A method of detecting kickback during operation of a saw includes identifying with a controller in a saw a measured rotational speed of a rotating blade in the saw with reference to signals from a rotational rate sensor, identifying with the controller an estimated rotational speed of the rotating blade in the saw with reference to the measured rotational speed, at least one previously measured rotational speed, and a measurement of a previous change in rotational speed of the rotating blade, identifying with the controller an estimated torque force for a drive shaft of a motor in the saw that rotates the blade with reference to the measured rotational speed, and activating with the controller a blade arrest mechanism in response to a difference between the measured rotational speed and the estimated rotational speed exceeding a first threshold and the estimated torque force exceeding a second threshold.

A method of detecting kickback during operation of a saw includes identifying with a controller in a saw a measured rotational speed of a rotating blade in the saw with reference to signals from a rotational rate sensor, identifying with the controller an estimated rotational speed of the rotating blade in the saw with reference to the measured rotational speed, at least one previously measured rotational speed, and a measurement of a previous change in rotational speed of the rotating blade, identifying with the controller an estimated torque force for a drive shaft of a motor in the saw that rotates the blade with reference to the measured rotational speed, and activating with the controller a blade arrest mechanism in response to a difference between the measured rotational speed and the estimated rotational speed exceeding a first threshold and the estimated torque force exceeding a second threshold.

Power saws and features for power saws are disclosed. Various features are particularly relevant to jobsite or benchtop table saws, such as a trunnion formed from a shaped tube, an elevation carriage, and an arbor block retention mechanism. Other features are particularly relevant to table saws, hand-held circular saws, track saws, miter saws, and band saws with active injury mitigation technology, such as an electrically isolating gear and an overmolded arbor/gear element.

Fast-acting and low-inertia actuators useable in various applications where a high force must be applied very quickly are disclosed. Power tools with detection systems configured to detect a dangerous condition between a person and a cutting tool are disclosed. In power tools, for example in a woodworking machine, a fast-acting and low-inertial actuator as disclosed herein can be used to retract a blade upon detection of a dangerous condition by a detection system. The actuator includes a charge of pressurized fluid and one or more electromagnets to selectively retain or release the pressurized fluid.

The present invention concerns a method and an arrangement for processing calcinated carbon bodies such as anodes or cathodes for use in connection with electrolytic production of aluminium. The carbon bodies are processed using a rotating processing tool (101) that consists of a mainly circular disc with cutting edges (114) mounted at its periphery. The cutting edges may be made of polycrystalline diamond (PCD) or an equivalent material. The rotating processing tool mounted on a rotating, driven spindle and is guided by guiding elements (110) that can be jets or perforated discs that blows pressurized air at the tool, or rollers (120). With the present invention it is possible to create narrow and deep slots in calcinated carbon bodies in an efficient manner with low tool wear.

Machines with safety systems are disclosed. The machine may take the form of woodworking machines including table saws, band saws, miter saws, hand-held circular saws, pneumatic chop saws, radial-arm saws, jointers, planars, routers and shapers. The machines may include an operative structure configured to perform a task, where the operative structure includes a cutting tool adapted to move in at least one motion, and a safety system adapted to detect the occurrence of an unsafe condition between a person and the cutting tool and for mitigating the unsafe condition. The safety system may include a detection subsystem and a reaction subsystem. The machine may also include a bypass or override mode where in an injury mitigation system is disabled for certain cuts.

Machines with safety systems are disclosed. The machine may take the form of woodworking machines including table saws, band saws, miter saws, hand-held circular saws, pneumatic chop saws, radial-arm saws, jointers, planars, routers and shapers. The machines may include an operative structure configured to perform a task, where the operative structure includes a cutting tool adapted to move in at least one motion, and a safety system adapted to detect the occurrence of an unsafe condition between a person and the cutting tool and for mitigating the unsafe condition. The safety system may include a detection subsystem and a reaction subsystem. The machine may also include a bypass or override mode where in an injury mitigation system is disabled for certain cuts.

Table saws with safety systems are disclosed. The safety systems detect and react to dangerous conditions, such as contact between the blade and a person. The table saws may include a switch, a first light that illuminates to indicate the safety system is operable, and a second light that illuminates to indicate that the safety system is inoperable. The switch may not power the saw when switched on if the second light is illuminated.

The invention relates to a tool apparatus (10) with a drivable tool (1), comprising a shaft (2) which is coupled to the tool (1), further comprising one or plural braking bodies (3) which in particular are arranged distributed around the shaft (2) in the circumferential direction, wherein the tool apparatus (10) is adapted to bring the one or plural braking bodies (3) from a release state into a braking state in the course of a braking procedure, wherein in the braking state the one or the plural braking bodies (3) are in contact with the shaft and thereby exert a braking force upon the shaft (2), so that the shaft (2) and thereby also the tool (1) are braked and wherein in the release state the one or the plural braking bodies (3) are not in contact with the shaft (2).

Woodworking machines and safety methods for use with those machines are disclosed. The machines include a detection system adapted to detect one or more dangerous conditions and a reaction system associated with the detection system. The reaction system can include an explosive to trigger the system, and also can be configured to retract a cutting tool at least partially away from a cutting region upon detection of a dangerous condition by the detection system.