Patent US3721141A successfully refreshed from Google Patents.
US3721141A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Movable blade guard and mounting for portable circular saws
Assignee: Porter Cable Corp
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Filing: 1971-07-06
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Granted: 1973-03-20
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Expires: 1991-07-06
Abstract
Abstract A movable guard and mounting for portable motor driven circular saws in which the movable guard is directly journalled on the blade arbor shaft through an end thrust resisting antifriction bearing means arranged to isolate the movable guard from the rotational forces of the arbor shaft and accommodate the side thrust forces transmitted to the movable guard in use during its retractile movement effected by abutting engagement with the workpiece. The antifriction bearing means, being directly carried by the blade arbor shaft, is of minimal diameter permitting its installation well within the normal centrifugal discharge path of the chips and sawdust defined by the peripheral blade enclose lips of the fixed and movable guard in closely adjacent relation to the cutter blade mounting to form a labyrinth passage with the cutter blade mounting excluding entry of chips and sawdust.
Inventors
- 👤 L Frostad
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 12:59
CPC Classifications
B; B27; B27B; B27B9/00; B27B9/02; B27G; B27G19/00; B27G19/02; B27G19/025; B27G19/04
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
254 words
In a portable power driven circular saw conventionally providing a motor housing, motor means including a blade arbor shaft projecting outwardly from one end of said motor housing and mounting a cutter blade on its free end, a base adjustably suspended from the housing for guiding said blade along the workpiece and adjusting the cutter blade with respect to the work to effect bevel cutting, and stationary guard means fixed to the one housing end in partial surrounding relation to the cutter blade: an improved movable guard and mounting for directly mounting said movable guard on said cutter blade arbor shaft comprising a movable guard disposed to normally surround the remainder of the cutter blade and arranged for telescoping retraction at least partially within said fixed guard upon engagement with the workpiece, means biasing said movable guard to its normal extended cutter blade surrounding position, and mounting means for said movable guard journalling said movable guard on said blade arbor shaft for arcuate movement between its normal extended position and retracted position comprising end thrust resisting antifriction bearing means encircling said arbor shaft free end inwardly of said cutter blade and means mounting said movable guard on said bearing means, said movable guard normally being isolated by said bearing means from the rotational forces of said blade arbor shaft tending to move said movable guard to its normal extended position thereby facilitating movement of said movable guard from its normal extended position with minimum effort upon engagement of said movable guard with the workpiece.
Claim 2
Dependent Claim
254 words
In a portable power driven circular saw conventionally providing a motor housing, motor means including a blade arbor shaft projecting outwardly from one end of said motor housing and mounting a cutter blade on its free end, a base adjustably suspended from the housing for guiding said blade along the workpiece and adjusting the cutter blade with respect to the work to effect bevel cutting, and stationary guard means fixed to the one housing end in partial surrounding relation to the cutter blade: an improved movable guard and mounting for directly mounting said movable guard on said cutter blade arbor shaft comprising a movable guard disposed to normally surround the remainder of the cutter blade and arranged for telescoping retraction at least partially within said fixed guard upon engagement with the workpiece, means biasing said movable guard to its normal extended cutter blade surrounding position, and mounting means for said movable guard journalling said movable guard on said blade arbor shaft for arcuate movement between its normal extended position and retracted position comprising end thrust resisting antifriction bearing means encircling said arbor shaft free end inwardly of said cutter blade and means mounting said movable guard on said bearing means, said movable guard normally being isolated by said bearing means from the rotational forces of said blade arbor shaft tending to move said movable guard to its normal extended position thereby facilitating movement of said movable guard from its normal extended position with minimum effort upon engagement of said movable guard with the workpiece.
Claim 3
Dependent Claim
84 words
The movable guard and mounting of claim 1 wherein said end thrust resisting antifriction bearing means comprises a bearing having an inner race directly encircling said blade arbor shaft so as to rotate with said blade arbor shaft and an outer race directly mounting said movable guard so said movable guard will be freely rotate from its extended position relative to said inner race and blade arbor shaft under influence of its engagement with the workpiece as said saw is guided along the workpiece.
Claim 4
Dependent Claim
84 words
The movable guard and mounting of claim 1 wherein said end thrust resisting antifriction bearing means comprises a roller bearing having an inner race directly encircling said blade arbor shaft so as to rotate with said blade arbor shaft and an outer race directly mounting said movable guard so said movable guard will freely rotate from its extended position relative to said inner race and blade arbor shaft under influence of its engagement with the workpiece as said saw is guided along the workpiece.
Claim 5
Dependent Claim
179 words
The movable guard and mounting of claim 2 wherein said movable guard is formed with a hub portion having a through stepped bore coaxially disposed with respect to said blade arbor shaft with its major diameter bore portion at its distal end and dimensioned to closely receive said outer race of said end thrust resisting antifriction bearing means with one end of said outer race in end abutted relation to the axially facing shoulder defined by said stepped bore and formed inwardly from its distal end with an inwardly opening annular ring groove located in juxtaposition to said other end of said outer race, and a snap ring supported in said annular ring groove in overlapping relation to the marginal portion of said other end of said outer race whereby side thrust forces applied to said movable guard due to engagement of said movable guard and workpiece in making bevel cuts and angle cuts of said workpiece and resisted by said antifriction bearing means thereby enabling the operator to accurately cut along a scribed line applied to said workpiece.
Claim 6
Dependent Claim
68 words
The movable guard and mounting of claim 4 wherein said biasing means comprises tensioned spring means disposed in surrounding relation to said movable guard hub portion having its Opposite ends respectively anchored to said movable guard and to a fixedly related portion of said saw whereby the sole force to be overcome in retractile movement of said movable guard is the biasing force of said tensioned spring means.
Claim 7
Dependent Claim
129 words
The movable guard and mounting of claim 1 wherein said end thrust antifriction bearing means is press fitted on said arbor shaft immediately adjacent the mounting for said cutter blade and said movable guard includes a wall portion adjacently related to said cutter blade mounting and formed on the face remote from said cutter blade mounting with a hub providing a stepped bore defining a seat for said antifriction bearing means delimited in the plane of said wall portion by an inwardly directed annular abutment shoulder which partially overlaps said cutter blade mounting in close radially spaced relation to form therewith a labyrinth passage which, due to the high speed rotation of said cutter blade mounting, substantially negates the possibility of chips and sawdust entering said antifriction bearing means.
References Cited (Backward Citations)
US3177909A
Cited
US3292673A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-03-19 | 1976-09-18 | 1977-03-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-03-19 | 1980-09-18 | 1981-03-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-03-19 | 1984-09-18 | 1985-03-20 | $7700.00 | Window Closed / Lapsed |