Circular cutter

Claim 2

A work piece holder and guard for a circular cutter having a rotary beam bearing a downwardly extending cutting knife, said beam being mounted transversely on a shaft attachable to a rotary chuck that can move axially to advance and retract said cutter relative to a work piece and can rotate said cutter relative to said work piece for making a circular cut, said work piece holder and guard comprising: a. a transparent guard drum having a generally cylindrical wall surrounding and enclosing the rotational path of said beam; b. said drum having a transparent top rotatably mounted on said shaft above said beam and enclosing a region between said shaft and an upper region of said cylindrical wall; c. a transparent, annular pressure shoe removably secured to a lower region of said cylindrical wall and extending below said beam in a plane parallel with said work piece radially inward from said cylindrical wall to a central opening in said pressure shoe through which said cutting knife can advance; and d. a spring axially biasing said drum downward on said shaft relative to said beam so that said drum and said pressure shoe move up and down with said chuck and said beam throughout a region wherein said pressure shoe moves clear of said work piece, and said spring is compressed throughout a region of axial movement of said chuck and said beam wherein said pressure shoe engages and holds said work piece in place and said cutting knife advances into cutting engagement with said work piece while guarded by said drum.

Claim 3

The holder and guard of claim 1 including a plurality of said pressure shoes interchangeably mountable on said drum and having said central opening in different sizes to accommodate different diameter cuts.

Claim 4

The holder and guard of claim 2 including a quick connect and disconnect mounting for said pressure shoes on said drum.

Claim 5

The holder and guard of claim 3 wherein said quick connect and disconnect mounting includes screws on said drum and keyhole slots in said pressure shoes engageable by heads of said screws.

Claim 6

The holder and guard of claim 1 including a collar fixed on said shaft above said drum and a bearing between said drum and said shaft, and said spring is a compression spring around said shaft between said collar and said bearing.

Claim 7

The holder and guard of claim 5 including a thrust bearing between said spring and said drum.

Claim 8

The holder and guard of claim 1 wherein said beam is a single piece secured to said shaft and having a channel opening downward along a bottom region of said beam, a pair of knife blocks are fitted accurately within said channel for moving to radially adjustable positions along said channel, sides of said channel and said knife blocks have mating ridges and grooves, and each of said knife blocks carries one of said cutting knives.

Claim 9

The holder and guard of claim 7 including a collar fixed on said shaft above said drum and a bearing between said drum and said shaft, a thrust bearing between said spring and said drum, and said spring is a compression spring around said shaft between said collar and said bearing.

Claim 10

The holder and guard of claim 8 including a plurality of said pressure shoes interchangeably mountable on said drum and having said central opening in different sizes to accommodate different diameter cuts and including a quick connect and disconnect mounting for said pressure shoes on said drum.

Claim 11

In a circular cutter for use in a machine having a rotatable chuck that is movable axially, said circular cutter having a drive shaft attachable to said chuck for turning a beam mounted transversely of said shaft and bearing a radially adjustable cutter knife, the improvement comprising: a. a guard drum rotationally mounted on said shaft above said beam to extend radially outward from said shaft over said beam and downward in a generally cylindrical wall surrounding the rotational path of said beam; b. said guard drum being formed of transparent material allowing an operator to see through said drum for observing said cutter, and said guard drum being substantially closed from said shaft to a bottom region of said cylindrical wall to keep an operator's fingers away from said beam when said beam is turning within said drum; c. an annular, transparent pressure shoe removably secured to said bottom region of said cylindrical wall to lie in a plane below said beam and to extend radially inward from said cylindrical wall to a central opening of said pressure shoe within which said cutter knife can turn; and d. a stop, a spring, and a thrust bearing arranged for urging said drum downward relative to said shaft and said beam so that said drum and said pressure shoe move with said chuck and said beam throughout a region clear of said work piece, and while said pressure shoe engages and holds said work piece, said chuck can advance said beam toward said work piece by compression said spring and can rotate said beam against said work piece within said opening in said pressure shoe to make a circular cut.

Claim 12

In a circular cutter for use in a machine having a rotatable chuck that is movable axially, said circular cutter having a drive shaft attachable to said chuck for turning a beam mounted transversely of said shaft and bearing a radially adjustable cutter knife, the improvement comprising: a. a guard drum rotationally mounted on said shaft above said beam to extend radially outward from said shaft over said beam and downward in a generally cylindrical wall surrounding the rotational path of said beam; b. said guard drum being formed of transparent material allowing an operator to see through said drum for observing said cutter, and said guard drum being substantially closed from said shaft to a bottom region of said cylindrical wall to keep an operator's fingers away from said beam when said beam is turning within said drum; c. an annular, transparent pressure shoe removably secured to said bottom region of said cylindrical wall to lie in a plane below said beam and to extend radially inward from said cylindrical wall to a central opening of said pressure shoe within which said cutter knife can turn; and d. a stop, a spring, and a thrust bearing arranged for urging said drum downward relative to said shaft and said beam so that said drum and said pressure shoe move with said chuck and said beam throughout a region clear of said work piece, and while said pressure shoe engages and holds said work piece, said chuck can advance said beam toward said work piece by compression said spring and can rotate said beam against said work piece within said opening in said pressure shoe to make a circular cut.

Claim 13

The improvement of claim 10 wherein said beam is a single piece secured to said shaft and having a channel opening downward along a bottom region of said beam; a pair of knife blocks, each bearing one of said cutter knives, are fitted accurately within said channel for moving to radially adjustable positions along said channel; and said sides of said channels and said knife blocks have mating ridges and grooves.

Claim 14

The improvement of claim 10 including a plurality of said pressure shoes interchangeably mountable on said drum and having said central opening in different sizes to accommodate different diameter cuts.

Claim 15

The improvement of claim 12 including a quick connect and disconnect mounting for said pressure shoes on said drum.

Claim 16

The improvement of claim 13 wherein said quick connect and disconnect mounting includes screws on said drum and keyhole slots in said pressure shoes engageable by heads of said screws.

Claim 17

The improvement of claim 14 wherein said beam is a single piece secured to said shaft and having a channel opening downward along a bottom region of said beam; a pair of knife blocks, each bearing one of said cutter knives, are fitted accurately within said channel for moving to radially adjustable positions along said channel; and said sides of said channels and knife blocks have mating ridges and grooves.

Claim 18

In a circular cutter having a shaft rotating a beam carrying a pair of radially adjustable cutter knives, the improvement comprising: a. said beam being a single piece of steel secured to said shaft and having closed sides and top and a channel oriented to open downward along a bottom of said beam; b. a pair of knife blocks movable radially in said channel and bearing said knives to extend below said beam, said knife blocks and said channel having mating ridges and grooves extending along opposite sides of said channel; and c. a transparent guard drum mounted on said shaft for rotational and vertical movement relative to said beam, said guard drum being shaped for extending outward above said beam to a generally cylindrical wall surrounding the rotational path of said beam and extending down to engagement with a work piece being cut by said knives.

Claim 19

In a circular cutter having a shaft rotating a beam carrying a pair of radially adjustable cutter knives, the improvement comprising: a. said beam being a single piece of steel secured to said shaft and having closed sides and top and a channel oriented to open downward along a bottom of said beam; b. a pair of knife blocks movable radially in said channel and bearing said knives to extend below said beam, said knife blocks and said channel having mating ridges and grooves extending along opposite sides of said channel; and c. a transparent guard drum mounted on said shaft for rotational and vertical movement relative to said beam, said guard drum being shaped for extending outward above said beam to a generally cylindrical wall surrounding the rotational path of said beam and extending down to engagement with a work piece being cut by said knives.

Claim 20

The improvement of claim 16 including a collar fixed on said shaft above said drum, a bearing between said drum and said shaft, and a compression spring around said shaft between said collar and said bearing for biasing said drum downward relative to said beam.

Claim 21

The improvement of claim 17 wherein said bearing includes a thrust bearing.

Claim 22

The improvement of claim 17 including an annular pressure shoe removably attached to a bottom region of said guard drum to extend radially inward below said beam to a central opening in said pressure shoe closely surrounding a cut made by the outermost one of said knives.

Claim 23

The improvement of claim 19 including a plurality of said pressure shoes interchangeably mountable on said guard drum and having said central opening in different sizes to accommodate different diameter cuts.

Claim 24

The improvement of claim 20 including a quick connect and disconnect mounting for said pressure shoes on said guard drum.

Claim 25

The improvement of claim 21 wherein said quick connect and disconnect mounting includes screws on said drum and keyhole slots in said pressure shoes engageable by heads of said screws.

Claim 26

The improvement of claim 22 including a collar fixed on said shaft above said drum, a bearing between said drum and said shaft, and a compression spring around said shaft between said collar and said bearing for biasing said drum downward relative to said beam.

Claim 27

The improvement of claim 23 wherein said bearing includes a thrust bearing.