A center locator is operated with a hole center for enlarging a round opening and includes a center seat having a through hole centrally defined therein, wherein the through hole is adapted to allow a centering drill of the hole cutter extending through the center seat. At least one adjusting device is longitudinally mounted to the center seat and formed with an engaging portion, wherein the at least one adjusting device is expandable relative to the center seat for adjusting a distance between the engaging portion of the at least one adjusting device and a center of the center seat.

A cutting tool includes a hole saw, a pilot bit, and an arbor assembly. The arbor assembly includes a shank, a sleeve, a first ball bearing moveable relative to the shank, the first ball bearing engaging the hole saw to releasably secure the hole saw to the shank, and a second ball bearing moveable relative to the shank, the second ball bearing engaging the pilot bit to releasably secure the pilot bit to the shank. The sleeve is moveable to a first position where the hole saw and the pilot bit are secured to the arbor assembly, to a second position where the first ball bearing disengages the hole saw, allowing removal of the hole saw from the shank, and to a third position where the second ball bearing disengages the pilot bit, allowing removal of the pilot bit from the shank.

This invention relates to a saw blade quick release mechanism for sawing tool and a sawing tool using same, the mechanism comprising a saw blade mount, a rotary cover rotatable on the saw blade mount, a resilient member holding the rotary cover in position, and a positioning component having a positioning member on either of the saw blade mount and the rotary cover and a positioning slot on the other one thereof whereby in case of the rotary cover positioned, the positioning member is at the positioning end of the positioning slot, and the saw blade cannot be disassembled then, while in case of the rotary cover disassembled, the positioning member is at a release end thereof, and the saw blade can be disassembled then.

A rotary cutting unit for a rotary saw has a cross bar and at least one cutting structure, wherein the cutting structure is in contact with the cross bar. The cross bar runs through sleeve holes. The center of gravity of the turning unit is located in an axis of the center of the sleeve holes. The axis is perpendicular to the transverse axis of the crossbar. The rotary saw selectively installs the rotary cutting unit of the corresponding specification, and it can quickly and easily change the aperture of the circular hole to be processed, and with high usability.

A rotary cutting unit for a rotary saw has a cross bar and at least one cutting structure, wherein the cutting structure is in contact with the cross bar. The cross bar runs through sleeve holes. The center of gravity of the turning unit is located in an axis of the center of the sleeve holes. The axis is perpendicular to the transverse axis of the crossbar. The rotary saw selectively installs the rotary cutting unit of the corresponding specification, and it can quickly and easily change the aperture of the circular hole to be processed, and with high usability.

A rotary cutting unit for a rotary saw has a cross bar and at least one cutting structure, wherein the cutting structure is in contact with the cross bar. The cross bar runs through sleeve holes. The center of gravity of the turning unit is located in an axis of the center of the sleeve holes. The axis is perpendicular to the transverse axis of the crossbar. The rotary saw selectively installs the rotary cutting unit of the corresponding specification, and it can quickly and easily change the aperture of the circular hole to be processed, and with high usability.

Holder for a rotary tool which holder is formed with a holder body comprising a rear drive end and a front connection end having a connection thread for the connection of the tool. The holder comprises a thrust collar having a flat contact surface facing a connection end of the holder. The holder comprises an axially movable operating means, a number of restraint elements placed in one or more spaces in the holder body which restraint elements in a first axial position of the operating means are prevented from radial movement in said spaces and which restraint elements in a second axial position of the operating means allow radial movement in said spaces. Each one of said spaces for the restraint elements is limited in the axial direction by a front limiting wall and a rear limiting wall, which two limiting walls are parts of the holder body.

A hole cutter assembly is operable to cut a plurality of different sized diameter holes in a work piece. The hole cutter assembly includes an arbor configured to connect to a power tool for rotation about an axis, a drill bit coupled to the arbor for rotation with the arbor, a first arm moveable relative to the axis, a first cutting blade coupled to the first arm and moveable with the first arm, a second arm moveable relative to the axis, and a second cutting blade coupled to the second arm and moveable with the second arm. The first and second cutting blades are selectively moveable relative to the axis to adjust a cutting diameter of the hole cutter assembly. The drill bit engages the first and second arms to inhibit movement of the first and second cutting blades relative to the drill bit.

A hole cutter assembly is operable to cut a plurality of different sized diameter holes in a work piece. The hole cutter assembly includes an arbor configured to connect to a power tool for rotation about an axis, a drill bit coupled to the arbor for rotation with the arbor, a first arm moveable relative to the axis, a first cutting blade coupled to the first arm and moveable with the first arm, a second arm moveable relative to the axis, and a second cutting blade coupled to the second arm and moveable with the second arm. The first and second cutting blades are selectively moveable relative to the axis to adjust a cutting diameter of the hole cutter assembly. The drill bit engages the first and second arms to inhibit movement of the first and second cutting blades relative to the drill bit.

A mandrel assembly includes a mandrel, adapter, and bit coupler. The mandrel includes a shank part axially disposed in the mandrel, an adapter receiver, and a coupler receiver. An internal hole runs axially through the adapter. The coupler includes first and second axial sections, and an axial bit connection hole with a polygonal section proximate to an inner side, and a cylindrical section proximate to an opening. An outer wall of the adapter fits with an inner wall of the adapter receiver. An outer wall of the first section fits with an inner wall of the coupler receiver. An outer wall of the second coupler fits with the internal hole of the adapter. The mandrel transmits torque, via the adapter receiver and coupler receiver, to the adapter and then to a hole saw coupled to the adapter, and to the coupler and then to a bit coupled to the coupler.