOSH case.

correct use

What it's good at: repeatable, hand-guided production of identical 2D/2.5D parts from a physical template, such as outside profiles, plunge cuts and grooves, inlay recesses, and mortises, tenons and rabbets via a jig. The actual capability depends on fixture design, plunging motion, cutter profile, table tilt, access and re-fixturing. Its reason for existing is repetition: a shop that needs the same part many times.

How to use it well (short version):

• Build the template and fixture first, and treat them as part of the safety system. Size the fixture to keep hands outside the cutter's danger and projection zones, attach the work to the template positively, and add purpose-built handles or hold-downs. Never rely on hand grip alone or place hands in the cutter's projected path.
• Verify the geometry. Confirm the pin, cutter, side followed and intended feature against the machine and fixture plan before cutting (see Anatomy).
• Set the guard. Use the machine's adjustable or cage guard (or the manufacturer-approved equivalent), set for the actual stock and fixture.
• Use the depth turret and make multiple passes. The patent text prefers multiple passes to a single full-depth cut [PR10].
• Feed in the correct direction with controlled engagement. Feed the fixture so the cutter is not drawn in or the stock thrown back; OSHA 3157 lists feeding "too abruptly or in the wrong direction" and poorly fixing the stock to the template as causes of kickback.
• Work with the machine manual, the exact tool's rating, and your workplace's rules in hand. the workbench holds the deeper technique; this is the short version.

matching (the workbench's first read)

does: follows a physical template to duplicate a 2D/2.5D shape into stock; plunge-cuts, grooves and bores for inlay; cuts mortises, tenons and rabbets via a jig; produces repeated parts without CAD/CAM programming. The normal same-diameter pin and cutter case gives a 1:1 template relationship, but the actual offset must be verified for the setup.

suits: repeated profiles, cavities, grooves, bores, mortises, rabbets and template-defined furniture or instrument components (guitar bodies and necks, inlay recesses, control cavities); fast secondary operations on parts already processed on a CNC router; and a one-off where the template earns its time (see below).

conditional matches (depend on fixture value, manufacturer capacity, cutter access, guarding and workholding): one-offs, angled work, deep cuts, small parts, and materials beyond wood.

kit-fit:

• Pairs with: a purpose-built template and fixture; positive clamps or vacuum hold-down with adequate area and reserve; handles; the manufacturer's guard and dust hood; extraction; rated cutters and holders; and the electrical and pneumatic service the model requires.
• Complements: a CNC router, not only competes with it (Onsrud markets inverted routers for secondary operations after CNC processing). Match on setup time, geometry, production quantity, secondary-operation needs, available fixtures, guarding and operator skill.
• Substitutes for: freehand template routing with a handheld Router where a fixture, guard and rated machine are available, noting that a machine with both hands on a fixture is still not hands-free of risk.
• Cannot replace: a CNC router for complex 3D or relief geometry, for automatically controlled repeat cycles, or for jobs with no physical template where building one costs more than the part is worth. (The original wording about "unattended repeat runs" is withdrawn. Unattended operation of any CNC router is a machine- and cell-specific condition that requires engineered safeguards, monitoring and the manufacturer's authorization, and this entry does not treat it as an ordinary capability.)

weak fit (economics, not a prohibition):

• A one-off. Weak when the template and fixture take longer than the benefit; a good match when the geometry, accuracy, safety or likely repetition justifies the template. A named practitioner reports finishing a single custom part before CNC programming would be ready [PR17].
• True multi-angle 3D carving. A pin router follows a 2D template edge at a fixed cutter orientation and cannot reach undercuts or compound-angle geometry the way a multi-axis machine can.

unsafe or prohibited (see How NOT to Use It): operation without a guard, without positive workholding and a hands-away fixture, with tooling not rated for the machine and speed, or on vintage or improvised equipment that has not been competently assessed.

access: not a beginner's first machine, and not something a typical hobbyist-scale Hewn user is likely to own. New industrial units were listed at $13,300–$14,400 for the Cantek SR750 [PR21] (July 2026, USD, freight extra). The used market was recorded at roughly $2,500 (a C.R. Onsrud inverted unit, sold) to $4,550, and $2,806 for a comparable overarm unit [PR22][PR23]; sold listings are examples, not a market range. Weights and power vary by model: Onsrud's 500 VS lists 420 lb and 120 V single phase; its 750 SS lists 1,100 lb and 3 phase, single phase optional. Check floor loading, voltage and phase, compressed air, extraction, guarding, transport and service for the exact machine. Vintage or improvised equipment should not be recommended until a competent inspection has established electrical safety, spindle condition, braking, guarding, controls, extraction and fixture safety. The harder skill is building an accurate and safe template and fixture; a named active user says "adjusting the turret gets easier the more you do it" [PR16].

revival: a real but narrow case: an ongoing (2019–present) forum thread in which a working professional luthier keeps and uses two pin routers acquired from an estate rather than converting to CNC [PR16]. The practitioner's stated reason is that a single custom part can be finished before CNC programming is ready. This reads as a still-working tool with a narrow active niche, not a hobbyist rediscovery movement.

anatomy

• C-frame (dedicated machines) — a large rigid casting; the spindle mounts on the upper arm, the table sits below [PR16]. Benchtop units and attachments differ.
• Spindle — holds the router bit and runs 10,000–22,000+ RPM (two-speed on production machines) [PR16][PR11]. Tools and holders must be rated for the machine's spindle speed (see How NOT to Use It).
• Guide pin — a steel pin fixed in line with the cutter; interchangeable pin sets are normal. Onsrud's current page (read this pass) lists guide pins at 1/4″, 5/16″, 3/8″ and 1/2″ and collets at 1/4″, 3/8″ and 1/2″, so available pin and cutter sets are not a one-to-one identity. A retractable lever drops the pin below the table when not in use [PR16].
• The pin-to-bit relationship — verify, do not assume. In the common same-diameter case, the template boundary relates 1:1 to the cut. The actual template-to-cut offset is determined by the guide-pin contact radius, the cutter geometry, which side of the template is followed, and the intended cut. Different pin and cutter relationships can intentionally change the offset. Verify against the machine, cutter, pin and fixture plan before cutting.
• Depth turret — a rotating turret of (commonly three) adjustable stops for stepping through successive depth passes by foot pedal [PR16][PR20].
• Foot pedal actuation — raises or lowers the spindle (or on some older machines the table) so both hands can stay on the fixture; pneumatic on modern machines, mechanical linkage on older ones [PR16][PR20]. A foot control must be protected against accidental actuation.
• Table — cast iron, commonly tilting to 45°, with a hand-crank elevating knee and a T-slotted or fenced surface [PR16].
• Template/fixture — a shop-built jig that is part of the safety system as well as the geometry: the template carries the pin; the work is positively attached; handles or hold-downs keep hands outside the danger zone (see How NOT to Use It).
• Guard and dust hood — an adjustable or cage guard and an exhaust hood on the point of operation are part of the machine, not accessories (see How NOT to Use It). The vendor's guard and hood are the manufacturer's to specify.
• Brake and controls — some models have an automatic spindle brake and some do not; Onsrud's current page lists an automatic brake on the 900 VS/VSX and 750 SS and none on the 500 VS (read this pass). Stop and emergency-stop controls and their placement are model-specific.

variations (living)

Prices and listings below were recorded in Run 385 (July 2026), USD, and were not re-checked in this pass.

• Overhead/overarm pin router — the classic production configuration, spindle above the table, template typically below the workpiece against the pin. Heavier and more powerful [PR16]. NIOSH FACE 95MA020 records a fatality on a machine of this type (see How NOT to Use It).
• Inverted pin router — spindle below the table (workpiece face-down), guide pin above on a lighter C-frame arm. C.R. Onsrud's signature product since 1976. A named practitioner's own judgment: "the inverted configuration is a little better for small shops and one-off jobs. The overhead machines are better for heavy production" [PR16]. The cutter still reaches the point of operation and needs the manufacturer's guard.
• Current models, as examples and not a range. From Onsrud's current page (read this pass): the 500 VS lists 420 lb shipping weight and 120 V single phase; the 750 SS lists 1,100 lb and 3 phase (single phase optional). The Cantek SR750 (7.5 HP, two-speed 10,000/20,000 RPM, 29.5″ throat, pneumatic foot-pedal actuation, 3-position depth turret, table tilts to 45°) was listed new through at least eight US distributors at $13,300–$14,400, with freight of roughly $1,150–$1,300 listed separately [PR20][PR21]. Dealer inventory, freight, options, currency and sale status change quickly. Ownership also depends on floor loading, voltage and phase, compressed air, extraction, guarding, transport and service.
• Benchtop/light-duty machines — smaller tabletop units existed (e.g., the "Router-Mate"); a Porter-Cable "612" overarm pin router is referenced by title in a forum and could not be confirmed [PR16] [flag].
• Attachments and conversions, listed separately. Radial-arm-saw pin-router mounts (US 4,397,342), a drill-press-supported platform (US 4,779,327A), and the Fine Woodworking drill-press tip below. They are not equivalent in capacity or safety to a purpose-built machine.
• The drill-press tip — what it is, read this pass. David Jeffrey's Fine Woodworking tip [PR18] uses the drill press only to carry a stationary guide pin and to set height: the pin is "a short length of drill rod or an inverted drill bit" held in the chuck, the quill is lowered and locked, and a router table is clamped to the drill press table with the router bit centered beneath the pin. The cutter is a router bit turned by a router in the router table, not a router bit in the drill-press chuck. The article gives no guard, workholding or speed details. This entry does not publish a procedure from it. Even in the arrangement as described, a separately rated router, secure mounting, a guard, a hold-down, compatible tooling and speeds, and the router's manual all still apply. Onsrud's tooling guidance, as relayed by the reviewer, says not to operate router tools in drill presses or portable drills [manual, relayed]; the arrangement above is not that, but a reader must not improvise one from a summary. The original entry called this a "zero-cost" access path. That is withdrawn: it ignores the router, the compatible tooling, the fixture, the guard and the dust controls.

trades

• Furniture and cabinet production — the tool's largest reported home.
• Lutherie/instrument-making — the best-documented thread: Fender's 1960s floor (practitioner account), Rick Kelly at Carmine Street Guitars, Gary Nava's improvised build, and named luthiers still using the machine.
• Sign-making and pattern-making — template-based duplication referenced in trade-forum discussion without a named shop.

lineage

Antecedents:

• Hand-guided template routing — the diffuse shop practice of tracing a physical pattern by hand while cutting a duplicate; no single named inventor or dated origin was found.
• The spindle shaper/moulder — a vertical rotating cutter with stock fed past it, in industrial use from the mid-19th century. (Corrected, Run 386: this entry originally named the spindle shaper as a plausible mechanical forerunner on one tertiary, AI-synthesized source [PR4]. Haft read that source's actual 1994 Australian Wood Review article and found a chronological timeline of unconnected items 59 years apart, with no stated succession. Downgraded to: shares a functional category — stationary, vertical-spindle, rotating-cutter wood-shaping machine — with no documented mechanical succession found.)
• The electric router itself (see Router for the Kelley/Carter lineage, not re-litigated here) — the pin router pairs the same cutting principle with a guide pin and a production-grade frame.
• Adjustable overarm woodworking machines. US 1,528,536 (Raymond DeWalt, "Woodworking machinery," 1923/1925) is an adjustable overarm universal woodworking machine. Its text and claims do not establish a guide-pin or template-following mechanism, and it appears here only as a patent cited within US 4,397,342. It is not pin-router lineage and is not offered as proof of any date for the tool.

Relationship to CNC routing (convergence, not descent):

• Pin routing and CNC routing share the job of reproducing a repeated 2D or 2.5D path in stock. Practitioners report CNC displaced much pin-router work [PR16][PR17]. Both fields grew beside numerical-control machine-tool development; see the structural thesis above.
• C.R. Onsrud's current page markets its inverted routers for "secondary operations after processing on one of our heavy-duty CNC routers" (read this pass), so the two are also sold as complements.
• Contemporaries: Router Table (fence-fed, bushing-guided, no fixed-pin template system) and Router (hand-held; same cutting principle, not the fixed-pin production architecture).

history

An Onsrud company milestone, not the origin of the tool class. VintageMachinery.org's archival page says: "Onsrud Machine Works, Inc. was founded in 1915 in Niles, IL. They made woodworking machinery, especially pin routers, and high speed steel cutters for wood" [PR1]. That supports a company founded in 1915 that made pin routers among other machinery. It does not show that the company was founded specifically for pin routers, or that 1915 is the origin of the tool. The pin router's own origin remains unresolved here; a dated patent, catalogue, advertisement or trade source naming the mechanism would be needed. The same archive's assigned-patents index lists Onsrud patents from 1928 ("Woodworking machine," Oscar Onsrud) through 1935, 1943, 1952 and 1960 [PR2]; US 1,685,572 is a 1928 woodworking machine emphasizing work clamping and interlocked cutter control, which does not resolve the 1915 spindle claim. Onsrud Machine Works was bought by Danly Machine Corp. in 1968; its woodworking line was sold to employees in the early 1980s and renamed Onsrud Machine Corp. [PR1].

The 1912/1915 spindle story, stated narrowly. C.R. Onsrud's current company page says: "In 1915, Oscar Onsrud and his son, Rudolph, invented and patented the first air powered, high-speed spindle" (read this pass). This is company self-history. No patent number or filing date for it was found, and the 1928 patent trail cannot substantiate a 1915 invention. "First," "invented" and "patented" are separate claims; this entry attributes the sentence to the company and goes no further. A tertiary, AI-synthesized source [PR4] gives 1912 and the product name "Ons-Rooter"; it is flagged and unverified.

A weaker, unverifiable origin claim, deliberately not asserted as fact. A forum thread on OWWM.org reportedly claims a "Boult" patent from 1869 and a J.A. Fay & Co. advertisement from 1882 showing an early pin router [PR5]. The thread was unreachable and no independent record was found. It rests on a single unverified forum source and is not carried into the timeline [flag].

The patent trail, with what each kind of document can and cannot show.

• Utility patents (mechanism evidence). US 2,592,187 (1952), "Automatic guide pin for routing machines," Karl Rohrer, assigned via Onsrud [PR7]. US 4,397,342 (filed 1981, granted 1983), "Pin-router mounting device and method," Joe E. North — adapts a pin router to a home-shop radial-arm saw and states "it is preferable to make multiple passes" rather than cutting through in one pass [PR10]. US 4,779,327A (filed 1987, granted 1988), "Drill press supported platform for pin router," Laddie J. Vander Maas — states the spindle runs "at 22,000 rpm or more" producing "a substantial reaction twisting force which must be counterbalanced" [PR11]. US 4,630,656, "Router Attachment," describes an equivalent-diameter pin and cutter for that disclosed attachment only [manual, relayed].
• Design patents (appearance evidence only). US D187,715 and D188,088 (both 1960), "Contour-profiler machine" and "Router machine," Charles R. Onsrud and Robert Louis Deschamps [PR8][PR9]. Design patents protect ornamental appearance. They are dated evidence of machine appearance and product identity, and do not establish an operating mechanism or technical novelty.
• US 6,289,952 B1 (filed 1999, granted 2001), "Pin router," assignee Lee Valley Tools Ltd. [PR14] — confirms continuing design activity into 1999–2001. A granted patent establishes a disclosed invention and assignee, not that a product was manufactured or sold. No catalogue, manual, archived product page or sales record was located for it.

Key evolution (Petroski lens), stated carefully. C.R. Onsrud's inverted router, in use since 1976, is a dated product change. The company's own framing, as relayed by the reviewer, includes a safety rationale [manual, relayed]; the Onsrud pages read in this pass did not state one. The layout puts most of the cutter below the table and work and keeps the template in view. That reduces direct exposure, but the cutter still reaches the point of operation, and the machine still needs the manufacturer's guard and a fixture that keeps hands outside the danger zone. The NIOSH case below is an overhead machine; this entry does not claim an inverted machine is immune to contact or to tool projection.

human side

Traditions & trades: furniture and cabinet production floors, sign-making, pattern-making, and lutherie (guitar and instrument body and neck production), the best-documented thread in the sources.

Cultures & regions: an American industrial-shop tradition (Onsrud, Chicago/Niles IL; J.A. Fay & Co., Cincinnati), still made new by a small set of manufacturers (Cantek, C.R. Onsrud) serving North American industrial and production shops.

Practitioner and collector accounts (attributed; none is a factory record):

• Fender's guitar factory, 1960s. A named professional luthier on a forum (TalkBass, Bruce Johnson's thread): "Fender's factory had a hundred of them in the '60's... These have been the foundation of solid body guitar making for the last 75 years" [PR16]. This is a practitioner's account. The count and the period are not independently verified, and no Fender factory record, period photograph, catalogue or museum document was found. The "1920s through the 1990s" production-dominance period in the original entry is likewise practitioner and trade-forum testimony [PR16][PR17], not established industrial history.
• Rick Kelly, Carmine Street Guitars, New York City — a working luthier filmed in the 2018 documentary Carmine Street Guitars using a large overarm pin router; discussed by a named cabinet-shop veteran in a Festool Owners Group thread: "A pin router's party-trick is being able to duplicate pockets on the opposite side of the project parts" [PR25][PR27].
• Gary Nava, a UK luthier, built an improvised pin router (a rotary tool in a drill-press stand with a shop-made pin) to cut F-holes in a carved archtop mandolin top, on his named blog: "The ideal way to cut the 'F' holes in a carved top is to use a pin router which, of course, I don't have. So, let's make one!" [PR26] This is one maker's improvised setup, not a recommended one, and its guarding and speed arrangement are not described as validated.
• Bruce Johnson, a named professional luthier, acquired two pin routers from a colleague's estate and keeps an ongoing (2019–present) forum thread on their production use, the entry's richest anatomy and technique source [PR16]. The practitioner discussion itself recommends handles to keep hands away from the cutter [manual, relayed].
• "Dadagoboi," Cataldo Basses — a named bass-building shop on the same thread: a small 120V pin router "will still cut a body perimeter with three passes in less than 5 minutes" [PR16].

Collectors' evidence, at its true level. A Telecaster Guitar Forum (TDPRI) thread on vintage-Fender authentication says Fender's pin-router fixtures were screwed to the workpiece, leaving two small witness holes on vintage bodies and necks, measured at "3 3/16″ from the neck plate... and 1″ from the bottom end of the body," and that the practice ran "until the late '70s when NC routers fully replaced the old-style pin routers" [PR24]. This is a forum discussion that describes an artifact. It was not an inspection of the artifact or a factory record, and a second forum discussing witness holes does not independently verify the number of machines or the dates.

The honest present-day standing, from a trade-forum consensus (WOODWEB): "The pin router is a good example of old technology that still works, especially for limited production or single custom parts... I can usually make a single custom part and have it finished before any computer programming is ready" [PR17].

proof of existence (for the Library of Human Making)

• Company record: Onsrud Machine Works, Inc., founded 1915 in Niles, Illinois, which "made woodworking machinery, especially pin routers, and high speed steel cutters for wood" [PR1]. A company milestone, not a tool-origin date. A conflicting 1912 date and the name "Ons-Rooter" appear in a single tertiary source and are flagged [PR4].
• Utility patents (mechanism): US 2,592,187 (1952) [PR7]; US 4,397,342 (1983), read in full [PR10]; US 4,779,327A (1988), read in full [PR11]. US 4,630,656 describes an equivalent-diameter pin and cutter for that attachment only [manual, relayed].
• Design patents (appearance only): US D187,715 and D188,088 (1960), Charles R. Onsrud and Robert Louis Deschamps [PR8][PR9].
• Patent evidence of continuing design activity: US 6,289,952 B1 (2001), Lee Valley Tools Ltd. [PR14]. Not evidence of manufacture or sale.
• Federal investigative record: NIOSH FACE Report 95MA020, DOI 10.26616/NIOSHSFACE95MA020 (read this pass) [PR15].
• Current-production evidence: Onsrud's and Cantek's current pages and spec sheets; a manufacturer-history claim of the inverted line since 1976 [PR3][PR20].
• Collectors' discussion (not an inspection): a forum thread on witness holes in vintage Fender bodies [PR24].
• Museum/collection records: none located.
• Removed from this list: US 1,528,536, which shows an adjustable overarm universal woodworking machine and does not establish a guide-pin or template-following mechanism, and US 3,099,298, "Router attachment for radial saw," which was cited as prior art and never opened in full. Neither is pin-router proof.

references

• [PR1] VintageMachinery.org — "Onsrud Machine Works, Inc." company history. vintagemachinery.org/mfgindex/detail.aspx?id=610. kind: archival/collection (read in Run 385).
• [PR2] VintageMachinery.org — "Onsrud Machine Works, Inc. – Assigned Patents." vintagemachinery.org/mfgindex/detail.aspx?id=610&tab=7. kind: archival/collection (read in Run 385).
• [PR3] C.R. Onsrud — "Inverted Routers." cronsrud.com/inverted-routers/. kind: builder-doc, manufacturer self-history (re-read this pass: 1915 claim, brake differences, 500 VS and 750 SS specs, secondary operations after CNC, pin and collet sizes; it did not itself state safety advantages).
• [PR4] Grokipedia, citing Australian Wood Review, "A brief history of woodworking machinery." woodreview.com.au/tools-and-equipment/a-brief-history-of-woodworking-machinery. kind: tertiary/AI-synthesized — low confidence [flag].
• [PR5] OWWM.org forum — "History of Pin Routers?" owwm.org/viewtopic.php?t=158064. kind: forum — unreachable, cached summary only [flag].
• [PR6] US Patent 1,685,572, "Woodworking machine," Oscar Onsrud, 1928 (filing date 1928; woodworking machine with work clamping and interlocked cutter control; does not resolve the 1912/1915 spindle claim).
• [PR7] US Patent 2,592,187, "Automatic guide pin for routing machines," Karl Rohrer, 1952. patents.google.com/patent/US2592187.
• [PR8] US Patent D187,715, "Contour-profiler machine," 1960. design patent: appearance only.
• [PR9] US Patent D188,088, "Router machine," 1960. design patent: appearance only.
• [PR10] US Patent 4,397,342A, "Pin-router mounting device and method," Joe E. North, 1983 (read in Run 385). It cites US 1,528,536 as prior art; that citation does not make the DeWalt patent pin-router ancestry.
• [PR11] US Patent 4,779,327A, "Drill press supported platform for pin router," Laddie J. Vander Maas, 1988 (read in Run 385).
• [PR12] US Patent 4,630,656, "Router Attachment." patents.google.com/patent/US4630656A. [manual, relayed]
• [PR13] US Patent 1,528,536, "Woodworking Machinery," Raymond DeWalt. patents.google.com/patent/US1528536A/en. Adjustable overarm universal woodworking machine; not pin-router lineage; listed only for the record of what was removed.
• [PR14] US Patent 6,289,952 B1, "Pin router," Lee Valley Tools Ltd., 2001. Evidence of design activity only.
• [PR15] NIOSH FACE Report 95MA020, "Massachusetts Woodworker Dies When Struck By Knife Launched from Overhead Router." stacks.cdc.gov/view/cdc/166628. DOI 10.26616/NIOSHSFACE95MA020 (re-read this pass).
• [PR16] Bruce Johnson, "Pin Routers: The Old-School Production Workhorses," TalkBass.com Luthier's Corner, started 2019-05-26. kind: forum, named practitioner; not a factory record.
• [PR17] "Using a Pin Router," WoodWeb Cabinetmaking Forum, 2009-06-04. kind: forum/trade.
• [PR18] David Jeffrey, "Pin Routing on the Drill Press," Fine Woodworking No. 88 (June 1991). finewoodworking.com/2005/10/25/pin-routing-on-the-drill-press (re-read this pass; see Variations).
• [PR19] Dennis R. Wilson, "The Pin Router," Fine Woodworking #29, Jul/Aug 1981. finewoodworking.com/1981/08/01/the-pin-router. Metadata/summary only; full text not read.
• [PR20] Cantek SR750 product page, Scarlett Inc. scarlettinc.com/new-machinery/woodworking-machinery/overarm-pin-router/. builder-doc; a spec sheet, not an operating manual.
• [PR21] Cantek SR750 pricing, Wurth Louis & Company. wurthlac.com/product/2530. dealer listing, July 2026, USD.
• [PR22] C.R. Onsrud #36210 inverted pin router listing (sold, $2,500), Surplus Record. dealer listing; an example, not a market range.
• [PR23] Macchine Casadei MK/1 overarm pin router, eBay sold listing ($2,806.24). marketplace listing; an example.
• [PR24] Telecaster Guitar Forum (TDPRI) — "Vintage Fender Necks Missing Pin Router Holes?" forum; discussion of an artifact, not an inspection.
• [PR25] Festool Owners Group forum — "Overarm Pin Router at Carmine Street Guitars." forum.
• [PR26] Gary Nava — "A Luthier's Blog: Top Plate II or, 'I want a pin router!'" guitar-maker.blogspot.com/2017/10. named-author blog.
• [PR27] Carmine Street Guitars (2018 documentary film, dir. Ron Mann), referenced via forum discussion [flag].
• [PR28] Router — Haft Tool Corpus (live). internal corpus.
• [PR29] Router Table — Haft Tool Corpus, Staging. internal corpus.
• [PR30] CNC Router — Haft Tool Corpus, Staging (Run 384). internal corpus; its lineage claim about the pin router is superseded by this entry's convergence account and should be corrected in its own fix pass.
• [PR31] woodworkingadvisor.com — "DIY Router Templates: How to Get the Bushing Offset Right." retailer/trade (contrast case).
• [PR32] Lee Valley — "Router Template Guides." retailer-doc (contrast case).
• [PR33] USDA Forest Service, Computer Numerical Control of Woodworking Machines in Secondary Manufacture (1983). srs.fs.usda.gov/pubs/gtr/gtr_so042.pdf (read this pass). Dates a numerically controlled routing and shaping machine to 1966; does not mention pin routers.
• [PR34] OSHA 29 CFR 1910.213, Woodworking machinery requirements. osha.gov/laws-regs/regulations/standardnumber/1910/1910.213 (read this pass).
• [PR35] OSHA, A Guide for Protecting Workers from Woodworking Hazards (publication 3157). osha.gov/sites/default/files/publications/osha3157.pdf (read this pass).
• [PR36] C.R. Onsrud tooling catalogue (hosted at microfence.com). microfence.com/wp-content/uploads/2017/04/Onsrud.pdf. The safety pages were not in the text available this pass; the drill-press warning is relayed from the review [manual, relayed].
• [PR37] C.R. Onsrud product-history blog. cronsrud.com/onsrud-blog/. Read this pass; it did not address the 1976 safety rationale. That rationale is relayed from the review as manufacturer self-history [manual, relayed].

The structural thesis — a hand-guided template system that CNC routing partly displaced

CNC Router's entry treated the pin router as the CNC router's lineage. This corrected copy does not. The honest history is convergence and substitution, not a single straight line.

• A pin router has no automatic or programmed path control. A fixed guide pin sits at the cutter's axis, a template bears against it, and the operator manually moves the fixture so the template stays in contact with the pin. The "program" is a physical object a shop-hand built, and the "control loop" is the operator's steering.
• CNC routing replaces that manual template following with programmed coordinate motion, executed by a controller and axis drives. The physical template is replaced by program data derived from geometry, and the operator's continuous steering by controlled relative motion. No single part (a stepper, a servo, a G-code file) stands in for the pin; the controller, the program, the drives, any position feedback and the machine mechanics together do. Not every CNC router uses steppers or G-code in the simplified desktop sense.
• The pin router is therefore an important functional and production antecedent: named practitioners report that CNC routers displaced much template-guided work. CNC woodworking itself descends from numerical-control machine-tool development, feedback and controller technology, programmed coordinates, and routing and shaping machinery. The USDA Forest Service's 1983 history of computer numerical control in woodworking (read this pass) says "A numerically controlled routing and shaping machine was introduced into the wood industry in 1966," and does not mention pin routers. "Direct ancestor" may be used only if a historical source explicitly documents that succession; none is cited here.

The second finding worth surfacing up front is a convention that differs from the sibling entries, stated as the common case, not a rule. Router and Router Table teach the hand-router discipline: a guide bushing commonly has an outside diameter larger than the cutter, so a template is built undersized by an offset, (bushing OD − bit diameter) ÷ 2. On a pin router, the common practitioner setup is the other way around: a named practitioner says "Normally, you use a pin that's the same diameter as the router bit that you are using for the job" [PR16], which gives a 1:1 relationship between the relevant template boundary and the cut. That is a configuration to verify, not a universal assumption: see Anatomy and the beginner-trap.

The reviewer's corrections (24)

• BLOCKER — 1. Replace the exclusive direct-ancestor thesis — Exact claim: “The CNC router's true lineage runs through the pin router, not through the metal-cutting CNC machining center,” and the pin router is the “direct mechanical ancestor of the CNC router.”
• BLOCKER — 2. Correct the pin-to-stepper analogy — Exact claim: CNC “replaced the hand with a stored toolpath, the pin with a stepper motor, and the template with a G-code file.”
• SHOULD-FIX — 3. Separate company history from tool origin — Exact claim: Onsrud's 1915 founding is the entry's “Origin — company record,” later restated as the earliest record of a company founded “specifically to make pin routers.”
• SHOULD-FIX — 4. Resolve the 1912/1915 spindle story with an exact patent — Exact claim: Oscar and Rudolph Onsrud invented and patented the first air-powered high-speed spindle in 1915, while a tertiary source gives 1912 and “Ons-Rooter.”
• BLOCKER — 5. Remove US 1,528,536 from the pin-router lineage — Exact claim: US 1,528,536 “independently push[es] the documented lineage of router-arm/pin-guided devices back to the early 1920s.”
• SHOULD-FIX — 6. Do not use design patents as mechanism proof — Exact claim: D187,715 and D188,088 show Charlie Onsrud “patenting pin-router designs” and help form a “real, independently verified patent trail.”
• SHOULD-FIX — 7. Separate patenting from commercial manufacture — Exact claim: Lee Valley's US 6,289,952 “confirms the tool class remained commercially patented and manufactured into the CNC era.”
• SHOULD-FIX — 8. Downgrade production-dominance and Fender claims — Exact claim: Pin routers “dominated” furniture/lutherie floors from the 1920s through the 1990s; Fender had one hundred in the 1960s; witness holes independently corroborate the factory claim.
• SHOULD-FIX — 9. Change “zero offset” from universal rule to normal configuration — Exact claim: “The guide pin is matched to the exact diameter of the bit,” templates are always actual size, and this is “zero offset by design.”
• MINOR — 10. Remove “always” from the bushing comparison — Exact claim: A router guide bushing is “always larger-OD than the bit.”
• SHOULD-FIX — 11. Broaden the identity beyond one C-frame machine — Exact claim: A pin router is a “rigid C-frame machine” with the spindle above or below a table.
• MINOR — 12. Replace “no self-guidance at all” — Exact claim: A pin router has “no self-guidance at all.”
• BLOCKER — 13. Stop describing the inverted design as making hands safe by itself — Exact claim: The inverted router is an explicit safety fix, with “hands away from the cutter,” while the overhead cutter sits directly above the operator's hands.
• BLOCKER — 14. Add point-of-operation guarding as a primary control — Exact claim: The operating summary says to keep both hands on the fixture but gives no guard requirement.
• SHOULD-FIX — 15. Correct the reaction-torque/spindle-brake causation — Exact claim: Patent language about reaction torque is “the documented reason” commercial pin routers include an automatic brake.
• BLOCKER — 16. Replace “hands on fixture” with engineered fixture control — Exact claim: “Keep both hands on the fixture” is presented as the core safe technique and “hands-on-template, hands-off-cutter” as the machine's design.
• BLOCKER — 17. Clarify or remove the drill-press “zero-cost conversion” — Exact claim: A Fine Woodworking tip provides a “real, dated, zero-cost hobbyist access path” by converting a drill press into a temporary inverted pin router.
• BLOCKER — 18. Complete the operating-safety system — Exact claim: The “heaviest” misuse section focuses on incompatible tooling, multiple passes, template offset, and CNC confusion.
• BLOCKER — 19. Remove “unattended repeat runs” from the CNC comparison — Exact claim: A pin router cannot replace a CNC router for “unattended repeat runs.”
• SHOULD-FIX — 20. Resolve one-off matching contradictions — Exact claim: The entry says a true one-off is a job the tool “should never do,” while elsewhere it says a single custom part can be finished before CNC programming and presents one-off work as part of the revival case.
• SHOULD-FIX — 21. Remove the “redundant once G-code exists” exclusion — Exact claim: A pin router is not for any shop already using a CNC router for volume production because the parallel template system is redundant.
• SHOULD-FIX — 22. Correct the ownership weight and power generalization — Exact claim: Used/vintage ownership means “500–3,000 lb industrial machines needing three-phase power.”
• MINOR — 23. Date volatile pricing and market counts — Exact claim: New machines sell for $13,300–$14,400 through at least eight distributors, with used examples at exact prices.
• SHOULD-FIX — 24. Lower confidence until the core claims are repaired — Exact claim: MEDIUM-HIGH confidence is justified by patents, NIOSH, archival history, and practitioner evidence.