A hole saw including a plurality of sidewall openings is provided. The sidewall openings are shaped and grouped in patterns that improve debris ejection of the hole saw and that allow for easy access to the interior of the hole saw for manual debris removal by the user. The opening groups are space from each other by larger uninterrupted areas such that the hole saw has a high strength despite the number and size of openings provided in the saw sidewall.

A hole saw including a plurality of sidewall openings is provided. The sidewall openings are shaped and grouped in patterns that improve debris ejection of the hole saw and that allow for easy access to the interior of the hole saw for manual debris removal by the user. The opening groups are space from each other by larger uninterrupted areas such that the hole saw has a high strength despite the number and size of openings provided in the saw sidewall.

A tool holder having a main body for coupling the tool holder to the spindle of a machine tool and having a clamping surface connected thereto for clamping a tool, characterized in that the tool holder has at least one portion shaped in one piece by primary shaping, which in its interior has one or more cavities that form an enclave in the portion shaped by primary shaping.

A bit adapter is provided, which includes a bit-installing portion, a middle portion, and a shank portion. The bit-installing portion has a hexagonal socket hole for receiving a drill tip of a first size. The middle portion is extended from a rear portion of the front chuck portion for a specific length. The shank portion is extended from a rear portion of the middle portion and having a hexagonal cross-section of a second size. The shank portion is configured to be received by a drill. A bit adapter set with four different sizes of bit adapters enables a user to have a flexibility to choose drills and drill bits. A three-piece bit adapter increases the flexibility still further.

An integrated drill chuck for installing mine roof bolts includes a single integrated piece, the single integrated piece including a body defining a receiving cavity, where the receiving cavity is configured to receive and secure a bit having a square-shaped end and a bit having a hex-shaped end. A drill for installing mine roof bolts is also disclosed. A method for installing mine roof bolts is also disclosed.

A coupling arrangement for a tool, the coupling arrangement comprising a drive part rotatable about a rotation axis, the drive part comprising a drive profile; a driven part rotatable about the rotation axis, the driven part comprising a driven profile complementary to the drive profile, the driven profile being arranged to mate with the drive profile in a coupled position for torque transfer between the drive part and the driven part; and an aligning arrangement arranged to force a relative rotation between the drive part and the driven part about the rotation axis from a nonaligned state of the coupling arrangement, where the drive profile is not rotationally aligned with the driven profile, towards an aligned state of the coupling arrangement, where the drive profile is rotationally aligned with the driven profile.

A system is disclosed for releasable coupling of a hole saw to a drill arbor. The system includes an elongate drill arbor configured at a first end to be clamped in a drill chuck of a drill, and a hole saw adapter provided with a longitudinal bore in which the drill arbor can be received so that an inner surface of the longitudinal bore of the hole saw adapter is mounted slidably on an outer surface of the drill arbor in the longitudinal direction of the drill arbor. The drill arbor includes an actuator member and at least one retaining element co-acting therewith. The inner surface of the longitudinal bore of the hole saw adapter is provided with a recess into which the retaining element of the drill arbor can protrude.

A tool holder having a tool receptacle for chucking a tool shaft by frictional engagement, in which the tool receptacle comprises a plurality of annular clamping surfaces spaced apart from one another, which are intended for retaining the tool shaft by nonpositive engagement and are embodied on the inner circumference of a tube part, and the tube part has a recess in the material for varying its clamping action; the recess in the material is embodied by a plurality of annular channels extending in the circumferential direction, which are each separated from the tool receptacle by a resilient wall portion, which on its side facing away from the channel embodies the respective clamping surface.

A hole saw including a plurality of sidewall openings is provided. The sidewall openings are shaped and grouped in patterns that improve debris ejection of the hole saw and that allow for easy access to the interior of the hole saw for manual debris removal by the user. The opening groups are space from each other by larger uninterrupted areas such that the hole saw has a high strength despite the number and size of openings provided in the saw sidewall.

A hole saw including a plurality of sidewall openings is provided. The sidewall openings are shaped and grouped in patterns that improve debris ejection of the hole saw and that allow for easy access to the interior of the hole saw for manual debris removal by the user. The opening groups are spaced from each other by larger uninterrupted areas such that the hole saw has a high strength despite the number and size of openings provided in the saw sidewall.