Motorized saw with movable blade guard actuating linkage

Claim 2

A cutting tool comprising: a base including a support member; a pivot shaft having a longitudinal axis and being supported by the support member; an arm mounted on the pivot shaft for pivotal movement about the axis; a cutting unit mounted on the arm for movement therewith between cutting and non-cutting positions, the cutting unit including a cutting blade mounted for rotation about an arbor axis, having a lower portion and having a blade guard supported for movement between a surrounding position wherein the blade guard surrounds the lower portion of the cutting blade and a non-surrounding position wherein the lower portion of the cutting blade is exposed for cutting; means for causing movement of the blade guard between the surrounding and non-surrounding positions in response to movement of the cutting unit between non-cutting and cutting positions, and the blade guard being freely manually pivotally movable from the surrounding position to the non-surrounding position whenever the cutting unit is in the non-cutting position to expose the saw blade for removal; and means for preventing movement of the cutting unit from the non-cutting position whenever the movable guard is rotated to the non-surrounding position to expose the saw blade for removal.

Claim 3

A cutting tool as set forth in claim 1 wherein the means for causing movement of the blade guard includes: a bell crank having a first end pivotally connected to the support arm for movement about a first axis, having a second end spaced from the first end and having a cam follower; and a link arm having opposite ends, one of the link arm ends being pivotally connected to the second end of the bell crank for movement about a second axis, and the other end of the link arm being pivotally connected to the blade guard for movement about a third axis.

Claim 4

A cutting tool as set forth in claim 2 wherein the means for causing movement of the blade guard includes a cam plate connected to the cutting unit, the cam plate having a cam surface adapted to engage the cam follower so that movement of the cutting unit from the non-cutting position to the cutting position causes movement of the blade guard from the surrounding position to the non-surrounding position, and wherein the means for preventing movement of the cutting unit from the non-cutting position until the movable guard is returned to the surrounding position includes a lost motion member on the cam plate, the lost motion member including a surface opposing and generally parallel to the cam surface, so that the lost motion member prevents manual movement of the lower blade guard whenever the cutting unit is out of the non-cutting position and so that the blade guard is freely manually movable to the non-surrounding position whenever the cutting unit is in the non-cutting position.

Claim 5

A cutting tool as set forth in claim 3 wherein the cam plate includes an end on the lost motion member, the end having a surface engaging the cam follower whenever the blade guard is manually pivoted to the non-surrounding position to prevent movement of the cutting unit from the non-cutting position to the cutting position whenever the blade guard has been manually pivoted to the non-surrounding position.

Claim 6

A cutting tool as set forth in claim 3 wherein the cam plate includes a keyway and wherein the cutting unit includes a housing having thereon a locating key contacting the keyway so that the cam plate is angularly adjustable about the locating key to an optimum operating position relative to the cam follower.

Claim 7

A cutting tool as set forth in claim 2 wherein the cutting unit has a first index, and wherein the blade guard has a second index, and wherein the cam plate is adjustable about the locating key relative to the cutting unit to cause movement of the blade guard so that when the second index of the lower blade guard is in alignment with the first index on the housing, the cam plate is in the optimum operating position.

Claim 8

A cutting unit as set forth in claim 2 wherein the bell crank has thereon a stop member contacting the link arm when the blade guard is moved to the non-surrounding position and the cutting unit is in the non-cutting position to prevent the third pivot axis from passing over a line extending between the second pivot axis and the arbor axis, and wherein the cutting unit includes a stop member contacting the blade guard whenever the blade guard is moved to the non-surrounding position and while the cutting unit is in the cutting position to prevent the third pivot axis from passing over a line extending between the second pivot axis and the arbor axis.

Claim 9

A cutting tool as set forth in claim 1 wherein the means for causing movement of the blade guard includes a leaf spring member connected between the support member and the bell crank to bias the movable blade guard to the surrounding position.

Claim 10

A cutting tool comprising: a base including a support member; a pivot shaft having a longitudinal axis and being supported by the support member; an arm mounted on the pivot shaft for pivotal movement about the axis; a cutting unit mounted on the arm for movement therewith between cutting and non-cutting positions, the cutting unit including an arbor mounted for rotation about an arbor axis, a cutting blade mounted on the arbor and having a lower portion and a blade guard supported for pivotal movement about the arbor axis between a surrounding position wherein the blade guard surrounds the lower portion of the cutting blade and a non-surrounding position wherein the lower portion of the cutting blade is exposed for cutting; a bell crank having a first end pivotally connected to the support arm for movement about a first axis, having a second end spaced from the first end and having a cam follower; a link arm having opposite ends, one of the link arm ends being pivotally connected to the second end of the bell crank for movement about a second axis and the other of the link arm ends being pivotally connected to the blade guard for movement about a third axis; and a cam plate connected to the cutting unit, the cam plate having a cam surface engaging the cam follower so that movement of the cutting unit from the non-cutting position to the cutting position causes movement of the blade guard from the surrounding position to the non-surrounding position, the cam plate also having a lost motion member including a surface opposing and generally parallel to the cam surface, so that the lost motion member prevents manual movement of the blade guard whenever the cutting unit is out of the non-cutting position and so that the blade guard is freely manually movable to the non-surrounding position whenever the cutting unit is in the non-cutting position, and the cam plate having means for preventing movement of the cutting unit from the non-cutting position to the cutting position when the blade guard has been manually pivoted to the non-surrounding position.

Claim 11

A cutting tool comprising: a base including a support member; a pivot shaft having a longitudinal axis and being supported by the support member; an arm mounted on the pivot shaft for pivotal movement about the axis; a cutting unit mounted on the arm for movement therewith between cutting and non-cutting positions, the cutting unit including an arbor mounted for rotation about an arbor axis, a cutting blade mounted on the arbor and having a lower portion and a blade guard supported for pivotal movement about the arbor axis between a surrounding position wherein the blade guard surrounds the lower portion of the cutting blade and a non-surrounding position wherein the lower portion of the cutting blade is exposed for cutting; a bell crank having a first end pivotally connected to the support arm for movement about a first axis, having a second end spaced from the first end and having a cam follower; a link arm having opposite ends, one of the link arm ends being pivotally connected to the second end of the bell crank for movement about a second axis and the other of the link arm ends being pivotally connected to the blade guard for movement about a third axis; and a cam plate connected to the cutting unit, the cam plate having a cam surface engaging the cam follower so that movement of the cutting unit from the non-cutting position to the cutting position causes movement of the blade guard from the surrounding position to the non-surrounding position, the cam plate also having a lost motion member including a surface opposing and generally parallel to the cam surface, so that the lost motion member prevents manual movement of the blade guard whenever the cutting unit is out of the non-cutting position and so that the blade guard is freely manually movable to the non-surrounding position whenever the cutting unit is in the non-cutting position, and the cam plate having means for preventing movement of the cutting unit from the non-cutting position to the cutting position when the blade guard has been manually pivoted to the non-surrounding position.

Claim 12

A cutting tool as set forth in claim 9 wherein the means on the cam plate for preventing movement of the cutting unit from the non-cutting position to the cutting position when the blade guard has been manually pivoted to the non-surrounding position comprises an end on the lost motion member, the end having a surface engaging the cam follower whenever the blade guard is manually pivoted to the non-surrounding position.

Claim 13

A cutting tool as set forth in claim 9 wherein the bell crank has thereon a stop member contacting the link arm when the blade guard is moved to the non-surrounding position and the cutting unit is in a non-cutting position to prevent the third pivot axis from passing over a line extending between the second pivot axis and the arbor axis.

Claim 14

A cutting tool as set forth in claim 9 wherein the cutting unit includes a stop member contacting the blade guard whenever the blade guard is moved to the non-surrounding position and the cutting unit is in a cutting position to prevent the third pivot axis from passing over a line extending between the second pivot axis and the arbor axis.

Claim 15

A cutting tool as set forth in claim 9 wherein the cam plate includes a keyway and wherein the cutting unit includes a housing having thereon a locating key contacting the keyway so that the cam plate is pivotally adjustable about the locating key to an optimum operating position relative to the cam follower.

Claim 16

A cutting tool as set forth in claim 9 wherein the cutting unit has a first index, and wherein the blade guard has a second index, and wherein the cam plate is pivotally adjustable relative to the cutting unit to cause movement of the cam follower, bell crank, link arm, and blade guard so that when the second index on the blade guard is in alignment with the first index on the housing, the cam plate is in the optimum operating position.

Claim 17

A cutting tool as set forth in claim 9, the cutting tool further including a leaf spring member connected between the support member and the bell crank to bias the blade guard to the surrounding position.

Claim 18

A cutting tool comprising: a base including a support member; a pivot shaft having a longitudinal axis and being supported by the support member; an arm mounted on the pivot shaft for pivotal movement about the axis; a cutting unit mounted on the arm for movement therewith between cutting and non-cutting positions, the cutting unit including a cutting blade having a lower portion, including a housing having a first index and including a cam plate having a cam surface and being pivotally connected to the cutting unit for pivotal adjustment relative to the cutting unit to an optimum operating position; a blade guard supported for pivotal movement between a surrounding position wherein the blade guard surrounds the lower portion of the blade and a non-surrounding position wherein the lower portion of the blade is exposed for cutting, and wherein the blade guard has a second index; and an actuating linkage connecting the support member to the blade guard to cause movement of the blade guard between the surrounding and the non-surrounding positions in response to movement of the cutting unit between the non-cutting and cutting positions, the actuating linkage including a cam follower connected to the support member and being positioned for movement along the cam surface, and wherein the cam follower is connected to the blade guard to cause movement of the blade guard between the surrounding and non-surrounding position in response to movement of the cam follower along the cam surface so that pivotal adjustment of the cam plate relative to the cutting unit causes movement of the actuating linkage and rotation of the blade guard and so that the second index of the blade guard is alignable with the first index on the housing to indicate that the cam plate is in the optimum operating position.

Claim 19

A cutting tool comprising: a base including a support member; a pivot shaft having a longitudinal axis and being supported by the support member; an arm mounted on the pivot shaft for pivotal movement about the axis; a cutting unit mounted on the arm for movement therewith between cutting and non-cutting positions, the cutting unit including a cutting blade having a lower portion, including a housing having a first index and including a cam plate having a cam surface and being pivotally connected to the cutting unit for pivotal adjustment relative to the cutting unit to an optimum operating position; a blade guard supported for pivotal movement between a surrounding position wherein the blade guard surrounds the lower portion of the blade and a non-surrounding position wherein the lower portion of the blade is exposed for cutting, and wherein the blade guard has a second index; and an actuating linkage connecting the support member to the blade guard to cause movement of the blade guard between the surrounding and the non-surrounding positions in response to movement of the cutting unit between the non-cutting and cutting positions, the actuating linkage including a cam follower connected to the support member and being positioned for movement along the cam surface, and wherein the cam follower is connected to the blade guard to cause movement of the blade guard between the surrounding and non-surrounding position in response to movement of the cam follower along the cam surface so that pivotal adjustment of the cam plate relative to the cutting unit causes movement of the actuating linkage and rotation of the blade guard and so that the second index of the blade guard is alignable with the first index on the housing to indicate that the cam plate is in the optimum operating position.

Claim 20

A cutting tool as set forth in claim 16 wherein the actuating linkage includes a bell crank supporting the cam follower, the bell crank including one end connected to the support member and an opposite end spaced from the one end, the actuating linkage further including a link member having one end connected to the opposite end of the bell crank and having a second end connected to the blade guard, and wherein the blade guard is freely movable to the non-surrounding position whenever the cutting unit is in the non-cutting position.

Claim 21

A cutting tool as set forth in claim 16 wherein the cutting unit includes an arbor mounted for rotation about an arbor axis, wherein the cutting blade is mounted on the arbor for rotation therewith, wherein the actuating linkage includes a bell crank mounted for pivotal movement relative to the cutting unit about a first axis, the one end of the link member pivots relative to the bell crank about a second axis, and the second end of the link member pivots relative to the bell crank about a third axis, and wherein the bell crank includes a stop member adapted to contact the link member whenever the blade guard is moved to the non-surrounding position while the cutting unit is in a non-cutting position, the stop member preventing the third pivot axis from passing over a line extending between the second pivot axis and the arbor axis.

Claim 22

A cutting tool as set forth in claim 18 wherein the cutting unit includes a second stop member adapted to contact the blade guard when the blade guard is moved to the non-surrounding position while the cutting unit is in a cutting position, the second stop member preventing the third pivot axis from passing over the line extending between the second pivot axis and the arbor axis.

Claim 23

A cutting tool as set forth in claim 18 wherein the first index comprises an index line formed in the housing of the cutting unit and wherein the second index comprises an edge on the blade guard, the cutting tool further comprising means for securing the cam plate in the optimum operating position.