A hand-held belt sander includes a head, an arm, a retaining unit, and a positioning unit. The head includes a mounting seat surrounding an axis. The arm has a sleeve segment mounted to the mounting seat. The retaining unit has an annular groove formed in the mounting seat, and multiple protrusions disposed on the sleeve segment and engaging the annular groove. The positioning unit includes multiple engaging grooves formed in the mounting seat, and an engaging member disposed on the sleeve segment. When the engaging member engages one of the engaging grooves, the arm is positioned relative to the head at an operating position. When the engaging member is disengaged from the one of the engaging grooves, the arm is rotatable about the axis relative to the head.

A power tool which contains a casing, a brushless motor (22) mounted inside the casing, a user actuated switch (38) mounted on the casing, and a circuit board (32) mounted inside the casing. The brushless motor (22) is adapted to drive one or more movable parts in the power tool. The circuit board (32) is mechanically connected to the brushless motor (22) and the switch (38) at the same time. As only a single, integrated circuit board (32) is configured in the power tool, the manufacturing cost is reduced and greater reliance and electrical safety can be achieved.

A power tool which contains a casing, a brushless motor (22) mounted inside the casing, a user actuated switch (38) mounted on the casing, and a circuit board (32) mounted inside the casing. The brushless motor (22) is adapted to drive one or more movable parts in the power tool. The circuit board (32) is mechanically connected to the brushless motor (22) and the switch (38) at the same time. As only a single, integrated circuit board (32) is configured in the power tool, the manufacturing cost is reduced and greater reliance and electrical safety can be achieved.

An expandable handheld pneumatic belt grinder includes a body, an expansion component and an operation component. The body has a receiving space, a pneumatic motor, and a rotating wheel driven by the pneumatic motor. The expansion component has an expansion pipe and an expansion rod which are connected. The expansion rod is coupled to the receiving space. The operation component has a support rod with one end carrying a driven wheel and the other end coupled to the receiving space or expansion pipe. A grinding belt fits around the driven wheel and rotating wheel collectively. A user changes the distance between the rotating wheel and driven wheel by choosing between two options: coupling the support rod of operation component and the receiving space; and coupling the expansion rod of expansion component and the receiving space, and then coupling the support rod of operation component and the expansion pipe.

An expandable handheld pneumatic belt grinder includes a body, an expansion component and an operation component. The body has a receiving space, a pneumatic motor, and a rotating wheel driven by the pneumatic motor. The expansion component has an expansion pipe and an expansion rod which are connected. The expansion rod is coupled to the receiving space. The operation component has a support rod with one end carrying a driven wheel and the other end coupled to the receiving space or expansion pipe. A grinding belt fits around the driven wheel and rotating wheel collectively. A user changes the distance between the rotating wheel and driven wheel by choosing between two options: coupling the support rod of operation component and the receiving space; and coupling the expansion rod of expansion component and the receiving space, and then coupling the support rod of operation component and the expansion pipe.

A system for polishing an outer surface of a specimen, the system including a motor and a rotatable shaft extending from a first end of the motor, wherein the specimen is removably attachable to the rotatable shaft, a safety cover configured to at least partially surround at least a portion of the rotatable shaft, wherein the safety cover includes a top panel, a first side panel and a second side panel spaced from each other across a width of the safety cover and extending downwardly from the top panel, and at least one aperture extending through at least one of the first and second side panels. The system further includes an abrasive material insertable through the at least one aperture so that the abrasive material is positionable to contact the outer surface of the specimen.

A system for polishing an outer surface of a specimen, the system including a motor and a rotatable shaft extending from a first end of the motor, wherein the specimen is removably attachable to the rotatable shaft, a safety cover configured to at least partially surround at least a portion of the rotatable shaft, wherein the safety cover includes a top panel, a first side panel and a second side panel spaced from each other across a width of the safety cover and extending downwardly from the top panel, and at least one aperture extending through at least one of the first and second side panels. The system further includes an abrasive material insertable through the at least one aperture so that the abrasive material is positionable to contact the outer surface of the specimen.

A belt sander includes a main casing, a frame arm rotatably connected to the main casing, an abrasive belt mounted to the frame arm and adapted to be driven by electric power, a positioning member, a first sensor and a second sensor. The positioning member is movably mounted to the main casing and is movable relative to the main casing between a releasing position, where the first and second sensors are in a first sensor state, and where the second sensor generates a first signal for ceasing the electric power, and a first engaging position, where the first and second sensors are in the second sensor state, and where the second sensor generates a second signal for conducting the electric power.

A belt sander includes a main casing, a frame arm rotatably connected to the main casing, an abrasive belt mounted to the frame arm and adapted to be driven by electric power, a positioning member, a first sensor and a second sensor. The positioning member is movably mounted to the main casing and is movable relative to the main casing between a releasing position, where the first and second sensors are in a first sensor state, and where the second sensor generates a first signal for ceasing the electric power, and a first engaging position, where the first and second sensors are in the second sensor state, and where the second sensor generates a second signal for conducting the electric power.

A belt sander includes a frame, a drive roller, an idler roller rotatably attached to a pivot arm, a first linear actuator configured for pivoting the pivot arm, a nose roller and a continuous abrasive belt wrapped around the drive roller, the idler roller and the nose roller. A drive motor rotates the drive roller, and an air cylinder attached to the frame and a nose roller spindle exerts a first force against the frame and a second force equal to and opposite the first force against the nose roller spindle. A first sensor senses a position of a belt edge, and a first controller receives a belt edge position signal from the first sensor and sends a command signal responsive to the position signal to the first linear actuator for expanding or contracting so as to pivot the pivot arm about a pivot point.