CIRCULAR SAW BLADE GUARD

• US 3,754,493 A
• Filed: 12/10/1971
• Issued: 08/28/1973
• Est. Priority Date: 12/10/1971
• Status: Expired due to Term

• Current Assignee: Delta International Machinery Corp. (Stanley Black & Decker, Inc.)
• Original Assignee: Edward J. Niehaus, Harry D. Benney
• Inventors: Niehaus, Edward J., Benney, Harry D.
• Primary Examiner(s): Schran, Donald R.
• Application Number:
  US05/206,630
• Time in Patent Office: 627 Days
• Field of Search: 143/159J,159T,159R 144/251R 83/478,477.2,477.1,477,508.2 30/390,391
• US Class Current: 83/478
• CPC Class Codes: B27G 19/02 for circular saws
• CPC Class Codes: Y10T 83/7734 With guard for tool
• CPC Class Codes: Y10T 83/7872 Tool element mounted for adjustment

Abstract

A see through plastic U-shaped circular saw blade guard and kerf splitter assembly wherein the guard is pivotally swingably mounted on the kerf splitter through a relatively short inverted U-shaped link pivoted at one end in straddling relation to the kerf splitter with the web at the one end notched out to dispose the notch end wall to engage the upper edge of the kerf splitter and limit its upward and rearward pivotal movement to maintain the link and guard pivoted at the other end in straddling relation to the link within the upper foreward segment of the pivotal path of the link at all times to assure weight biased movement toward the saw table and guarding position. The kerf splitter is a plate of generally C-shaped configuration having attachment bolt passages in the foreward and rear ends of the lower arm to provide at least one attachment bolt beneath and foreward of the rear end of the table in a relatively inaccessible position when installed to prevent ready removal by the operator. The respective pivot connections include pivot pins fixedly connected to the link and fixedly connected to the guard respectively by end mounted press fitted washers and cap nuts to prevent ready disassembly of the pivot connections and removal of the link or guard. The assembly provides a non-removable safety guard.

Claims

1. A safety blade guard for table type circular saws having a work support table providing an elongated blade passage and a motor driven saw blade arranged for depth of cut adjustment through the blade passage at varying angular adjustments relative to the plane of the table work support surface comprising a support bracket fixedly secured relative to the saw blade beneath the table and having a plate-like portion extending rearwardly beyond the rear edge of the work support table, a kerf splitter plate fixedly secured to said support bracket at a relatively inaccessible point beneath the rear edge of the table and including an upwardly and forwardly directed portion disposed to overlie the table in the plane of rotation of the saw blade at the rear of the saw blade and terminating at its forward end in an arcuate portion overhanging in radially spaced relation the rear segment of the blade exposed through the blade passage;

link means pivotally connected at one end to said portion of said kerf splitter inwardly from its forward end for limited swinging movement around an axis disposed at right angles to the plane of rotation of the blade between a forwardly extending guarding position overhanging the exposed blade and an upwardly and forwardly inclined guarding position overhanging the exposed blade, said pivot connection including pivot means non-removably fixed to said kerf splitter with its opposite ends projecting laterally therefrom to fixedly receive said link means; and

an inverted U-shaped, elongated blade guard pivotally suspended from the other end of said link means in straddling relation to said pivot connection and the exposed portion of said saw blade in all swing positions of said blade guard, said pivotal suspension including a pivot pin non-removably fixed to said blade guard whereby a blade guard normally biased to operative blade guarding position on the work support table and incapable of being readily removed or swung to an inoperative position is assured.

2. The safety blade guard assembly of claim 1 wherein the blade guard rear end beyond said link pivot connection engages the upper edge of said kerf splitter preventing independent pivotal movement of said blade guard upwardly and rearwardly and the forward ends of said blade guard side walls extend forwardly of said exposed blade portion and are upwardly and forwardly inclined to provide camming surfaces engageable with the leading upper corner of a workpiece fed into the saw blade to pivot the blade guard and link means upwardly and rearwardly as a unit around the axis of the pivot connection to the kerf splitter until the leading upper corner of the workpiece reaches a position immediately forward of said pivotal suspension thereby permitting rapid retrograde pivotal movement of said blade guard around said pivotal suspension into bearing engagement with the upper surface of the workpiece in straddling relation to the developing saw kerf in the workpiece to guard the blade emerging through the workpiece.

3. The safety blade guard of claim 1 wherein the depending blade guard sidewall adjacent the blade face forming the acute angle with the table work support surface at the varying angular adjustments is vertically foreshortened relative to the opposite blade guard sidewall whereby said foreshortened sidewall is maintained out of contact with said work support table thereby eliminating side thrust forces on the blade guard when angular adjustments are effected to bevel cut workpieces.

4. The safety blade guard of claims 1 and 2 wherein the blade guard is formed of distinctively colored see through plastic to serve as a constant visual warning of the danger zone created by the expoded saw blade portion while permitting a clear view of the cutting action.

5. The safety blade guard of claim 1 wherein said kerf splitter is through apertured and bushed to journal said first pivot pin and said link means comprises a short, rigid metal, inverted channel member having respective axially aligned pairs of passages formed in the adjacently related sidewalls at one end to fixedly receive said first pivot pin thereby relegating pivotal wear to the bushing of said kerf splitter and the portions of the pivot pin enclosed thereby whereby canting forces applied to the blade guard during use of the saw will be torsionally resisted by said link means.

6. The safety blade guard of claim 5 wherein said bushing comprises a metal bushing having a center portion fitted to said kerf splitter through aperture, opposite end faces spaced apart to have light bearing engagement with the opposing areas of the adjacently related inner faces of the sidewalls of said channel member, and a centered longitudinal through bore coaxially related to the aligned pair of passages in said channel member one end.

7. The safety blade guard of claim 6 wherein the periphery of said metal bushing adjacent the opposite kerf splitter side faces is reduced in diameter to form a first pair of annular steps and the opposite ends are further reduced in diameter to form respective annular journals;

respective anti-kickback fingers are journalled on said annular journals; and

a torsion biasing spring is provided comprising a pair of axially spaced coils respectively encircling said first pair of annular steps with their adjacent ends interconnected in spanning relation to the upper edge of said kerf splitter and their outer ends drive connected to said anti-kickback fingers to bias them to dependent operative position, thereby forming a captive anti-kickback assembly.

8. The safety blade guard of claim 1 wherein said blade guard has dependent sidewalls which are inwardly thickened and coaxially through apertured at opposed points rearwardly offset from its longitudinal center to closely but freely receive said links means, said pivotal suspension includes a pivot pin fixedly carried in said blade guard side walls and journalling said link means, and said link means comprises a short rigid metal channel member having respective axially aligned pairs of journal passages formed in the adjacently related sidewall ends to journallingly receive said pivot pin of said pivot connection relegating pivotal wear to the link means and the portions of the pivot pin enclosed thereby and providing spaced bearings surfaces whereby canting forces applied to the blade guard during use of the saw will be torsionally resisted by said link means.

9. The safety blade guard of claim 8 wherein said pivot means comprises a headed pin having its head disposed in face butted engagement with one sidewall of said blade guard and a shank protruding through and beyond the opposite sidewall of said blade guard and a cap nut drive fitted to the protruding end of said pin shank into end butting engagement with the opposing blade guard sidewall operative to obviate ready removal of said headed pivot pin.

10. A splitter and safety blade guard assembly for a table type circular saw having a mounting bracket disposed below the rear table edge in fixed relation to the saw blade comprising a generally C-shaped splitter blade the lower arm of which is fixedly secured to said mounting bracket and the upper arm of which extends forewardly from the rear table edge in the plane of rotation of said sAw blade to a point forewardly of a vertical plane containing the rotational axis of the saw blade, said splitter blade upper arm defining an arcuate knife edge disposed in radially spaced overlying relation to the rear segment of the exposed saw blade and having a laterally directed through passage adjacently related to its upper edge in a vertical plane offset rearwardly from its front end a distance less than half the longitudinal distance between the opposite ends of said knife edge;

a journal bushing fixedly supported in said splitter blade passage with its opposite ends projecting equidistantly beyond the opposite faces of said splitter blade;

an inverted, U-shaped, elongated blade guard disposed in straddling relation to said portion of said splitter blade defining said arcuate knife edge and the front segment of the exposed saw blade, said blade guard rearwardly of its longitudinal center and adjacent its connecting web being provided with inwardly thickened, laterally spaced lands having respective laterally aligned through passages therein;

a rigid channel shaped guard mounting link having dependent sidewalls the respective ends of which are spaced to receive and have bearing contact with said ends of said beushing and to be received between and having bearing contact with said lands of said guard and respective pairs of aligned through passages in said respective ends;

a first pivot pin extending through said bushing and the cooperating aligned passages of said one link end and dimensioned to provide a pivotal fit with said bushing and fixed fit with said one link end; and

a second headed pivot pin having a shank extending through said aligned guard passages and the cooperating aligned passages of said other link end, said shank being dimensioned to provide a fixed fit with said guard and a pivotal fit with said link.

11. The splitter and safety guard assembly of claim 10 wherein said headed pivot pin is positioned to establish a face butting engagement with one guard side wall and has a shank of sufficient length to protrude beyond said other guard wall and a cap nut is press fitted onto the protruding shank end into face butting engagement with the other guard side wall to thereby prevent the headed pivot pin from being driven out to effect removal of the guard.

12. The splitter and safety guard assembly of claim 10 wherein said first pivot pin is of a length to assure protrusion of its opposite ends beyond the opposite side wall of said link and respective spring washers are press fitted on the opposed pin ends into face bearing contact with the opposite side walls of said link to thereby prevent the first pivot pin from being driven out to effect removal of said link.

13. The splitter and safety guard of claim 10 wherein the connecting link at said one link end is inwardly notched relative to the sidewall ends to provide an end abutment face adapted to abuttingly engage the upper edge of the splitter blade in relative pivotal movement of said link and bushing to limit the upward and backward swinging movement of said link to prevent the guard from being swung to an inoperative guarding position.

14. The splitter and guard assembly of claim 10 wherein said bushing between said link sidewalls is stepped to provide first and second pairs of annular journals, respective anti-kickback fingers are journalled on said first pair of journals in dependent relation to operatively cooperate with the upper surface of a workpiece at opposite sides of the developing saw kerf to prevent the workpiece and the severed segments of the workpiece from being kicked out of the saw by the rotating blade during a sawing operation and a double coil spring having an interconnecting bridging run engaging the upper edge of said splitter blade and respective hooked outer ends engaging said anti-kickback fingers has its coils mounted on said second pair of journals whereby said spring will be tensioned by rearward swinging movement of said anti-kickback fingers upon feeding a workpieCe into the saw and against the kickback fingers to forcefully engage the kickback fingers with the workpiece during the sawing operation.