US 2457829

I'll verify against live sources before summarizing.

Let me check for any post-issuance records (assignment, reissue, litigation) tied to this number.

US Patent 2,457,829 — Summary

Bottom line: I found authoritative full text for this patent on Google Patents and confirmed its bibliographic data. I found no CAFC 2026 docket, PTAB proceeding, district-court case, or reexamination involving US 2,457,829, and no assignee other than an individual inventor. Several near-miss identifiers surfaced and are not this patent (see "False hits" below).

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Bibliographic data (as indexed)

Abstract

There is no authoritative formal abstract for this patent. It issued in 1949, before abstracts were standard on U.S. patents, and the Google Patents page has no abstract field — the section headed "Definitions" is OCR-scraped fragments of the specification, not an abstract. The following is my spec-derived summary, not a quotation of an official abstract:

A portable, motor-driven hand hacksaw in which a standard hacksaw blade is carried in a conventional frame. The frame hangs from the underside of an elongated tubular housing and is reciprocated by a follower that rides in an endless, doubled-back spiral groove machined into a rotary drive shaft inside the housing. The housing is bolted to a reduction-gear-equipped electric motor at one end, reinforced near that flange by a ribbed tubular brace, and fitted with a shaped guide handle that can be either gripped or pushed against with the palm.

Plain-language overview of the independent claims

All four claims read as independent (claim 4 is essentially claim 2 with the specific arm-angle limitation removed). All share one core inventive concept: rotary-to-reciprocating conversion via an endless doubled-back spiral groove on a rotating shaft, with the saw frame suspended from the shaft and thrust reacted into the housing.

Claim 1 — the base machine. A power-driven hand hacksaw with: (a) a prime mover; (b) an elongated tubular housing; (c) a drive shaft in the housing bearing a spiral guide "doubled back on itself" to form an endless and returning path; (d) a drive connection from prime mover to shaft; (e) a blade-mounting frame; (f) a hanger projecting from the top of the frame up into the housing through a narrow slit; (g) a bearing on the hanger that rotatably receives the drive shaft; (h) a swivelly mounted follower carried by the hanger, riding the spiral guide to drive the frame back and forth; (i) low-friction means on the hanger riding the housing's inner surface to transmit blade thrust into the housing; and (j)(k) flange means joining the housing to the prime mover plus a ribbed reinforcing sleeve (tubular section with a flange abutting the first flange and longitudinal ribs) stiffening the housing adjacent that joint.

Claim 2 — machine plus the shaped guide handle. Adds a handle made of a connecting section with one arm projecting generally normal to it (extending end offset laterally to one side) and a second arm at less than 90° (extending end offset laterally to the other side), with angularly disposed fastening lugs on both arm ends. The handle mounts so that one lug sits to the side of the housing and the other sits near the housing top and further from the prime mover — the geometry that lets the operator either grip it with fingers or press the palm against it as an abutment.

Claim 3 — the slit/hanger sub-combination. Written as "In a power-driven hand hacksaw," it claims a tubular housing with a lengthwise slit, the grooved drive shaft, the blade frame, a plurality of spaced-apart hanger members passing through the slit into the housing, low-friction means against the inner housing surface for thrust transmission, and a swivelly mounted follower carried by one of those hanger members. The plural-hanger limitation is the notable difference from claims 1–2.

Claim 4 — machine plus a broader handle claim. Same elements as claim 2 (prime mover, tubular housing, endless-groove shaft, drive connection, frame, hanger, bearing, swivel follower, low-friction thrust transfer), but the handle is recited without the "less than 90°" limitation — just "another arm ... having its extending end disposed laterally of said connecting section to the other side." The mounting-lug positioning language is retained. Practically, this is a fallback to the claim-2 handle concept at broader scope.

Disclosure highlights relevant to claim scope

• The specification states the stroke length is set by the length of the endless thread, giving a stroke "comparable in length to the normal stroke in manual operation," and claims a substantially constant stroke speed through the travel.
• It expressly addresses manual operation: the blade can be drawn back and forth by hand over the work to start a cut, and it discusses preventing reverse-driving of the motor by providing a slightly high-friction area at a groove reversal point so the follower parks in a "closed center" position. The patentee explicitly disclaims being bound by that theory.
• The reader bearings (bronze members 6 and 11) and the roller bearings (20, on axles 22, riding trackways 18) are described as taking rotational friction and the upward cutting reaction, respectively.

CAFC 2026 / litigation search result

• No CAFC docket, appeal, PTAB trial, district-court action, or reexamination for US 2,457,829 was found. Practically, the patent expired January 4, 1966, so it could not support an infringement suit or IPR in 2026; it would appear only as prior art.
• False hits — do not conflate: (1) EP 2 449 782, the patent at issue in the UPC Court of Appeal Amazon v. InterDigital preliminary order dated Feb. 2, 2026 (UPC_CFI_936/2025) — a European patent, not US 2,457,829. (2) RU 2457829 C2, a 2012 Russian patent on a mineral/vitamin tooth-enamel complex — unrelated subject matter. (3) Japanese and other family-annex tables surfaced for unrelated numbers.
• Uncertainty: I could not verify assignment history, an inventor's death/dedication record, or any terminal disclaimer from an authoritative USPTO source; the Google Patents notice itself states its assignee/legal-status fields are assumptions, not legal conclusions. I also cannot rule out that a 2026 filing mentions this patent as prior art without the number appearing in my search results.

I'll search for litigation involving US patent 2457829.

Let me search litigation-specific sources.

Litigation Search Results: US Patent 2,457,829

Bottom line: I found no litigation involving US Patent 2,457,829. No lawsuits appear to be indexed for this patent.

What I searched

I ran queries aimed at the litigation databases you specified, including:

• General patent-litigation queries for "2457829" (Google Patents, and litigation-oriented phrasing)
• Unified Patents‑style queries ("2457829" + litigation/Unified Patents)
• CAFC/PACER-oriented queries ("2457829" complaint/defendant, CAFC infringement suit)
• Queries using the comma-formatted number ("2,457,829") and inventor name + "infringement"

All returned zero results naming this patent in any case. The only substantive hits were the Google Patents page for US2457829A itself and an unrelated CAFC opinion (DePuy Spine v. Medtronic, No. 2008‑1240) that does not involve this patent.

No case data to report

Because no litigation was located, I cannot provide the requested fields (plaintiff, defendant, jurisdiction, case number, filing date, outcome/status) — there is no case to populate them with. I am not going to fabricate entries.

Context that explains the "no results" (with the caveat that this is reasoning, not a litigation record)

• Patent identity: US 2,457,829, "Power driven hand racksaw," inventor Charles D. Miller, filed June 3, 1944, granted January 4, 1949. Source: https://patents.google.com/patent/US2457829/en
• Assignee: Listed as "Individual" (original and current). A lone individual inventor‑owner is far less likely to appear in commercial patent‑assertion dockets than a corporate portfolio holder.
• Legal status: Expired – Lifetime, with an anticipated expiration of January 4, 1966 per the Google Patents record. A patent that expired in 1966 (and whose enforceable window was in the 1949–1966 era) would not appear in modern litigation databases such as Unified Patents' portal, which generally track the post‑2000 litigation era. Pre‑1966 district court cases are largely absent from these digital indexes.
• Government-interest clause: The specification carries the standard "Granted under the Act of March 3, 1883, as amended April 30, 1928" recitation (permitting government manufacture/use without royalty), which is consistent with a government‑interest patent rather than a commercial assertion campaign.

Confidence and limitations — please read

• Confidence that there is no currently indexed litigation: high. Repeated targeted searches returned nothing.
• Confidence that there was never any litigation anywhere: low. Pre‑1966 federal cases are poorly digitized. My tools cover patent‑litigation databases and general web sources, but I did not obtain a direct, case‑by‑case result from the Unified Patents litigation portal, nor a PACER docket search, nor a Westlaw/Lexis full‑text historical case search. A 1949–1966 infringement suit, if one existed, could plausibly exist in paper or non‑digitized records not surfaced here.
• If you need a definitive negative, the authoritative next steps would be a PACER docket search for "Miller" / hacksaw cases in the relevant districts (e.g., Iowa, where the inventor was from — Davenport, Iowa, per the specification), and a Westlaw/Lexis or Bloomberg Law historical case‑law search for "2,457,829" and "Miller" + "hacksaw," which cover older reported decisions that Unified Patents does not.

Sources cited:

• https://patents.google.com/patent/US2457829/en (bibliographic data, legal status, assignee)
• CAFC opinion No. 2008‑1240 (http://cafc.uscourts.gov/sites/default/files/opinions-orders/08-1240.pdf) — reviewed and confirmed as unrelated to this patent

If you can point me to a specific district or a date range, I can run a narrower follow‑up, but on the current record I must report: no known litigation for US Patent 2,457,829.

I'll verify the absence of PTAB activity before writing up the analysis.

Proceedings overview

Total AIA trial proceedings on file for US 2,457,829: zero (0). Breakdown: 0 active, 0 with claims invalidated, 0 with claims sustained, 0 settled, 0 institution denials. The USPTO Open Data Portal returns no IPR, PGR, or CBM proceeding against this patent, and my independent searching surfaced none — no PTAB Final Written Decision, no institution decision, no Federal Circuit appeal, and no defensive-aggregator (Unified Patents, RPX, etc.) challenge in the chain. Bottom line for a defendant: there is no "hardened patent" and no "patent that survived IPRs" story here — there is no PTAB record at all, because US 2,457,829 issued on 1949-01-04, expired on 1966-01-04, and has now been off term for roughly six decades. A demand letter citing this patent is not a validity fight; it is a citation error or an outright fraud on the recipient.

No proceedings to report — the empty set, verified

• Structured source (canonical): "PTAB proceedings on file" block returns no AIA trial proceedings as of the most recent ODP ingest. Legal status is recorded as Expired - Lifetime, anticipated expiration 1966-01-04.
• Independent verification (web search, 2026-10-01): Searches for PTAB/IPR/CBM/PGR activity against US 2,457,829 or "2,457,829" produced no PTAB or CAFC docket. The hits were unrelated: Russian patent RU2457829C2 (a toothpaste mineral complex), EP2457829 (helicopter blade), USDOT No. 2457829 (a motor carrier), and an unrelated distributor part number. None of these is a proceeding against this patent.
• Do not treat Google Patents' "Cited By" / "Citations" tables as trial data. Those entries (US2668567 Olson 1954; US4505037 Farkas 1985; US5313709 Commonwealth of Puerto Rico 1994; US6256891 Van Camp 2001; US6925719 / US20050115085 Callne 2003–2005; Black & Decker 2014–2020 family; Zhi Long (H.K.) 2013–2019 family) are forward patent citations, not PTAB proceedings. No petitioner–patent-owner relationship exists in any of them.
• A note on why no IPR was ever filed. Expiration is not, by itself, a statutory bar to IPR — the Board has instituted trials on expired patents where a live dispute over back damages existed. Here the practical bar is temporal and absolute: the 17-year term from the 1949-01-04 grant ran out on 1966-01-04, more than 59 years before today's date. Damages are time-barred under 35 U.S.C. § 286, prospective infringement is impossible under § 271, and no party has had a financial reason to petition since the Johnson administration.

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Defensive posture: what this means for a defendant today

• Claim 1 — untested, and untestable now. No FWD ever construed, canceled, or sustained it. But the patent expired 1966-01-04, so claims 1–4 cannot be infringed by any current or future product. There is no live case to defend.
• Claims 2, 3, 4 — same. The patent carries four claims on the face of the printed document (claims 1 and 2 recite the prime-mover/housing/endless-thread combination; claim 3 is the "plurality of spaced apart hanger members" species claim; claim 4 is a handle-focused variant of claim 2). OCR of the printed specification is badly garbled and runs claim 1's text into claim 2's in places — if claim text ever matters, pull the PDF from the source record rather than a text scrape: https://patents.google.com/patent/US2457829/en
• Government license is baked in. The specification opens with the standard wartime clause: "The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon." Even during term, the U.S. Government held a royalty-free license. (Provenance for claim-by-claim text: the printed patent and its 12 cited references, listed in the file wrapper.)
• Defensive value: 1–2 sentences. If you are a defendant being asserted against on US 2,457,829, the dispositive point is that the patent has been expired since 1966-01-04 — there is no enforceable claim to invalidate, so no IPR is even the right tool. The correct response is a demand for the asserting party to identify the actual live patent number it means to assert, and, if it persists, a note that asserting an expired patent exposes it to Rule 11 sanctions under Fed. R. Civ. P. 11(b)(2)–(3) and a potential § 285 / state unfair-competition claim.

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Strategic summary

Claim status: 0 canceled, 0 sustained by the Board, 4 untested — and all 4 expired. Because no AIA trial was ever instituted, there is no FWD to parse for claim-level dispositions, no certificate of cancellation or confirmations under 35 U.S.C. § 318(b), and no Federal Circuit mandate. The only authoritative statement of claim scope is the printed document itself. Claim 1 covers the combination of a prime mover, an elongated tubular housing, a drive shaft with an endless returning spiral guide, a hanger-mounted frame carrying a saw blade, a swiveled follower, low-friction thrust transfer to the housing, and a flanged ribbed reinforcing structure adjacent the prime-mover attachment. Claim 3 adds a plurality of spaced-apart hanger members entering through a longitudinal slit in the housing. Claim 4 shifts to the specific handle geometry — a connecting section with a generally normal arm on one side and an arm at less than 90° on the other, each with angularly disposed fastening lugs. All of that is now public-domain engineering.

Estoppel landscape: no estoppel exists, in either direction. Section 315(e)(2) estoppel is triggered only by a final written decision in an instituted IPR — there is none, so no petitioner, real party in interest, or privy is estopped from anything. Conversely, no patent owner has had a claim confirmed, so there is no § 315(e)(1) or § 325(e)(1) registration estoppel protecting the claims either. There are also no Sotera-type stipulations, no § 315(b) one-year time-bar records, and no Fintiv discretionary-denial history to mine. Any "prior art still available" analysis is academic: the patent expired long before the AIA's first petition even existed.

Pattern signals: none of the usual troll/Section-327 tell-tales appear. No repeat petitioner filed multiple IPRs (there have been zero); no patent owner pursued PTAB appeals (there is nothing to appeal); no defensive aggregator appears anywhere in the chain. The patent's ownership history shows Individual as both original and current assignee — no acquisition by a monetization entity, no recorded assignment activity in the ODP data. The patent is historically, not commercially, interesting: it is cited by more than a dozen later portable-saw patents as background art (Olson, Farkas, Puerto Rico's 1993 conversion attachment, Van Camp, Callne, the Black & Decker accessory family), which is exactly the profile of a foundational-but-decades-dead reference rather than a live assertion target.

One housekeeping flag. The structured record and Google Patents list the title as "Power driven hand racksaw" while the printed patent's own header reads "POWER-DRIVEN HAND HACKSAW" and the inventor is Charles D. Miller of Davenport, Iowa. Per the operating instruction to interpret identifiers literally, I have not corrected the title in the record — but the discrepancy is an OCR artifact, not two different patents. If you are matching this number against a demand letter, confirm whether the letter's author pulled the title from the same OCR'd source.

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Recommended next steps

• No PTAB activity exists — say it plainly. The absence is not a merit signal; it is a timing signal. Well-asserted patents attract IPRs within a few years of assertion. A 1949 patent with a 1966 expiration date never had an AIA-era window, so the zero count carries a much stronger message than it would for a 2015 patent: there is no validity controversy because there is no patent. There is no FWD to link to, no institution decision to quote, and no CAFC docket to check. Do not manufacture one.
• If you receive a demand citing US 2,457,829: respond in writing, cite the expiration date 1966-01-04, demand the asserting party identify the specific live patent and claim it contends you infringe, and reserve Rule 11 and § 285 remedies. Preserve the letter and any pre-suit communications — if the sender is recycling an expired patent number as part of a broader demand campaign, that document set is the evidence.
• If you are investigating the technology rather than the patent: the useful artifacts are the 12 references cited on the face of the patent — in particular US2330618 (Plumb, "Portable electric hack saw," 1943-09-28) and US2329729 (Saucke, "Portable cutting tool," 1943-09-21), both granted within a year of the 1944-06-03 filing date — plus the foreign reference Swedish Patent 100,137 (1940-10-29). These, not any PTAB record, are the prior-art neighborhood to search if a live descendant patent ever cites Miller as background art.
• Verification endpoints. PTAB trial records: https://ptab.uspto.gov (PTAB E2E) and https://developer.uspto.gov/api-catalog/odp (Open Data Portal, the canonical source for this empty result set). Printing/prosecution record: https://patents.google.com/patent/US2457829/en. For any future assertion of a different patent number that a demand letter attributes to "Miller," run the same search pattern used here — that is the check that produced this zero.

I'll research the ownership chain for US 2,457,829.

Inventors

Findings and caveats:

• Sole inventor. There is no co-inventor, so no "all inventors depart within 12 months" pattern is assessable — that pattern requires a multi-inventor team rotating out of an assignee.
• The specification carries the standard government-interest recitation ("Granted under the Act of March 3, 1883, as amended April 30, 1928"), i.e., the pre-AIA military/Government-interest license language. This appears routinely on WWII-era filings by individual inventors and is not evidence that the Government was an assignee or employer here — the patent's own front page lists the assignee as "Individual." I flag it only because it is a recurring confusion point; I do not treat it as an assignment record.
• Davenport, Iowa is a heavy-manufacturing city (farm equipment, rail-car, and small-tool shops of that era). It would be reasonable to hypothesize that Miller worked for one of those firms, but no source I retrieved establishes any employer. I will not guess. If an employer existed and took no assignment, that is itself consistent with the "Individual" assignee designation.

Anomalous patterns: none detectable. A single inventor filing individually and retaining the patent is the baseline case, not an anomaly.

Original assignee

• Original assignee of record: none. Under "Original Assignee" and "Current Assignee," the Google Patents record for US 2,457,829A states "Individual". Title issued to Charles D. Miller personally; there is no corporate assignee on the face of the patent.
• Product shipment embodying the claims: No evidence of any commercial product. The disclosure describes a hand-held power hacksaw built around a conventional electric motor (element 1) with a reduction gear housing (35), a tubular drive housing (23), and an endless-thread drive shaft (9) driving a blade frame (31) via a swivel follower (25/39). Nothing in the record — no trademark, no manufacturer name, no catalog reference, no cited-by product literature — ties this to a shipped article. I cannot state that it was commercialized, and I found no evidence that it was.
• Primary line of business: Unknown; no entity to attribute one to.
• Current status: The patent itself is Expired – Lifetime, with an anticipated expiration of January 4, 1966. Whatever rights existed were owned by an individual, lapsed five decades ago, and there is no successor entity of record. Any "current owner" is a null set.

This is the critical structural fact for the rest of the analysis: there is no operating company in this chain to be acquired, to go bankrupt, or to sell anything.

Assignment timeline

The USPTO Assignment Center contains no recorded assignment that I could surface for US 2,457,829.

I must be precise about what this statement rests on, because it is a negative finding:

• What I verified: The patent's own bibliographic record (Google Patents, sourced from USPTO data) lists both the Original Assignee and the Current Assignee as "Individual." If a chain of title had been recorded post-issuance, the Current Assignee field would normally reflect the last-recorded assignee. It does not. The record also shows no reassignment entries among the legal events and no successor/subsidiary family applications.
• What I could not verify directly: I do not have a live connection to the Assignment Center's search backend (assignmentcenter.uspto.gov / assignment.uspto.gov). My retrievals of that index returned nothing usable, so I could not obtain a "0 records" confirmation screen, and I therefore have no reel/frame numbers, no conveyance types, no execution dates, no recording dates, and no correspondents of record to report. Every field the task asks for in this section is unavailable for that reason.
• What this means: I am reporting an absence of assignment records, not a confirmed all-records-negative search result. For a patent of this vintage the practical meaning is the same — the inventor retained title and the patent died with him — but the evidentiary distinction matters and I am not smoothing it over.

No fabricated entries follow. Because there are no records, there is no correspondent string to analyze, which disables signal #3 (repeat correspondent) entirely — a signal that requires recurrence across at least two recorded links.

Two corrections to flag from earlier work: The "Litigation summary" section above cites a "Granted under the Act of March 3, 1883" clause as being "consistent with a government-interest patent rather than a commercial assertion campaign." That recitation is a standard printed notice on patents of this era and carries no probative weight about ownership or assertion intent; it should not be counted as evidence in either direction. Separately, the earlier section's framing of "no current assignee listed as a corporation" is correct and is the load-bearing fact here.

Timeline diagram

timeline
    title Ownership of US 2457829
    1944 : Filed 3 June by Charles D Miller
    1949 : Patent issued 4 Jan
         : Assignee of record is Individual
         : No recorded assignment found
    1966 : Term expires 4 Jan
         : No successor owner of record

NPE / troll-pattern signals

Baseline for all eight signals: the chain has exactly one node — the individual inventor — and no recorded transfers. There is no movement of the patent from anyone to anyone, so most of these signals are structurally inapplicable rather than merely unsupported. I mark them accordingly rather than manufacturing "unclear" calls.

1. Shell-entity transfer — NOT PRESENT.
No assignment to any LLC appears in the record. No assignee with an IP/Patents/Licensing/Holdings/Ventures suffix exists in this chain. There is no reel/frame to cite, and the absence is not because a record is hidden — it is because the Current Assignee field still reads "Individual."

2. Known asserter in the chain — NOT PRESENT.
Neither the original nor the current assignee matches any public NPE list (Acacia, Marathon, IV, IPNav, Wi-LAN, Mosaid/Conversant, Vringo, Pendrell, Innovatio, MPHJ, Lumen View, Round Rock, Document Generation Corp, Spangenberg entities). The named assignee is a natural person in Davenport, Iowa. This is not an inference from a name — it is the absence of any assignee name at all.

3. Repeat correspondent across the chain — NOT PRESENT / UNAVAILABLE.
Signal cannot arise: there is only one link, and no correspondent of record is exposed anywhere in the data I could retrieve. A single correspondent is expressly not a finding under the task's own rule, and here there are not even one.

4. Cascading transfers — NOT PRESENT.
Zero consecutive assignments, therefore zero chained LLCs, therefore no shared correspondent address or common principals to test. The <24-month cascade test has no transactions to evaluate.

5. Pre-litigation transfer — NOT PRESENT.
There is no assignment at all, and per the earlier litigation section there is no infringement suit naming this patent. With no suit and no transfer, this signal has neither of its two required elements.

6. Bankruptcy fire-sale — NOT PRESENT.
The original owner is an individual, not a corporation; individuals do not file the Chapter 7/11 patent-sale proceedings contemplated by this signal (Kodak, Nortel, Polaroid, Sun→Oracle). No bankruptcy docket, no 363 sale, no SEC filing exists to check. This is the clearest structural non-signal in the set.

7. Privateering — NOT PRESENT.
Privateering requires an operating company with competitors to assert against. There is no operating company in this chain, no transfer to an NPE, and no patentee-versus-competitor posture. No SEC or Patent Progress / EFF coverage exists or could exist for a sole-inventor 1944 filing.

8. Defensive aggregator — NOT PRESENT.
The chain does not terminate at RPX, AST, LOT, Unified Patents, or OIN. It terminates at expiry on 1966-01-04 with title still in the individual inventor. The patent is "neutralized" only in the sense that it has been dead since 1966 — but that is statutory term expiry, not defensive acquisition, and conflating the two would be a category error.

Aggregate: 0 of 8 signals present. No strong signals, no weak signals.

Verdict

Insufficient data.

The verdict is driven by the record's emptiness in the specific way the task anticipates: US 2,457,829 lists "Individual" as both original and current assignee, no post-issuance assignment could be surfaced, and no reel/frame entries exist to cite. With a single-node chain terminating at a sole inventor, a 1966-01-04 expiry, and no infringement suit naming the patent (consistent with the earlier litigation section's negative finding), there is no acquisition, fire-sale, or transfer-to-asserter event to characterize, and therefore no NPE pattern to score.

Stated plainly: this is not "NPE — 0 signals." It is "no chain to score." Those are different findings and the distinction is the honest one here. A 1949 patent that expired in 1966 and was never assigned anywhere is simply an expired sole-inventor patent.

Verification link: https://assignmentcenter.uspto.gov/ (search patent number 2457829) — mirrored at https://assignment.uspto.gov/patent/index.html. A direct query of the Assignment Center by someone with live access would convert my "no records surfaced" into a definitive negative; that is the one gap in this report worth closing. The patent's bibliographic record confirming the "Individual" assignee designation is at https://patents.google.com/patent/US2457829/en.

I'll verify each cited reference against live sources before assessing anticipation.

Prior-Art Analysis — US 2,457,829 ("Power-Driven Hand Hacksaw")

Analysis date: April 26, 2026 per this task; note the earlier-generated sections in this file are timestamped 2026-10-01. Flagging that inconsistency rather than silently reconciling it.

Scope note: The prior art for this patent is unusually well defined because the patent itself carries a "References Cited" list of 12 U.S. patents + 1 Swedish patent. I treated that list as the authoritative universe, per the instruction to work through each citation. All references on that list pre-date the June 3, 1944 filing date.

Verification status — read this first. With limited search budget I was able to open and read the full text of only four of the thirteen references: Plumb 2,330,618, Saucke 2,329,729, Wappat 1,830,580, and Bowen 1,763,500. For the other nine I have the citation metadata (number, inventor, dates) from the patent's own reference table and from the Google Patents citation table, but not the reference's disclosure content. Where I describe content for those nine, I mark it [unverified]. I will not assert what an unread reference teaches.

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1. The § 102 framework that applies here

This patent was filed June 3, 1944 — squarely pre-AIA. So the operative statute is pre-AIA 35 U.S.C. § 102, and the critical date for the one-year statutory bar is June 3, 1943.

Two consequences matter for mapping references to claims:

• Eleven references (Gilbert through the Swedish patent) published more than one year before filing → available under both § 102(a) and § 102(b).
• Two references — Saucke 2,329,729 (granted Sept. 21, 1943) and Plumb 2,330,618 (granted Sept. 28, 1943) — issued within one year of the June 3, 1944 filing. They are therefore § 102(a) art only (patented before the applicant's invention); they are not § 102(b) statutory bars. The patent's own table lists them by grant date, consistent with the Google citation records.

[unverified] Sweden 100,137 (Oct. 29, 1940) is the only foreign reference; under pre-AIA § 102(a)/(b) its date alone qualifies it, but I could not read its disclosure.

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2. Master table of cited references

Dates are as listed in the patent's "References Cited" (grant dates) cross-checked against the Google Patents citation table (which also supplies priority/filing dates). Source: https://patents.google.com/patent/US2457829/en

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3. Reference-by-reference analysis

3.1 US 2,330,618 — Plumb, "Portable electric hack saw" (the most material reference)

• Full citation: E. W. Plumb, "Portable electric hack saw," US 2,330,618, granted Sept. 28, 1943 (filed July 14, 1941).
• Source verified: https://patents.google.com/patent/[US2330618A](/patent/US2330618A)/en
• What it discloses: A portable power hacksaw with a hacksaw blade 10 held in a frame 16 (holding members 13/14 on frame legs 15/17, one blade end on a clamp screw 18). The frame carries two spaced-apart pairs of rollers 21, 22 that ride in elongated slots 23, 24 in guide bars 25/26, the guide bars being bolted directly to the electric motor casing 28. An inclined handle 33 with a switch 34, plus a second handle 35. The frame is mounted in anti-friction bearings; the patent also discusses varying stroke speed and a stationary anvil held against the work.
• Claim mapping (§ 102):
  • Claim 1 — no anticipation. Plumb lacks the elongated tubular housing, the rotary drive shaft with an endless doubled-back spiral guide, the slit-crossing hanger, the swivelly mounted follower, the flange/prime-mover joint, and the ribbed reinforcing sleeve.
  • Claim 2 — no anticipation (no tubular housing, no handle of the claimed two-arm/lug geometry).
  • Claim 3 — no anticipation, but the closest structural correspondence of any reference to the "plurality of spaced-apart hanger members ... extending into said housing through the slit." Plumb's two spaced roller pairs bridging frame-to-guide-bars are the functional analogue of plural frame-to-housing load-transfer points. The difference is decisive: Plumb's rollers ride externally in slots on guide bars bolted to the motor casing, not through a lengthwise slit into the interior of a tubular housing onto the housing's inner surface.
  • Claim 4 — no anticipation.
• Bottom line: Best characterized as § 103 art on the "portable hand hacksaw frame guided on anti-friction rollers with thrust reacted into the motor housing" concept. It does not anticipate any claim.

3.2 US 2,329,729 — Saucke, "Portable cutting tool"

• Full citation: H. Saucke, "Portable cutting tool," US 2,329,729, granted Sept. 21, 1943 (filed May 4, 1942).
• Source verified: https://www.freepatentsonline.com/2329729.html
• What it discloses: A housing 10 with a driving motor 11 and two handles 12, 13. A pair of guide rails 15 in the housing mount a slide 16 for longitudinal movement. The slide carries a frame 17 with fingers 18/20 holding a hacksaw blade 19 (one end adjustable via screw 2x and arm). Drive is a sprocket 16' + chain 27 with a pivoted link 33 connecting the slide to a chain link, with stop members 34 and chain guides 32. Adjustable work-clamping jaws 40/45 with an adjusting rod 47/sleeve 46/spring 61.
• Claim mapping (§ 102):
  • Claim 1 — no anticipation. Saucke's rotary-to-reciprocating conversion is chain-and-link, not an endless doubled-back spiral guide on the drive shaft; there is no tubular housing/hanger/slit/swivel-follower combination, no low-friction rider on a housing inner surface, and no ribbed reinforcing sleeve at a flange joint.
  • Claims 2, 3, 4 — no anticipation. Same missing elements; additionally no handle of the claimed geometry and no plural slit-crossing hangers.
• Bottom line: Relevant § 103 art for the general proposition that a portable motor-driven tool housing may carry a slide/frame reciprocated to drive a hacksaw blade, and that a rotary motor output is converted to rectilinear blade motion. No § 102 anticipation. Note its § 102(a)-only status (granted ~8.5 months before the 1944 filing).

3.3 US 1,763,500 — Bowen, "Saw" (closest on the drive-conversion concept)

• Full citation: C. A. Bowen, "Saw," US 1,763,500, granted June 10, 1930 (filed Oct. 31, 1927).
• Source verified: https://patents.google.com/patent/[US1763500A](/patent/US1763500A)/en
• What it discloses: An electric motor 5 in a casing 1 with a handle and adjacent switch; a gear train driving a rotary cam drum 13 on shaft 36; the drum imparts reciprocatory movement to a plunger rod 19 guided in a rectangular way in the casing cover 15; and a clutch means for attaching the saw blade to the reciprocatory plunger rod. Objects include making the device "under the control of the operator" and using gearing to give rapid reciprocation.
• Claim mapping (§ 102):
  • Claim 1 — no anticipation, but this is the single best reference on "converting continuous rotation into reciprocation inside a portable motor housing by a rotary member, with the blade driven by a reciprocating member." Bowen still lacks the elongated tubular housing, the doubly-spiraled endless groove on a rotating drive shaft, the hanger projecting up through a narrow slit, the bearing-on-hanger rotatably receiving the drive shaft, the swivelly mounted follower, the low-friction thrust-transfer rider, the flange means, and the ribbed reinforcing structure. Critically, in Bowen the saw is attached directly to the plunger rod, not carried on a frame suspended beneath a tubular housing by a hanger.
  • Claims 2, 3, 4 — no anticipation (no claimed handle geometry; no plural hangers).
• Bottom line: Strong § 103 art for the drive-conversion and "motor casing + handle + switch + reciprocating blade mount" environment; no § 102 anticipation of any claim.

3.4 US 1,830,580 — Wappat, "Electric handsaw"

• Full citation: F. W. Wappat, "Electric handsaw," US 1,830,580, granted Nov. 3, 1931 (filed Aug. 16, 1930), assignor to Wappat, Inc., Pittsburgh, PA.
• Source verified: https://patents.google.com/patent/US1830580
• What it discloses: A rotary (circular) saw, not a hacksaw. Saw frame 1 with handle 2; electric motor 3 with shaft 4 carrying worm 5; transverse shaft 6 with worm wheel 7 and circular saw 8; fixed guard 9 and pivoted telescoping guard 10; adjustable base plate 15 with depth/miter adjustments; a safety switch lever in the handle.
• Claim mapping (§ 102): No anticipation of any of claims 1–4. This is a circular-saw art reference. Its relevance is limited to (a) the general portable electric-saw environment and (b) the handle-integrated switch/safety-lever concept, which is not claimed in US 2,457,829 in any structural detail. Its presence on the citation list appears driven by common-assignee-family/field-of-search considerations rather than by any claimed element.

3.5 US 1,919,323 — Blum, "Saw frame" (likely the frame/blade-mounting reference) [unverified content]

• Full citation: Armstrong Blum Mfg. Co. assignee, "Saw frame," US 1,919,323, granted July 25, 1933 (filed May 27, 1931).
• Claim mapping: The patent's claim 1 recites a "frame for mounting a saw blade or the like," and the specification says the frame must hold a standard hacksaw blade with the bolt at the right-hand end "freely slidable within its bracket" to allow blade tensioning. A Blum "Saw frame" reference is the natural citation for that element. On the metadata alone I can only say it bears on claims 1, 2, 3 and 4 insofar as they each require a saw-blade-mounting frame — but a frame alone cannot anticipate a claim requiring the full drive/hanger/slit combination. I did not read this reference and cannot state what it discloses.

3.6 US 924,509 — Taylor, "Mechanical movement" (candidate source of the endless-spiral-groove mechanism) [unverified content]

• Full citation: W. S. Taylor, Jr., "Mechanical movement," US 924,509, granted June 8, 1909 (filed Apr. 3, 1908).
• Why it matters: The patent's Google classification includes Y10T74/18296 (cam and slide), Y10T74/18304 (axial cam), Y10T74/18312 (grooved) — i.e., the examiner classified this patent's rotary-to-reciprocating mechanism in the grooved-cam art. A "Mechanical movement" patent granted 1909 is the most likely place the examiner found a prior disclosure of a grooved rotary member converting rotation to reciprocation.
• Claim mapping: If (and only if) Taylor discloses an endless/doubled-back spiral groove with a follower, it would bear directly on the "spirally extending guide structure doubled back on itself to provide an endless and returning guide" element common to all four claims — but it would still not anticipate any claim as a whole, because every claim also requires the tubular housing, the slit-crossing hanger, and the low-friction thrust transfer to the housing. Content unverified; I am not asserting it discloses the groove.

3.7 US 1,645,646 — Gray, "Windshield wiper" [unverified content]

• Full citation: W. B. Gray, "Windshield wiper," US 1,645,646, granted Oct. 18, 1927 (filed Feb. 20, 1926).
• Why it matters: A windshield wiper is a classic rotary-to-oscillating/reciprocating motion art. It is the most likely citation for the "swivelly mounted follow member" and/or for converting motor rotation to a back-and-forth stroke.
• Claim mapping: Potentially relevant to the swivel-follower element of claims 1, 2, 3 and 4, but on the metadata alone it cannot anticipate, and the claims each require far more. Content unverified.

3.8 US 1,993,797 — Peterson, "Power unit" [unverified content]

• Full citation: C. E. Peterson, "Power unit," US 1,993,797, granted Mar. 12, 1935 (filed Jan. 14, 1933).
• Claim mapping: A "power unit" reference is plausibly cited for the prime mover + reduction-gearing + housing-to-tool interface that appears in claim 1's "flange means for attaching said tubular elongated housing to the said prime mover." No claim element mapping can be responsibly made without reading it. No anticipation asserted.

3.9 US 699,995 — Whitney, "Engine" [unverified content]

• Full citation: Whitney Motor Wagon Co. assignee, "Engine," US 699,995, granted May 13, 1902 (filed Jan. 13, 1902).
• Claim mapping: An early "Engine" patent, most plausibly cited for a rotary machine element or a grooved/scroll drive. It cannot anticipate any claim of US 2,457,829 on the face of the patent's own disclosure, which is a portable hand hacksaw. Content unverified.

3.10 US 158,932 — Gilbert, "Improvement in hand-pieces of dental engines" [unverified content]

• Full citation: Gilbert, US 158,932, Jan. 19, 1875.
• Why it matters: Dental-engine handpieces of this era are the classic locus of spiral-/scroll-groove drives that convert continuous rotation into a short reciprocating or reversing motion — i.e., the same family as the patent's "endless female thread." This is the oldest reference on the list and the most likely candidate for the idea of the doubled-back groove.
• Claim mapping: At most, if it discloses an endless spiral groove with a follower, it bears on the guide-structure element common to all four claims. It cannot anticipate any claim. Content unverified.

3.11 US 404,017 — Robinson, "Substructure for elevated railways" [unverified content]

• Full citation: Robinson, US 404,017, May 28, 1889.
• Claim mapping: Field-unrelated (railway substructure). Such out-of-field citations are typically mechanical-element references — e.g., a swivel, a grooved guide, a sliding joint, or a flanged-and-ribbed support. Presumably cited for a mechanical detail appearing in the claims (the swivel mount or the flange-joint/brace), not for anticipation of any claim. Content unverified; no anticipation asserted.

3.12 US 436,804 — Roberts [unverified content]

• Full citation: Roberts, US 436,804, Sept. 23, 1890. The patent's own table lists no title (Google's record shows only "roberts"). I could not identify the disclosure. No mapping asserted.

3.13 SE 100,137 — Swedish patent [unverified content]

• Full citation: Swedish Patent 100,137, published Oct. 29, 1940.
• Claim mapping: Listed chronologically between Peterson (1935) and Saucke (1942), which in examiner practice often signals a foreign counterpart of one of the portable-power-tool references. I could not retrieve or read it. No mapping asserted. I note only that it is § 102(a),(b) art by date.

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4. Bottom line on anticipation

No reference cited in US 2,457,829 anticipates any of claims 1–4 under 35 U.S.C. § 102 as a whole. Every one of the four claims is a combination claim requiring, at minimum:

1. an elongated tubular housing; and
2. a drive shaft within it carrying an endless, doubled-back spiral guide; and
3. a hanger projecting from the top of the blade frame into the housing through a slit; and
4. a swivelly mounted follower carried by that hanger; and
5. low-friction means on the hanger reacting thrust into the housing's inner surface.

Claims 1 and 2 additionally require flange means joining housing to prime mover plus a ribbed reinforcing sleeve (claim 1) or the specific two-arm/angularly-lugged guide handle (claims 2 and 4). Claim 3 requires a plurality of spaced-apart hanger members through the slit. Because each cited reference is missing at least the tubular-housing/slit-hanger/endless-groove combination, the citations function as § 103 obviousness evidence, not § 102 anticipation.

Ranking by materiality:

1. Plumb US 2,330,618 — closest overall; portable power hacksaw, motor-driven, blade frame with spaced anti-friction roller pairs transferring load to structure fixed to the motor casing. Directly relevant to the claims-1–4 environment and to claim 3's plural-support idea.
2. Bowen US 1,763,500 — closest on rotary-to-reciprocating conversion in a portable motor housing with a handle and blade coupled to the reciprocating member.
3. Saucke US 2,329,729 — portable motor housing with slide-guided hacksaw frame and rotary-to-reciprocating (chain/link) drive.
4. Gilbert US 158,932 / Taylor US 924,509 / Gray US 1,645,646 — the likely sources for the endless spiral groove and swivel follower concepts (all [unverified content]).
5. Blum US 1,919,323 / Peterson US 1,993,797 — frame and prime-mover-unit elements.
6. Wappat US 1,830,580, Robinson US 404,017, Roberts US 436,804, Whitney US 699,995, SE 100,137 — peripheral/mechanical-element or field-of-search citations.

Best § 103 combinations the examiner likely contemplated:

• Plumb or Saucke (portable motor-driven hacksaw with guided frame) + Gilbert or Taylor (endless/scroll groove converting rotation to reciprocation) + Gray (swivel follower/rotary-to-stroke) → claims 1–4.
• Bowen (rotary cam-in-housing driving a reciprocating blade holder) + Plumb (frame mounted to the motor housing on anti-friction rollers) → claims 1 and 3.

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5. Confidence and limitations

• High confidence on: the composition of the cited-art list, all thirteen citation numbers and their listed dates, the pre-AIA § 102(a)/(b) split (Saucke and Plumb being inside the one-year window), and the full disclosures of Plumb 2,330,618, Saucke 2,329,729, Wappat 1,830,580, and Bowen 1,763,500.
• Low confidence / explicitly not asserted: the disclosures of Gilbert 158,932, Robinson 404,017, Roberts 436,804, Whitney 699,995, Taylor 924,509, Gray 1,645,646, Blum 1,919,323, Peterson 1,993,797, and SE 100,137. I hit my search budget before reading them. Any content characterization above is flagged [unverified] and should not be relied on; I am deliberately not fabricating their teachings.
• Not verified: the actual examiner's reasons for citing each reference (no USPTO file-wrapper/Office-action text was retrieved), and whether any uncited art exists that is closer than the cited art.
• Date discrepancy flagged: this task states April 26, 2026 while the previously generated sections are stamped 2026-10-01. I did not reconcile this; it does not affect the § 102 analysis, which turns on the 1944 filing date.
• Authoritative source used: https://patents.google.com/patent/US2457829/en (full text, reference list, classifications, citation tables).

If you want, the highest-value next step is a targeted read of Taylor 924,509, Gilbert 158,932, and Gray 1,645,646 — those three determine whether the "endless doubled-back spiral guide" limitation was itself old, which is the pivot of the whole § 102/§ 103 question.

I'll pull the prior-art references listed on the patent page and try to get substantive detail on the key ones before doing the § 103 analysis.

Let me pull detail on the remaining cited references, especially the motion-conversion ones.

Obviousness Analysis — US 2,457,829 (35 U.S.C. § 103)

Patent: US 2,457,829 A, "Power-Driven Hand Hacksaw" (indexed title: "Power driven hand racksaw"), Charles D. Miller, filed June 3, 1944, granted Jan. 4, 1949.
Effective date for prior-art purposes: June 3, 1944.
Source for the reference list: the "References Cited" / prior-art section of https://patents.google.com/patent/US2457829/en (12 U.S. patents + Swedish patent 100,137).

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1. Three framing caveats you should hold in view

(a) Statutory timing. § 103 did not exist when this patent was examined. The 1952 Act first codified § 103 (effective Jan. 1, 1953); the 1944–49 examiner applied the pre-1952 "invention" standard of R.S. 4929/4930, under which "invention" connoted something more than non-obviousness. Any § 103 analysis of this patent is therefore retrospective and counterfactual, and post-KSR doctrine makes the analysis materially more expansive than what the examiner would have applied. Read the conclusions below as "would this have survived a modern § 103 challenge," not as a criticism of the 1949 grant.

(b) Evidence quality. I verified content only for four references (Plumb, Saucke, Wappat, Bowen — see §3). For Taylor 924,509, Gray 1,645,646, Blum 1,919,323, Peterson 1,993,797, Whitney 699,995, Roberts 436,804, Robinson 404,017, Gilbert 158,932 and Swedish 100,137, I have only the title/date/assignee metadata from the patent page — my tool calls were cut off before I could pull their texts. Where I characterize their content I label it as inference. Do not treat those characterizations as verified.

(c) Practical stakes. Per the litigation section already generated, this patent expired Jan. 4, 1966 and appears in no indexed litigation. A § 103 holding here has no current validity consequence; it matters for (i) historical completeness and (ii) characterizing the patent as § 102/§ 103 prior art against later filings.

Also note: the "Cited By" table (Olson 2,668,567; Farkas 4,505,037; Commonwealth of Puerto Rico 5,313,709; Van Camp 6,256,891; Callne 6,925,719 / 2005/0115085; Black & Decker 9,701,032 and 12,011,820) is post-1949 and cannot be § 102/§ 103 prior art against this patent. It is relevant only to the mirror-image question — whether this patent anticipates or renders obvious those later filings.

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2. Person of ordinary skill in the art (PHOSITA), as of June 1944

A mechanical designer/engineer with roughly 2–5 years' experience in portable electric hand-tool development, holding at minimum a technical high-school or apprenticeship background, familiar with: small AC/DC universal motors, single-stage and multi-stage reduction gearing, worm and chain drives, and the standard catalogue of rotary-to-reciprocating conversions (crank-and-connecting-rod, Scotch yoke, Whitworth quick-return, swash plate, and screw/axial-cam drives). He is a routine consumer of the patent literature — the near-simultaneity of Plumb, Saucke and Miller (see §6) is itself evidence that a small, identifiable group was working this exact problem.

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3. Element mapping against the verified references

The gap is narrow and it is confined to the motion-conversion package: an endless, doubled-back spiral groove on a rotating drive shaft, a swivel follower riding it, and a blade frame suspended by a hanger through a slit in a tubular housing with the shaft acting as both the drive member and the frame's bearing support. Everything else on claims 1, 2 and 4 — motor, reduction gearing, reciprocated blade frame, low-friction thrust transfer to the housing, handles — is taught squarely by Plumb and Saucke.

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4. The single most damaging fact for the patent: the patentee's own admission

The specification states, in terms:

"Such a grooved endless thread has been known previously as a mechanism capable of converting a continuous rotational movement in a single direction into a reciprocatory or back and forth motion."

This is an express admission that the core inventive element of every claim (the "spirally extending guide structure doubled back on itself") is old. It is binding on the patentee in the way all specification admissions are. Once the conversion element is conceded to be old, claims 1–4 reduce to the question of whether it was obvious to substitute a known conversion mechanism for the crank/chain/cam mechanisms that Plumb, Saucke and Bowen already used — which is precisely the fact pattern KSR addressed.

The examiner's own classification supports this: Google Patents indexes this patent in Y10T74/18296 (cam and slide), Y10T74/18304 (axial cam), Y10T74/18312 (grooved) and Y10T83/8843 (cam or eccentric revolving about fixed axis). The Office treated the drive as an old cam type, not a novel motion.

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5. Grounds of rejection

Ground A — the primary case: Claim 1 obvious over Plumb in view of Saucke, further in view of the "mechanical movement" art

1. Plumb teaches every mechanical system element of claim 1 except the spiral-groove drive, the slit-and-hanger mounting, and the ribbed flange sleeve: portable electric hacksaw, motor + reduction gearing, reciprocated blade frame, rollers (21/22) riding rails to take thrust, and a bar-grip handle.
2. Saucke supplies the "portable cutting tool with a motor, a reciprocating slide, and a blade frame" template and, importantly, shows an alternative known drive (chain + pivoted link) — reinforcing that the drive mechanism was a recognized design variable.
3. The spiral-groove drive is either (i) admitted old by the patentee, or (ii) disclosed in the reference(s) cited by the examiner for that element — most plausibly Taylor 924,509 ("Mechanical movement," 1909) and/or Gray 1,645,646 ("Windshield wiper," 1927), both of which sit in the cam/slide and screw-conversion families, and in the case of the windshield-wiper art, were contemporaneous with the well-known reversing-screw wiper drives. Caveat: I could not verify the subject matter of either reference; this sub-point is inference from title and from the examiner's choice to cite them, and should be confirmed against the documents before being asserted as fact. Bowen 1,763,500 independently confirms that a portable motor-driven saw in which a rotary member (cam drum 13) converts motor rotation to reciprocating blade motion was known and commercially acceptable.

Motivation to combine (why PHOSITA would do it):

• The patent's own stated problem defines the motivation. The specification's background recites that prior power-driven hand hacksaws "have not been highly successful ... for various reasons including faults attributable primarily to their drive mechanism," because they "either employed a considerably restricted stroke or else have been rendered awkward and cumbersome by the incorporation of bulky parts to provide a more satisfactory stroke." A crank-and-link (Plumb) and a chain-and-link (Saucke) both require lateral space and produce a stroke limited by crank radius or chain length. A coaxial screw-groove drive yields a long stroke within the diameter of the drive shaft and removes rod/crank side-loading. The patent's own objectives (long stroke "comparable in length to the normal stroke in manual operation," and "substantially constant" stroke speed) are the direct, predictable results of that substitution. That is a finite, identified, predictable solution set — KSR at 421.
• Result-predictability / reasonable expectation of success. Substituting one known rotary-to-reciprocating converter for another in a portable saw, without change to the motor, gearing, frame, or blade, is the paradigm of a predictable substitution of known elements performing their known functions. There is no unexpected result alleged for the conversion itself.
• § 102(e) timing. Both Plumb and Saucke were filed (July 14, 1941; May 4, 1942) before Miller's June 3, 1944 filing and issued before it. They are therefore prior art under pre-AIA § 102(a) and § 102(e), and available for § 103 combination.
• Rebuttal note: because the substituted element is admitted old, the patentee cannot fall back on "the mechanism itself was new." The only available nexus argument is the combination — and the combination's only novel structural consequences (the hanger-through-slit suspension and the shaft serving as the frame's bearing) are separately addressed below.

Ground B — the hanger/slit/roller sub-combination (claims 1, 2, 3) obvious over Plumb

Plumb's rollers 21, 22 are journaled on axles on the frame and "ride in elongated slots 23 and 24 formed in guide bars 25 and 26 ... disposed one at either side of the frame." That is functionally the same thrust-transfer arrangement claimed: a low-friction anti-friction element on the frame member riding fixed structure to absorb the cutting reaction. Saucke equally shows a slide 16 captured between two guide rails 15.

Motivating the shift to a slit-and-hanger arrangement (aperture in a tubular housing rather than external rails) is obvious on ordinary design grounds: enclosing the moving interface in the housing (i) protects the sliding surfaces from chips and coolant — a stated concern of this tool class — and (ii) lets a single tubular housing serve simultaneously as the structural beam, the drive-shaft bearing carrier, and the guide. A housing with a long slit to pass a reciprocating member is the conventional way to enclose a linear motion. Claim 3's "plurality of spaced apart hanger members" is likewise obvious over Plumb's two spaced apart pairs of rollers and Saucke's elongated slide, since distributing two supports along a reciprocating member to prevent cocking is a known expedient.

Ground C — the guide handle (claims 2 and 4) obvious over Plumb and Saucke in view of 1944 hand-tool design practice

Claim 2's handle is a two-arm bracket — one arm at ~normal, one at less than 90°, ends offset to opposite sides, with angularly disposed mounting lugs. Plumb already discloses two handles (33 on the motor axis, 35 as a second grip), and Saucke discloses handles 12, 13 — i.e., plural-handle, two-point-control of a portable power saw was standard.

Two independent reasons this does not save claims 2 or 4:

1. The specification concedes this is a matter of operator preference, not a technical problem. The patent states the handle "is adapted to be formed of a single piece of either solid or hollow bar stock to rest against the outer top portion of hacksaw frame," that some operators grip it with the hand and fingers while others use it as a palm abutment, and that it is "so shaped that it may be employed in either manner and is thus adapted to the use of any individual regardless of his practice in this regard." Under § 103, "[t]he same is true of a change made to accommodate a known need or preference of a user" — accommodating two known operator habits with one bracket is the definition of obvious subject matter, and the "single piece of bar stock" is a weight/parts-count economy that the specification elsewhere claims as an object (light weight, few parts).
2. Claim 4 is claim 2 with the "less than 90°" angle deleted — i.e., an even broader bracket. If claim 2 falls, claim 4's broader scope is a fortiori not inventive; and the lugs are "angularly disposed ... fastening lugs," conventional bracket feet.

Ground D — the ribbed reinforcing sleeve (claim 1, final element)

Securing a tubular member to a flange plate and welding or riveting a ribbed gusset over the tube-to-flange junction to raise bending stiffness is textbook machine design. The patent does not allege any unexpected property for the rib configuration, and the object it serves ("sufficient strength and rigidity in the housing") is a generic structural desideratum. I found no reference in the cited set specifically directed to a ribbed brace, but that is not helpful to the patentee: where a claimed structure is a predictable, conventional mechanical expedient serving a known function, the absence of a specific reference is not a defense post-KSR (the KSR "design incentives" / "common sense" line). This element is the patent's weakest defense and its strongest candidate for a "routine design choice" rejection. Note also that Robinson 404,017 ("Substructure for elevated railways," 1889) is the kind of reference examiners cite precisely for flange-and-rib frame-bracing structure; I could not verify its content and flag this as an untested hypothesis.

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6. Secondary / objective considerations (Graham factors)

Mostly adverse to the patent, on the present record:

• Long-felt but unmet need? The specification asserts prior power hand hacksaws were commercially unsuccessful. That is a statement of a known problem, which supports the existence of a long-felt need but also proves the problem was recognized and that the field was actively working it — the setup for obviousness, not away from it.
• Simultaneous independent invention — the strongest objective evidence AGAINST validity. Saucke filed May 4, 1942; Plumb filed July 14, 1941; Miller filed June 3, 1944. Three separate workers reached the "motorized hand hacksaw with a reciprocating blade frame and a compact reduction drive" in a three-year window. That is the classic indicator that the art had reached the point where the result was "the work of the ordinary mechanic."
• No unexpected results pleaded. The specification asserts functional advantages (stroke length, constant stroke speed, light weight, use of standard blades, manual-start capability). Those are designed-in objectives, recited ex ante as the inventor's goals — which is the opposite of In re Soni-style unexpected results. Notably the patent does not claim a surprising or superior result from the spiral-groove drive; it claims it as a convenient accommodation.
• No commercial-success or licensing evidence of record; assignee is "Individual," with no assignment data I could verify from an authoritative USPTO source (the Google Patents notice itself states its assignee/legal-status fields are assumptions). The government-license clause ("Granted under the act of March 3, 1883, as amended") is consistent with a non-commercialized government-interest patent. No nexus evidence exists to argue.
• Copying? No evidence located.

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7. Bottom line

Overall: on the prior art cited on the face of the patent, claims 1–4 would very likely be held obvious under a modern § 103 analysis. The linchpin is the patentee's express admission that the endless grooved screw is an old rotary-to-reciprocating converter, combined with Plumb and Saucke, both of which are pre-filing-and-pre-issuance § 102(a)/(e) art describing portable electric hacksaws with motor, reduction gearing, reciprocated blade frames and anti-friction means for reacting blade thrust into the housing.

Where I would want more before testifying to this:

1. The full texts of Taylor 924,509, Gray 1,645,646, Blum 1,919,323 and Swedish 100,137 — the screw/cam-family references, which determine whether the primary drive element is disclosed rather than merely admitted old. (My searches for these returned no substantive content before tool limit; I did not verify them.)
2. Peterson 1,993,797 ("Power unit") and Wappat 1,830,580 — likely cited for the motor/reduction-gear/handle sub-combination.
3. Confirmation of the pre-1952 "invention" standard as actually applied by the examiner, if the goal is to explain the 1949 grant rather than to assess modern validity.
4. Swedish 100,137 (1940) — foreign art as of Oct. 29, 1940, well before the filing date; if it discloses a screw-groove reciprocator for a saw, it strengthens Ground A considerably. I could not retrieve it.

One contradiction to flag between this section and the earlier ones: the earlier summary describes the motion-conversion element as the "core inventive concept." That is a correct reading of how the patent claims, but it is in tension with the specification's own admission that the grooved endless thread "has been known previously." Both statements are accurate about different things — what the applicant claimed versus what the applicant conceded — but they should not be quoted together without that explanation, since the concession is what drives this § 103 result.